Are there more prostate cancer diagnoses just because there are more screenings?

It’s a classic chicken/egg conundrum. Men with a family history of prostate cancer are thought to be more likely to develop the disease themselves, so it is recommended they get screened for the disease more often.

But frequent screenings make it more likely a prostate tumor will be found -- including tumors that are not dangerous. So are those men with a father or brother with the disease more likely to have a tumor diagnosis because of genetics -- or because they are more likely to be screened? A new study from Sweden released Thursday suggested that the answer was: a little bit of both.

The lifetime risk of a man dying from prostate cancer is about 3%, a proportion that has remained constant for at least three decades. But during that same period, the lifetime risk of being diagnosed with prostate cancer has nearly doubled, from about 9% to 16%, largely as a result of increased screening. That screening has become increasingly controversial.

Studies have shown that screening, mostly using the prostate-specific antigen (PSA) test, has increased the number of cancer diagnoses, the number of biopsies and other surgical procedures and the number of complications from those procedures while failing to lower the mortality rate. The fact is, most elderly men have prostate tumors that are harmless. And most prostate tumors themselves are harmless and can be safely ignored.

But researchers currently have no ready way to distinguish between those that are safe and those that are aggressive and will become life-threatening, so when a tumor is observed, it is most often treated -- with all the expense and complications that entails. The American Cancer Society and other groups are now urging physicians to make a greater effort to inform men of all the potential risks associated with screening.

Dr. Ola Bratt, a urologist at the Helsingborg Hospital in Sweden, and colleagues analyzed data on 22,511 brothers of men with prostate cancer and 13,975 prostate cancer patients in Sweden’s National Prostate Cancer Registry. They reported online in the Journal of the National Cancer Institute that men with a brother or father who had been diagnosed with prostate cancer had three times the normal risk of being diagnosed with a tumor themselves. Most of that increased risk, however, was attributable to finding low-grade non-aggressive tumors of the sort that would never be found and never produce symptoms if doctors didn’t go looking for them.

The risk of such a diagnosis was 4.3 times as high in the first year after a family member had been diagnosed, again suggesting a role for testing. The risk also was higher for men of higher socioeconomic status, who were more likely to seek testing.

The Swedes could not determine precisely what proportion of the purported familial link to prostate cancer was due to so-called detection bias, caused by increased testing of family members of those with the disease, but they concluded that it was definitely contributing to the observed increase in risk.

In an editorial accompanying the study, researchers from the University of Texas Health Science Center in San Antonio concluded that “perhaps the best tactic would be to change our approach from seeking risk factors for prostate cancer (a disease that is ubiquitous, with many patients probably being better off if it were not detected by screening) to an assessment of factors related to biologically consequential prostate cancer (i.e., metastatic disease or prostate cancer-specific death).”

-- Thomas H. Maugh II / Los Angeles Times