Why I Won't Get a Colonoscopy
I recently visited a doctor for one problem, and, as doctors are wont to do, he recommended tests for completely unrelated problems. My hearing has seemed muffled lately, so I wanted the doctor to peer in my ears. He said my ears looked fine; I'm probably just experiencing normal, age-related hearing decline. (Delayed effects, no doubt, from sitting in the front row during a Jimi Hendrix concert in 1968.)
The doctor asked me when my last check-up was. Five years ago, I said, after I got a sports hernia playing hockey, but I feel fine. He nonetheless recommended a blood test for high cholesterol and other potential problems, a PSA test for prostate cancer and maybe a screen for colon cancer. No thanks, I said coldly, and left his office. Little did he know he was talking to an anti-testing nut.
As I reported last fall, men are 47 times more likely to get unnecessary, harmful treatments—biopsies, surgery, radiation, chemotherapy—as a result of receiving a positive PSA test than they are to have their lives extended, according to a major study.
As for screening for colon cancer, a new study allegedly finds merit in colonoscopies, a nasty, expensive procedure in which a physician sticks a cable tipped with a camera and clippers up your butt and snips off suspicious-looking lumps on the wall of your bowels. The study, published in the New England Journal of Medicine, involved 2,602 patients tracked for up to 23 years after they had colonoscopies resulting in the removal of polyps. Twelve people in this group died of colon cancer, compared to an average of 25.4 people in the general population.
A New York Times editorial proclaimed that the study "ought to goad millions who are still ducking [colonoscopies] to get over their squeamishness." The study ought to do no such thing. First of all, it was not a randomized clinical trial. The screened group might have been healthier to begin with than the non-screened group.
Second, the study looked only at death from colon cancer and not from all causes. The physician James Penston, a consultant to England's National Health Service, argued in the British Medical Journal last October that all-cause mortality is a better measure of the value of screening, both because attributing cause of death can be unreliable and because screening itself can be harmful.
"Invasive procedures may have fatal complications, while overdiagnosis—that is, the identification and treatment of tumors that otherwise would have caused no disease—may also result in death," Penston stated. According to Penston, meta-analysis of four randomized trials involving 300,000 people found that tests for bowel cancer did not reduce overall mortality rates.
Another analysis of British data on colon cancer, by the watchdog group Straight Statistics, concluded that screening 1,000 patients for 10 years will prevent two deaths from the disease. Meanwhile, colonoscopies lead to "serious medical complications" in 5 out of every 1,000 patients, according to a 2006 report in the Annals of Internal Medicine. Given these risks, my guess is that a rigorous examination of colonoscopies will find that their benefits do not outweigh their downside.
The New York Times, perhaps to offset its ill-considered editorial plug for colonoscopies on February 24, ran a rebuttal of sorts three days later from H. Gilbert Welch, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice and author of Overdiagnosed: Making People Sick in the Pursuit of Health (Beacon Press, 2011). Welch wrote:
"Screening the apparently healthy potentially saves a few lives (although the National Cancer Institute couldn’t find any evidence for this in its recent large studies of prostate and ovarian cancer screening). But it definitely drags many others into the system needlessly—into needless appointments, needless tests, needless drugs and needless operations (not to mention all the accompanying needless insurance forms). This process doesn’t promote health; it promotes disease. People suffer from more anxiety about their health, from drug side effects, from complications of surgery. A few die. And remember: these people felt fine when they entered the health care system."
Now that's a healer who adheres to the ancient precept: First, do no harm. The next time a doctor urges me to get unnecessary tests, I'm going to email him Welch's essay.
Sign up for Scientific American’s free newsletters.
Image courtesy Wikimedia Commons.
Sem comentários:
Enviar um comentário