FBI leaders have warned that they believe hackers who broke into AT&T Inc.’s system last year stole months of their agents’ call and text logs, setting off a race within the bureau to protect the identities of confidential informants, a document reviewed by Bloomberg News shows.
FBI officials told agents across the country that details about their use on the telecom carrier’s network were believed to be among the billions of records stolen, according to the document and interviews with a current and a former law enforcement official. They asked not to be named to discuss sensitive information. Data from all FBI devices under the bureau’s AT&T service for public safety agencies were presumed taken, the document shows.
The cache of hacked AT&T records didn’t reveal the substance of communications but, according to the document, could link investigators to their secret sources. The data was believed to include agents’ mobile phone numbers and the numbers with which they called and texted, the document shows. Records for calls and texts that weren’t on the AT&T network, such as through encrypted messaging apps, weren’t part of the stolen data.
AT&T publicly disclosed the breach in July and said it included six months worth of mobile phone customer data from 2022. The hackers threatened to sell the data unless the telecommunications company paid an extortion fee.
A person with knowledge of the breach, who reviewed a sample of the stolen information, confirmed that it contained records of sensitive FBI communications: the call logs of at least one agent. The person asked not to be named because the information is private.
The FBI’s concern about the hack compromising its secret sources, which hasn’t been previously reported, highlights how data stolen from phone companies has the potential to disrupt criminal investigations and national security. Former agents said it also raises questions about the bureau’s own security practices and how it safeguards its sources. US authorities are still investigating a separate breach of nine telecommunications companies, including AT&T. They blamed Chinese state-backed hackers for those intrusions, which compromised the communications of a number of people in government and politics.
The FBI declined to answer specific questions, including whether the April breach of AT&T compromised sources or investigations, or if the stolen data has since been secured. “The FBI continually adapts our operational and security practices as physical and digital threats evolve,” the agency said in a statement. “The FBI has a solemn responsibility to protect the identity and safety of confidential human sources, who provide information every day that keeps the American people safe, often at risk to themselves.”
AT&T spokesperson Alex Byers said, “After criminals stole customer data last year, we worked closely with law enforcement to mitigate impact to government operations.” He said the company appreciates law enforcement’s recent arrests for the breach and continues to “increase investments in security as well as monitor and remediate our networks.”
Former FBI and intelligence officials said stolen phone records could in theory be used by a foreign espionage service to unravel painstakingly assembled source networks, potentially imperiling criminal probes, national security operations and people’s lives.
“Any disclosure of such communications is both significantly detrimental to investigations but also potentially dangerous to confidential informants if their identity is disclosed,” said William Evanina, a retired FBI agent and the former director of the National Counterintelligence and Security Center. “Not good.”
Concerns about Israel’s newfound hostility toward Syria’s new Islamist government, run by al-Qaeda-linked Hayat Tahrir al-Sham (HTS) grew substantially on Wednesday after an Israeli drone attacked a military convoy belonging to the new government in the southern Quneitra Governorate. Three people were killed, two fighters and a civilian.
Despite hundreds of Israeli airstrikes on remnants of the Assad government across Syria in the past month, this is significant because it is the first time Israel has attacked active personnel with the new, post-Assad government.
Israel was supposed to be happy with the regime change, and Prime Minister Netanyahu even took credit for Assad’s ouster last month. This did come with Israel’s invasion and occupation of significant territory in southern Syria though, including parts of the Quneitra and Daraa Governorates.
In recent days, Israel has been more openly hostile toward the HTS, and used this as an excuse for extending their occupation of those parts of Syria indefinitely. The HTS has talked about trying to be on friendly terms with Israel, but this doesn’t seem to be in the cards at the end of the day.
Israel has taken the demilitarized zone previously held by the UN Syria Disengagement Observer Force (UNDOF), along with some towns and villages across the zone in Syria itself.
In al-Harra, a village in Quneitra Israeli troops haveordered over 1,000 civilians to leave. They arrived one day, told the imam to use the Muezzin microphone to announce the order for everyone to leave by 3 p.m. the same day.
The civilians left, especially the women and children. A lot of the men stayed and some people are trying to return. There was no real provision made for displaced people, and most of those who fled were given little to no time to gather belongings, so they feel they have little choice but to return, even if it risks attacks by Israeli forces. Right now, it is estimated that around half of the population of al-Harrahas been displaced.
Though Israel initially presented this as an immediate need for border security along the border between Syria and the part of Syria Israel had already occupied since 1967. In recent days though the talk of a long-term presence has many fearing it's just another permanent Israeli occupation.
Though the US State Department has endorsed the Israeli invasion and occupation of Syria, it has led to disquiet in the international community. Turkey is particular, a strong backer of the HTS, has criticized the Israeli aggression, and demanded that they withdraw from Syria, warning "unfavorable outcomes" if they stay.
Israel’s Foreign Ministry angrily rejected the Turkish position, insisting Turkey is the real "imperialist actor." Turkey has been intervening against the Kurdish SDF in northern Syria for weeks, and President Erdogan’s call for Israeli withdrawal was couched as the international community taking “hands off Syria” to allow Turkey to wipe out ISIS and the SDF.
When Gury Doshi, MD, learned that a patient’s insurance didn’t cover her breast cancer medication, Doshi had a potential workaround. The patient could try to bypass the insurer and access the drug at little or no cost through a patient assistance program hosted by the drug manufacturer.
Almost all major pharmaceutical companies offer this type of financial assistance to patients who meet certain eligibility criteria, which has generally included those who are uninsured or underinsured and likely wouldn’t be able to afford such expensive prescriptions.
Estimates suggested that companies spend about $4 billion a year to keep these financial assistance programs running, and the programs include steep discounts for more than 300 drugs overall.
As Doshi soon discovered, the list included the breast cancer drug her patient needed.
The 59-year-old patient was approved for the drugmaker’s patient assistance program and soon began receiving the oral breast cancer agent at no cost, said Doshi, a medical oncologist and hematologist at Texas Oncology in Houston.
However, the drugmaker recently announced that patients with commercial health insurance would no longer be eligible for its patient assistance program starting in 2025.
“Now, we don’t know what’s going to happen for her,” Doshi explained. “It’s very disconcerting to say, ‘We were able to work things out to get you started on medication, but we don’t know what’s going to happen next year.’”
“It’s very traumatizing for patients,” Doshi said.
Oncologists and patients across the country are increasingly encountering this problem, as more drug manufacturers are banning or restricting commercially insured patients from their patient assistance programs. Since 2023, several major drug manufacturers — AstraZeneca, Bristol-Myers Squibb, Johnson & Johnson, Pfizer, and most recently Novartis — made this move, leaving thousands of previously eligible patients without this financial support. After facing pushback, however, AstraZeneca changed course in late 2024 and began allowing certain eligible commercially-insured patients to enter its AZ&Me program again. According to the company, these may include patients who have been denied coverage by their plan, who have exhausted their copay benefit, or who don’t have a prescription plan as part of their benefit.
Outside of patient assistance programs, which often provide the most comprehensive help, patients have several other pharmacy assistance options, such as copay assistance or foundation-based grants. And about one third of patients prescribed oral anticancer drugs rely on either pharmaceutical company– or foundation-sponsored financial assistance programs.
“Many of our patients are only able to access these life-saving or life-prolonging therapies through assistance programs as their copays would otherwise be prohibitive,” Meera Ragavan, MD, MPH, a medical oncologist at Kaiser Permanente San Francisco Medical Center, San Francisco, told Medscape Medical News.
But with drug companies tightening access to this essential financial lifeline, patients and oncologists are left scrambling to find other ways to get these treatments.
Inside Insurer Cost-Shifting
What’s fueling patients’ growing reliance on pharmacy assistance programs?
There are several key factors at play here.
First, cancer drugs are getting more expensive. The average annual cost of new cancer drugs in the United States rose by 53% between 2017 and 2021, from $185,000 to more than $283,000 a year, according to The Lancet Oncology.
Second, insurance companies are increasingly restricting the cancer drugs they will cover and finding ways to defer the costs of these expensive agents to others. About 1 in 4 patients say their commercial health plan deems their specialty medication to be a “nonessential health benefit,” according to a 2023 poll from the PAN Foundation, a healthcare advocacy organization. The poll found that about 1 in 3 respondents said their plan directed them to find financial assistance for their specialty medication. The same percentage were told that any financial aid they received for their specialty medication would not count toward their deductible or out-of-pocket maximum.
In fact, the existence of patient assistance programs may provide “little incentive for payors to provide robust coverage of specialty drugs or for manufacturers to lower drug prices,” Ragavan and colleagues wrote in their review.
In recent years, insurers have been ramping up cost-shifting strategies to reduce their own spending on expensive drugs. These strategies include copay accumulator and maximizer programs as well as alternative funding programs, all run by third parties.
With copay accumulator programs, patients receive a copay card from the manufacturer with a fixed amount to help them pay for the drug. The caveat to a copay card is the funds do not count towards a patient’s out-of-pocket maximums and, depending on the amount and the cost of the drug, the funds can be depleted quickly.
Copay maximizer programs are features of an insurance plan that maximize the amount of manufacturer copay assistance a patient receives. When patients enroll in these programs, a third party determines the maximum amount of copay assistance available from the manufacturer and the insurance plan sets the patient’s copay to that amount. However, these programs also bar the manufacturer’s payments from counting toward a patient’s deductible and out-of-pocket maximum.
“When you buy insurance, you figure you’ve got a deductible and you’ve got some copays, but eventually you’ll get to the place where the insurance company picks up the whole burden,” said Barbara L. McAneny, MD, a medical oncologist/hematologist who practices in the Albuquerque, New Mexico area. “That’s how insurance works. But with copay accumulators and maximizers, [insurers] play games in such a way that the patients can never get to their complete out-of-pocket max.”
The third-party vendors that run alternative funding programs claim to help employers reduce their healthcare costs by assuming a health plan’s responsibility for covering specialty drugs. Under these programs, insurance plans define specialty medications as nonessential and notify patients they must enroll in an alternative funding program to get the medication they need. Alternative funding programs, however, generally exclude or deny specialty drugs and then help patients access the medications through drugmaker patient assistance programs. In most cases, patients are required to work with alternative funding programs or are left paying the full cost of their medications.
Copay accumulator and maximizer programs as well as alternative funding programs are now common among commercial insurance plans, according to a 2024 analysis. In 2022, an estimated 39% of commercially insured patients were enrolled in plans with copay accumulators, 41% had plans with copay maximizers, and 12% were enrolled in plans with alternative funding programs, according to the study.
With oral anticancer agents getting more expensive, patients may be relying more heavily on financial assistance programs, and this growing reliance may be driving drug companies to limit patients’ eligibility.
According to a spokesperson for Pharmaceutical Research and Manufacturers of America, a trade association for pharmaceutical manufacturers, the wave of pharmacy assistance program restrictions is a reaction to the increasing coverage restrictions from insurers.
When asked directly by Medscape Medical News, however, drug companies did not address this specific claim.
In 2024, Pfizer announced that it would no longer accept new commercially insured oncology patients into its patient assistance program. A spokesperson for Pfizer said its patient assistance program is “designed to serve patients with the greatest financial need,” and as more options become available to help patients afford their medicines, Pfizer reviews and updates the eligibility criteria of its patient assistance program to ensure the company can continue to provide a wide range of medicine free of cost to eligible patients, the spokeswoman said.
“We understand that these changes may affect some of our patients and are working to ensure a smooth transition,” the spokeswoman said.
A spokesperson for AstraZeneca noted that its AZ&Me patient assistance program was never designed for patients with commercial insurance. Although that option was removed after July 2023 “to protect the integrity of the program,” the company backtracked late last year and began allowing commercially insured patients once again.
“In reality, the drug companies are figuring out real quick, ‘I’m not playing this game anymore. You’re making these patients pay all these premiums, but you’re not actually wanting to help the patient and pay for their drugs.’” said Lindsey Scott, manager of pharmacy services for Texas Oncology. “The drugmakers are sick of it, so they’re refusing to accept commercially-insured patients into their patient assistance programs.”
But, Scott said, this tug of war between health insurers and drug companies ultimately “leaves the patient right smack in the middle.”
Restrictions Put Patients in Jeopardy
For patients who have been taking cancer medications for years, the new restrictions to patient assistance programs are disrupting regimens and putting progress at risk, said Brooke Looney, PharmD, a clinical pharmacist with the outpatient oncology specialty pharmacy at Vanderbilt University Medical Center in Nashville, Tennessee.
Looney recalled a grocery store employee in his 40s whose oral cancer treatments had kept his metastatic melanoma under control for 4 years. The total price for his two medications is $45,000 a month. The patient’s commercial insurance includes a pharmacy benefit plan that covers up to 45% of specialty medications.
In past years, the patient used a copay card, which allotted $25,000 a year toward his out-of-pocket costs, said Looney, who provides access support to patients on oral anticancer medications at Vanderbilt. After the card was maxed out, the patient qualified for the drugmaker’s patient assistance program, which paid the remaining cost.
But in 2024, the patient was excluded from the financial assistance program because commercial insurance was no longer allowed, Looney said. That means, after about 1 month of copay help, the patient would be left paying about $25,000 a month.
For months, Looney and her team exhausted all efforts trying to help the patient pay for his medication, appealing to his human resources department, the pharmacy plan, and the drugmaker.
But nothing worked.
“The patient worried how he would continue the medication that had worked for 4 years to keep him stable and stop his disease from progressing,” Looney said. “I was thinking, ‘We’ve got to keep fighting because there’s no way we can let this patient go off therapy.’”
Looney’s team supplemented the patient with samples of the medications while they continued to write letters, make calls, and search for financial assistance, she said.
Finally, the team secured more funding for him through an internal assistance program run by the pharmacy that contracts with his insurer. The program agreed to cover the remaining medication costs.
“That’s our Band-Aid” for now, Looney said. But “it makes me nervous.”
“If that pharmacy ever deems him ineligible, or they change their parameters, it’s going to come back to us again to try to figure out how to get him the medication,” Looney said.
Cancer care center staff often work tirelessly to help patients access their medication, but much of the burden can fall on patients, Doshi added. Some plans or human resources departments will only discuss financial matters with patients, and patients are frequently forced to endure endless back-and-forth, she said.
Patients left with paying high out-of-pocket costs for cancer medications are at greater risk for forging their treatment.
A study in the Journal for Clinical Oncology found that higher out-of-pocket costs were associated with increased rates of delayed initiation and abandonment of insurer-approved prescriptions for a new course of therapy with a novel oral anticancer agent.
Almost half the patients who faced out-of-pocket costs of more than $2000 for their first prescription, abandoned their approved oral anticancer prescription at the pharmacy.
“Certainly, any delay in initiating cancer treatment delays [successful] outcomes,” Doshi said. “Because of the patient assistance program exclusions, we are seeing delays in patients starting on medication, and that delay in starting treatment or having access to treatment has a negative impact on their disease and on their life.”
Is There an Answer?
Although the oncology community has issued sharp criticism against insurers and the third-party companies behind the copay and alternative funding programs, there has been no overarching solution so far.
In some cases, drug companies have taken legal action against third-party vendors for allegedly taking advantage of their assistance programs.
In 2023, Johnson & Johnson filed a lawsuit against SaveOnSP, a copay assistance program. SaveOnSP is run by Express Scripts, a pharmacy benefit manager owned by health insurance giant Cigna, and works with specialty pharmacy Accredo Health Group, Inc.
In the suit, Johnson & Johnson claimed the copay assistance program had been inflating copays for certain medications and then billing Johnson & Johnson’s copay assistance program, Janssen CarePath.
Inflating patient copays ultimately reduces what health insurers pay for these drugs and “extracts patient assistance support away from Janssen CarePath for the financial benefit of SaveOnSP and its partners,” according to the suit.
AbbVie filed a similar lawsuit against the alternative funding plan, Payer Matrix, in 2023 in the US District Court for the Northern District of Illinois. In that case, AbbVie alleged Payer Matrix employs a fraudulent scheme that exploits AbbVie’s charitable assistance program.
Payer Matrix has denied the allegations and contends it’s a “pioneering advocacy organization” that partners with employer groups nationwide to “mitigate the financial risk associated with the ever-rising costs of these types of drugs,” according to court documents.
Oncologists and patient advocates say alternative funding programs are more challenging to regulate but some states have passed copay accumulator legislation. At least 19 states, the District of Columbia, and Puerto Rico have laws requiring insurers to count copay assistance toward patients’ deductibles. And in 2024, Tennessee proposed legislation that would prohibit insurer, pharmacy benefits manager, or a third party from altering health insurance coverage benefits based on the availability of financial assistance for a prescription drug.
“We have tried to bring awareness at the state legislature levels, and we actively continue to work through societies like Community Oncology Alliance and with our health policy leadership through US Oncology,” Doshi said. “But we’re the ones speaking out on behalf of patients. The burden is too much to put on the backs of cancer patients.”
When it comes to naming the dietary patterns offering the most protection against cancer, plant-based diets emerge as the winner for reducing the risk for several cancers sensitive to lifestyle factors.
Though most research into dietary patterns over the past few decades has compared the Mediterranean diet with the Western diet, meta-analyses in the past 5 years have brought more attention to the benefits of plant-based diets. One of the leading hypotheses for the association between plant-based diets and reduced risk for certain cancers is how eating diverse plants affects the microbiome.
Most recently, for example, a study published on January 6 in Nature Microbiology compared the microbiomes of vegans, vegetarians, and omnivores across five cohorts totaling 21,561 individuals. Omnivores had more bacteria linked to increased risk for colon cancer, the researchers found, and microbes with favorable cardiometabolic markers were particularly plentiful in vegans’ microbiomes. But those healthy microbes in vegans also appeared in greater amounts in the microbiomes of omnivores who ate more plant-based foods. That finding suggests eating a diet emphasizing plants may be more helpful for preventing cancer than cutting out meat.
Decades ago, the idea that changing lifestyle behaviors could have an impact on cancer risk was so radical that many dismissed it as “false hope” sold by “snake oil salesmen,” according to Nigel Brockton, PhD, the vice president of research at the American Institute for Cancer Research (AICR). Today, it’s far better understood that lifestyle factors play a major role in many different cancers, but researchers are still working to disentangle precisely how. Nowhere is that more complex than with diet, suggested experts.
“Particularly over the last 10 years, there’s been a push in the research for [investigating] dietary patterns rather than individual foods or macronutrients,” Brockton said. The problem is, “if you just tell someone to eat a healthy diet, that means different things to many different people.” But as the evidence accumulates, it increasingly points to one over-arching theme: More plants, less cancer.
Defining ‘Plant-Based Diets’
The AICR promotes a plant-based diet based on the totality of evidence in its most current expert report on lifestyle factors and cancer. But a major research challenge in determining how protective plant-based diets might be in preventing certain cancers is the nebulous definition of “plant-based.”
Elizabeth A. Platz, ScD
“Plant-based diet is actually an umbrella term that covers many different diet patterns,” said Elizabeth A. Platz, ScD, a professor of cancer epidemiology at Johns Hopkins Bloomberg School of Public Health, Baltimore. “There’s not a checklist.”
Indeed, the AICR notes the multiple types of diets that fall under the plant-based umbrella. Instead of a checklist, they promote the “New American Plate,” composed of at least two thirds of vegetables, fruits, whole grains, and beans, and no more than one third of animal protein.
“There is no one definition of ‘plant-based diet’,” Anne McTiernan, MD, PhD, a professor of epidemiology at Fred Hutch Cancer Center, said. “Diets with a lot of vegetables and fruits, low in refined carbohydrates, and relatively low in saturated fats are ‘good’ in terms of reducing risk for obesity and at reducing risk of some cancers,” she continued. “However, no one diet stands out as ‘the diet’ one should follow.”
Carrie Daniel-MacDougall, PhD, MPH
Carrie Daniel-MacDougall, PhD, MPH, an associate professor of epidemiology at The University of Texas MD Anderson Cancer Center in Houston, said AICR’s definition is more of a “plant-forward” diet.
“It doesn’t have to be entirely vegan or vegetarian. It just means you’re eating more plants than anything else,” she said. Having plants provide most of a person’s daily calories is a part of healthy diets of many different names, including the Mediterranean diet.
“From a research perspective and a public health perspective, we are pushing the same things every time,” Daniel-MacDougall said. “We’re just trying to get people to grasp it and do it.” Hearing “Mediterranean diet” may lead some to think only of hummus and parsley salad, or food that’s exotic or unfamiliar, she suggested. “Maybe ‘plant-based diet’ sounds more flexible, and they can fit that within what they already know and understand.”
Another way to think about a plant-based diet is to move the focus of a meal away from meat being the central item, Platz said. Instead of eating meat as the main course with sides, “consider other sources of protein and make sure there’s plentiful, colorful fruits and vegetables,” she said.
“Although the term plant-based is used, these are not vegan or vegetarian diets,” Edward Giovannucci, MD, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, Boston, said. “Individuals scoring highly on the healthy plant-based index still tend to eat ample amounts of animal-based foods, though they tend to be healthier, especially lower fat versions of meat and dairy.”
What Research Findings Show
The vast majority of research assessing cancer risk and diet patterns focuses primarily on the Mediterranean diet, particularly as compared with a Western diet. But in the past 5-10 years, more studies have been zeroing in on vegetarian or mostly-plant-based diets, and enough evidence has accrued to draw several broad conclusions.
Digestive system cancers, including cancers of the esophagus, stomach, colon, rectum, liver, and possibly pancreas, appear to be the cancer types where plant-based diets are most beneficial for reducing risk, Edward Giovannucci, MD, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, said. They also might be protective against breast and prostate cancer, but again, evidence is still accruing, Giovannucci said. One 2023 study, for example, found plant-based diets reduce risk for recurrence of prostate cancer.
The most recent research uses different indices to assess dietary patterns without specifying the amount of animal-based foods that participants consumed. A 2023 meta-analysis included assessment of 22 prospective cohort studies on cancer with 57,759 participants and found greater adherence to a plant-based diet was associated with a 12% reduced risk for cancer, driven primarily by associations in reduction of breast, pancreatic, and prostate cancer. The benefit increased slightly to a 14% reduced risk when the dietary pattern emphasized healthy plant-based foods in particular, including vegetables, fruits, whole grains, and legumes. Those were studies that used the “healthful plant-based dietary index” instead of the “overall plant-based dietary index.” In fact, higher adherence to an “unhealthful plant-based dietary pattern” was linked to a 7% increased risk for cancer.
For specific cancers, plant-based diets were associated with a 9% reduced risk for breast cancer, a 13% reduced risk for prostate cancer, an 18% reduced risk for digestive system cancer, and 32% reduced risk for pancreatic cancer. Meanwhile, associations for colorectal, liver, lung, and stomach cancer did not reach significance. But with fewer studies looking at these cancers, there may simply not have been enough statistical power to reach significance. And, when researchers looked only at a healthful plant-based dietary pattern, colorectal cancer risk fell by 15%.
In exploring potential mechanisms for the associations, the authors noted the link between obesity and cancer and the fact that healthful plant-based dietary patterns tend to be low in energy density and saturated fat but high in fiber, which helps with both weight loss and maintenance. Plant-based diets also involve little to no consumption of red and processed meats, which are linked to higher risk for breast, colorectal, and lung cancers. That link is hypothesized to result from inflammation, oxidative stress, and dysfunctional insulin signaling from nitrates, heme iron, and other inflammatory components, according to a research review of the mechanisms that may explain the association. Plants, on the other hand, tend to have more anti-inflammatory and anti-oxidative effects that can interfere with cancer development.
Another 2023 meta-analysis of eight studies with 686,691 participants investigated potential links between vegetarian diets and gastrointestinal cancers. Vegetarians had a 23% lower risk for gastrointestinal cancers than non-vegetarians. More specifically, gastric cancer risk was 58% lower and colorectal cancer risk was 15% lower, but upper gastrointestinal cancer risk, except stomach, was not statistically different between the groups. A gender difference also emerged, with men showing a 43% reduced risk for overall gastrointestinal cancers but women showing no significant correlation. The risk reduction was also greater in Asian populations (57% lower) than in North American ones (24% lower).
Though still modest, the literature on different subtypes of plant-based diets or on specific cancers is growing. One 2023 meta-analysis of 10 studies narrowed the focus to plant- vs animal-based low carbohydrate diets. Cancer mortality was 14% higher with overall low carb diets and 16% higher with animal-based low carb diets. The plant-based low carb diets were associated with a lower risk for all-cause mortality, but they were not associated in either direction with cancer risk.
A 2022 meta-analysis of 49 studies and a little over 3 million participants looked only at digestive cancers and found an 18% lower risk for cancer among the cohort studies and a 30% lower risk among the case control studies with plant-based diets. Pancreatic cancer was 29% lower, colorectal cancer was 24% lower, rectal cancer was 16% lower, and colon cancer was 12% lower. There was no difference between risks with plant-based diets and vegan diets.
Earlier studies had focused specifically on vegetarian and vegan diets, which implied that participants following these patterns consumed no meat at all. A 2012 meta-analysis of seven studies found that vegetarians had an 18% lower risk for cancer than non-vegetarians. Similarly, a 2017 meta-analysis of 86 cross-sectional and 10 prospective cohort studies found an 8% reduced risk for cancer among vegans and vegetarians compared with omnivores, though no associations showed up for specific types of cancers.
But a shift appears to have occurred in the late 2010s, when researchers began looking not solely at vegetarian and vegan diets but at diets that were predominantly comprised of plants. An early meta-analysis in 2017, for example, did not specify “vegetarian” in comparing “plant-based” patterns to others. The analysis of one prospective cohort (492,306 participants) and six case control (10,558 participants) studies included four studies on colorectal cancer, two on gastric and esophageal cancers, and one on breast and ovarian cancer. Compared with high plant consumption diets, high meat consumption diets had a 64% increased risk for cancer. Compared with a mixed dietary pattern, plant-based diets had a 12% lower risk for cancer.
Identifying the Mechanisms
To some extent, the mechanisms for how plant-based diets can reduce risk for certain cancers isn’t a mystery, Platz said.
“It turns out, this strategy for eating, whether you follow more of a vegan version or an ad hoc version cobbling together things that are more plant-oriented, is just healthier in general,” she said. Plant-based diets “tend not to have ultra-processed foods, and they tend to be better for blood sugar because they have more fiber. They’re healthier ways of living that could reduce the risk of many chronic diseases, including diseases that themselves are risk factors for cancer, so ultimately they’re also useful for avoiding cancer.”
But there are some specific mechanisms that may play a role, she said. For example, H. pylori is an established risk factor for stomach cancer, and high sodium levels encourage the growth of the bacteria, thereby exacerbating the risk for gastric cancer. Salt is commonly used to preserve meat, so eating less meat can result in lower sodium intake.
Plant-based diets also tend to keep blood glucose low, and many plants are known to be anti-inflammatory, whereas high-sugar diets increase insulin, a growth factor, Platz said. Growth factors have long been implicated in cancer development.
Perhaps the simplest mechanism is the fact that plant-based diets are associated with lower overall caloric intake, thereby reducing risk for obesity, Brockton said. “Probably in the next 10 years, obesity will overtake smoking as the predominant risk factor for cancer,” he said.
Another likely mechanism that has been accruing more evidence is the role of a diverse plant-filled diet in promoting a healthy microbiome, both from increased fiber and from various phytochemicals.
“The microbiome has an impact on the immune system, so a healthier, more diverse microbiome leads to a healthier, more diverse immune system,” Brockton said. “They’re even showing that people with higher fiber intakes have better responses to immunotherapy in melanoma.”
While there is not enough evidence to link greater diversity of plant intake with reduced cancer risk, evidence does show that “people who eat a more diverse array of plants tend to have a more diverse microbiome,” Brockton said, and there’s increasing evidence that microbiome diversity is linked to survival with certain cancers. “That’s why the advice is to eat a range of fruits and vegetables, and that tends to offer the greatest benefit,” Brockton said.
It’s also true that those who eat a diet heavier in plants tend to exercise more, smoke less, and drink less — all behaviors that reduce cancer risk. Despite that correlation, “the diets seem to be beneficial independently,” Giovannucci said. “For example, we see protective associations in smokers and nonsmokers, in alcohol drinkers and nondrinkers, in overweight/obese and in lean individuals, in active and in sedentary people.”
Food Quality Matters
Of course, not all plant-based diets are created equally. It would be easy to fill a diet with French fries, potato chips, and doughnuts and call it plant-based, but no one would mistake that diet for helping to prevent cancer.
“It’s important to distinguish between an overall plant-based diet and a healthy plant-based diet,” Giovannucci said. A healthy plant-based diet, for example, positively weights whole grains, fruits, vegetables, vegetable oils, nuts, and legumes, and it negatively weights refined grains, fruit juices, potatoes, sugar-sweetened beverages, and sweets, he explained.
One of the most helpful collations of risk is an evidence matrix developed by the AICR and the World Cancer Research Fund. It uses color coding to indicate the likelihood of increased or decreased risk for specific cancers and the strength of the evidence for that likelihood for over two dozen subgroups of foods, such as red meat, citrus fruits, non-starchy vegetables, whole grains, or vitamin C-rich foods. More evidence suggests a decreased risk with non-starchy vegetables for about a half dozen cancers, for example, than most other subgroups. The matrix also includes 15 dietary patterns or diets rich in particular components, such as beta carotene, retinol or saturated fatty acids.
A different, and more patient-friendly interactive cancer matrix from the same two organizations allows users to mouse over bubbles whose size correlates with effect size on risk. In each bubble, users can read more details about each component of a diet.
Daniel-MacDougall pointed out that food manufacturers frequently grab onto buzzwords that seem trendy so they can use it in their marketing. But just because something is “plant-based” doesn’t mean it’s unprocessed, and some plants can be ultra-processed into a form that’s no longer healthy. “A plant-based diet could be unhealthy if you’re getting all of it off a shelf,” she said.
How to Advise Patients
With the limited time providers have with patients, delving into diet may seem an impossible task. But Daniel-MacDougall advises clinicians to find out where patients are starting from before offering advice. That doesn’t have to mean requesting a detailed food diary but simply asking what their typical breakfast, lunch, and dinner look like. Providers can then meet patients where they are. If they stop by a convenience every morning for breakfast, help them figure out what they can pick up at that store that’s healthier than their usual.
“Some people have more or less freedom or resources in their lives to make those decisions and changes,” Daniel-MacDougall said. She also suggests that clinicians offer patients more than one form of healthy diet, or more than one strategy for eating more plant-based foods. One way to do that is to focus on one goal at a time, starting with, for example, increasing fiber intake.
“While you’re working on that, you’re going to increase your plant foods by default because you don’t get fiber from animal foods,” she said. “But it’s also going to help you identify plant foods that are higher quality and less refined because those provide more fiber.”
Platz echoed this strategy, suggesting small shifts rather than radical diet makeovers. Incremental steps are particularly helpful for people who are time-poor. One such step could be eating a smaller serving of meat while doubling a vegetable serving, or adding a leafy vegetable or colorful berries.
“These diets should be viewed as aspirational,” Platz said. “People can make changes, moderate, and move in that direction.”
Daniel-MacDougall, Platz, Giovannucci, McTiernan, and Brockton had no disclosures.
