All this is happening against the backdrop of recent articles questioning the conventional wisdom that screening and early treatment reduce deaths from breast and prostate cancer. I've always assumed I should submit in good grace to frequent mammograms, and that sensible men would get P.S.A. tests. It turns out there's real doubt whether there's any point to the early diagnoses and the treatments they inspire. In the case of breast cancer,As noted by H. Gilbert Welch of the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, N.H., and author of "Should I Be Tested for Cancer?", this is the "overdiagnosis paradox":
mammography is an inefficient method for detecting breast cancer. It’s much better at finding the indolent cancers that would have never caused harm than it is at finding the nasty, aggressive ones most helped by treatment. Statistics show that for 2,000 women screened by mammography over 10 years, one will be prevented from dying of breast cancer and 10 others will receive treatments for a cancer that would have never become life-threatening. That means that screening causes 10 times as many women to become cancer patients unnecessarily as it prevents from dying from breast cancer.
“The more overdiagnosis the test causes, the more popular it is because there are more survivors,” he says. “The person who had a breast cancer diagnosed by mammography is tempted to view herself as being helped, but there are two other possibilities that are more likely,” he says. The first is that the person would have fared exactly the same without the mammogram, and the second is that the cancer the mammogram diagnosed was indolent and did not require treatment. “I always hope that the person who found cancer via mammography was helped,” says Welch, but on an individual level it’s impossible to say which category an individual person falls into. Statistically, the vast majority fall into the overdiagnosed category.In other words, it's entirely possible that the women who survived breast cancer would have been fine even without the treatment, and that those who didn't get well had the sort of cancer that no treatment would have helped anyway. A similar picture emerges for prostate cancer and the P.S.A. test. Undiagnosed prostate cancer is so common that "[a]utopsy studies show that a third of men ages 40 to 60 have prostate cancer, a share that grows to three-fourths after age 85."
“Unfortunately, the evidence now shows that [the P.S.A] test does not save men’s lives,” said Dr. Virginia Moyer, a professor of pediatrics at Baylor College of Medicine and chairwoman of the task force. “This test cannot tell the difference between cancers that will and will not affect a man during his natural lifetime. We need to find one that does.”If you'd like to think that modern medicine can delay certain kinds of death, this is bad news. If you're inclined to be fatalistic and to place strict limits on the degree to which you'll let aggressive medicine invade your life, it's actually pretty great. As the author of the article on prostate cancer suggested,
. . . [T]here is little doubt that [the P.S.A. test] helps identify the presence of cancerous cells in the prostate. But a vast majority of men with such cells never suffer ill effects because their cancer is usually slow-growing. Even for men who do have fast-growing cancer, the P.S.A. test may not save them since there is no proven benefit to earlier treatment of such invasive disease.
Not knowing what is going on with one’s prostate may be the best course, since few men live happily with the knowledge that one of their organs is cancerous.Ditto, perhaps, for women and the breast cancer they may be harboring unawares. I've often thought there were medical conditions about my own body I'd just as soon not know about any sooner than I have to, particularly if the only treatment for them would be horrible, expensive, and only ambiguously effective.