Ask Dr. Keith Roach M.D
Better screening tests needed for ovarian and prostate cancers
DEAR DR. ROACH: I don't know why everybody keeps debating the accuracy of the PSA test. At least it's a test that shows something. There's nothing like it for ovarian cancer. Why is that? — R.R.
ANSWER: There are several analogous tests to the PSA for ovarian cancer, and the most commonly used is called the CA-125. The CA-125, like the PSA test, was initially developed and used for monitoring the response to therapy in someone who has cancer. Both tests are useful for following the course of the disease in patients with known cancer, but are limited by the fact that there are cancers that do not have high levels of these blood markers.
Both the PSA and the CA125 have been evaluated for use as screening tests — that is, trying to find disease in someone with no known cancer and no symptoms — but they suffer from a lack of both sensitivity and specificity. They can be normal even in someone who has cancer (that's sensitivity), and especially they can be abnormal in someone who does not have cancer (specificity).
The PSA remains a hotly debated test for use in screening, but experts recommend against the CA-125 test as a screening test due to its poor specificity. Several newer tests exist, the best-studied of which is a combination of five different blood tests called the OVA1, which is more sensitive but less specific than the CA125, and which has not been evaluated as a screening tool.
We need better screening tests for both prostate and ovarian cancer. But since ovarian cancer is far deadlier than prostate cancer, finding a better blood test for early detection of ovarian cancer is even more desperately needed.
DEAR DR. ROACH: I am a 75-year-old male. A recent endoscopy disclosed that I have Barrett's esophagus with no dysplasia. I was told to take omeprazole every day to control acid reflux. My concern is that I was not told of anything that I might do to prevent Barrett's esophagus from progressing to cancer. From what I read online, it appears that omeprazole has not been found to halt this progression. Two studies for which I found abstracts report that aspirin might work, but these did not specify whether the aspirin was 81 mg or 325 mg. Please help me to understand what I can do here. — J.S.
ANSWER: Barrett's esophagus is a complication of longterm reflux of stomach acid into the esophagus, and it confers a 30-times-higher risk of developing cancer of the esophagus. However, the absolute risk of developing esophageal cancer is still small: The best estimate is that someone with Barrett's esophagus without dysplasia (early signs of transformation to cancer) would have about a 5 percent chance in 20 years.
Aspirin does seem to reduce that risk by about 30 percent. To put that another way, your chance of NOT developing cancer in the next 20 years is about 95 percent, and it would be expected to be about 97 percent if you took aspirin. The study that showed this looked at all people who took aspirin (usually 81 mg daily or 325 mg every other day). Long-term aspirin has its own risks and shouldn't be taken without consultation with your doctor.
One recent study suggested that the combination of aspirin (or an NSAID) with a statin decreased the risk of esophageal cancer by nearly 80 percent. A large trial looking at the preventive effect of aspirin is underway in the U.K. *** Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell. edu or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.