Making drastic changes to U.S. breast cancer screening guidelines will take much stronger evidence than that offered by a federal advisory panel this week, U.S. doctors said on Friday.

They said the U.S. Preventive Services Task Force recommendation advising against routine mammograms for women in their 40s was a gamble many doctors are not willing to take.

The recommendations to scale back breast cancer screening touched off a fierce backlash from physicians and an outcry from women, forcing U.S. Health and Human Services Secretary Kathleen Sebelius to renounce the guidelines and assure women they did not reflect U.S. policy.

Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, rejects the notion offered by some Republican politicians that the guidelines are motivated by a push to ration healthcare.

But he said such decisions need to be based on strong evidence, especially when evidence is conflicting.

“Here we have a strategy that has been in place for 20 years and it’s worked. The task force is coming in and saying, ‘Forget the fact that it worked. We think this is the right way.’ If the science was strong, we would agree with it,” Lichtenfeld said.

“If they are right, no problem. But if they are wrong, we won’t find out for 20 years. That is the risk,” he said.

Instead of an annual mammogram starting at 40, the new guidelines call for routine screening to start at age 50 for women of average risk, and say they should been done every other year instead of yearly to balance the harms of false positive results with the benefits of saving lives.

They also recommend against teaching women to do self breast exams, because they say the evidence is not strong enough to show the practice saves lives.

QUESTIONING MODELS

One obvious concern is whether women might die of breast cancer because of the recommendations, said Dr. Thomas Herzog of Columbia University in New York, chairman of an American College of Obstetricians and Gynecologists subcommittee on gynecologic cancers.

He and others also questioned the task force’s heavy reliance on computer models instead of real-life data.

“I guess the problem, if anything, that people have is this is based on theory,” Herzog said in a telephone interview.

“It may be excellent theory. It may be the best theory out there, but nonetheless, it’s not prospective data that says how these new guidelines are actually going to perform,” he added.

“We will only know looking back if these guidelines did their job.”

Both the American Cancer Society and the American College of Obstetricians and Gynecologists stand by their current recommendations for screening mammograms to start at age 40.

Ironically, the American College of Obstetricians and Gynecologists on Friday scaled back cervical cancer screening guidelines based on studies in women that show screening women under age 21 can result in overtreatment and difficulty carrying a child full term.

Lichtenfeld said there is far more agreement on the decision to change cervical cancer screening guidelines.

And he said new evidence on the harms of prostate cancer screening, which can cause overtreatment resulting in a lifetime of impotence and incontinence, is changing two decades of screening advice for men on that cancer.

“Then you have breast cancer screening, where experts are looking at the same data and coming to markedly different conclusions,” he said.

“That is the crux of the issue.”

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* Doctors say more evidence is needed

* Some fear new guidelines would mean more cancer deaths

By Julie Steenhuysen