Dr. Patrick Walsh, a professor of urology at Johns Hopkins, argued that the prostate study is deeply flawed.
"The problem with the article is simple," he said. "In 1986 there was an enormous reservoir of men in the population with advanced asymptomatic incurable prostate cancer -- so that when they were diagnosed with cancer, treatment had no effect on their outcome. Then, beginning in the mid- to late-1990s, we finally were seeing men who were curable and who were going to live long enough to be cured."
The study does not show, said Walsh, any benefit for the patients who were diagnosed at the end of the study period, since the 15 to 20 years it might take some patients to die (from a slow-growing tumor) has not yet passed.
Dr. Marisa Weiss, the founder of breastcancer.org, had similar criticisms of the breast cancer study for not highlighting the benefits of clinical breast exams -- although she noted that part of the issue was the difference between the American and Canadian healthcare systems.
The Canadian study, she noted, may have only included one exam for most of the women involved, since it only lasted two years, she said, and the medical professional doing the exam may not have been the woman's regular doctor.
"When you're doing your first study and you know you're going to be examining that person once…you might be more likely to find something or check something out than if you had an ongoing relationship with that person and you knew you'd be seeing them again at a short interval," said Weiss.
That would contribute to a high rate of false positives, she said.
"Doctors and nurses could benefit by further training…but I do think the risk of false positives is decreased by regular repetition," said Weiss.
Like the study author, she thought the study showed that more emphasis should be placed on having a standardized breast exam. But she did not agree with another conclusion of the study.
"There's a lot at risk because 20 percent of breast cancers are detected by the women or doctor, not detected mammographically," said Weiss. "I'm very worried about a result that would give up the opportunity for women to find breast cancers earlier than they would be detected by mammogram alone."
In his editorial, Brawley noted that part of the problem with the emphasis on screening is that it has drawn funding from other areas.
"Indeed, over the past 20 years, many research dollars were spent addressing the question 'how can men be encouraged to get screened?' when projects to better understand prostate cancer biology were not funded," he said.
Several doctors noted that given the wide variety of diseases that make up any one form of cancer, more research was needed to determine the best way to tackle a growth in a particular patient.
"Like any screening test, the results have to be interpreted," said Dr. Scott Fields, a family practitioner with Oregon Health and Sciences University. "In this case, it is very problematic because prostate cancer often is present but causing no problems. And we really have little way of differentiating people who will be affected."
In a twist, it appears that while studies may have focused on finding ways to increase screenings, many more are looking at the possible impacts of false positives.