Should You Have Your Blood Tested for Cancer?

 by Devon Herrick

Cancer runs in my family. A paternal uncle died of pancreatic cancer 50 years ago. Two of my aunts (his sisters) also died of cancer. I have a maternal aunt who died of colon cancer. Others in my family detected cancer early and were successfully treated. 

Due to my family history of cancer, I have had my blood tested for cancer markers. I purchased OneTest™ for cancer in 2025. The test results indicated that I only had a 1-in-200 probability of being diagnosed with common cancers within the next 12 months. During my May 2026 blood chemistry panel, I paid $200 extra to screen for common cancer markers. Call me paranoid, but there are numerous other things people spend money on of less value than knowing I probably do not have cancer.

Some cancers are hard to detect. Pancreatic cancer is one that manifests few if any symptoms before it becomes incurable. Many cancers require invasive or costly tests. I recently had a colonoscopy, the primary purpose of which was to prevent or diagnose colon cancer. Many cancers do not even have reliable screening tests. A single test that can screen for multiple cancers from a few drops of blood would be a huge benefit. Multiple companies are developing such tests. 

A while ago I wrote about Grail, a blood test for 50 different cancers. Although it has not been officially approved by the FDA, it nonetheless has been on the market for several years. The Wall Street Journal reports Grail is scheduled to be reviewed by an FDA outside advisory committee this week:

Grail’s Galleri test leads a fast-developing field of liquid biopsies that screen asymptomatic patients for signals of cancer in blood. The goal is to diagnose cancers earlier when they are easier to treat, and the odds of survival are higher.

In development for a decade, Galleri looks for DNA shed by cancer cells. The DNA is tagged by molecules specific to a cancer’s origin—say, the colon or pancreas. Grail uses genetic sequencing and machine learning to recognize links between these DNA signatures and particular cancers.

 The WSJ Editorial Board concludes with: 

“…let’s hope bureaucrats don’t get in the way.”

This is where the WSJ editorial goes off the rails. Grail’s Galleri is already on the market. Your doctor can order it right now. Even if the FDA advisory committee decides not to recommend approval the test (and others like it) will continue to be available under a different regulatory pathway. The WSJ Editorial Board accuses FDA officials of stalling approval of these types of tests due to a type of cost/benefit rationing. The WSJ editorial is not about access; it is about insurance coverage. Seeking FDA approval is all about who must pay. 

Under the Affordable Care Act health plans must pay for preventive screening tests that are recommended by the U.S. Preventive Services Task Force with a letter grade of A or B. Galleri is unlikely to meet that threshold. However, that does not mean a test for 50 different cancer DNA markers is not valuable. It just means the test may not be cost effective when used on a broader population. 

How good is it? Estimates vary but like most of these tests Galleri is better at detecting advanced cancers than early-stage cancer (when it is most curable). The online physician community Sermo estimates Galleri’s sensitivity is only about 17% for Stage I cancers; 40% for Stage II, 77% for Stage III and 90% for Stage IV. Grail claims it will identify aggressive cancers earlier than less aggressive cancers. Grail also claims Galleri’s false positive rate is extremely low, a crucial factor for wider adoption. Doctors remain skeptical, but also optimistic. 

Grail’s multi-cancer Galleri test has the potential to be a huge advancement in cancer detection. However, some experts want more data before recommending widespread adoption. That does not mean you should not get it. I will probably take the Galleri test sometime in the future. I do not need insurance coverage, FDA approval, or the Preventive Services Task Force recommendation to decide whether it is worth the $799 cost. From a cost/benefit analysis it makes little sense for Medicare or private insurance to pay for such a test. Yet, people like me who are willing to pay for peace of mind should have the option of paying out of pocket. There is nothing wrong with that.

https://www.goodmanhealthblog.org/should-you-have-your-blood-tested-for-cancer/