03:30pm Saturday 14 December 2019

Stanford experts question new guidelines that recommend fewer mammograms

Norbert von der Groeben description of photo

Debra Ikeda spoke Feb. 24 on why she favors annual mammograms starting at age 40 instead of doing them less-frequently and starting at a later age.

The latest version of the guidelines, released last November by the U.S. Preventive Services Task Force, would delay a woman’s first mammogram by 10 years, reduce future screenings from annual to every other year, and end them after age 74.

Instead, presenters for the Feb. 24 program, “Controversies in screening for women’s cancer,” said they’ll continue to support the 2003 breast-cancer screening guidelines from the American Cancer Society, which call for annual mammograms starting at age 40.

The new guidelines apply only to women at average risk for breast cancer, not high-risk women.

Debra Ikeda, MD, director of Stanford University Breast Imaging, said she disagreed with the task force’s conclusion that the number of lives saved by annual mammography screening for women in their 40s was outweighed by the risks of screening for that age group. “Women need to know that [with routine mammograms] there may be false positives and a need for biopsies,” she said. “But women should make that choice for themselves, with a doctor’s help.”

Ikeda, professor of diagnostic radiology, is concerned that the new guidelines will lead to some women missing out on a cancer being detected early, when it’s more treatable. “With that longer interval between mammograms,” she said, “we’ll start seeing more higher-stage cancers.”

While possible over-diagnosis of breast cancer is also a risk of routine mammograms, Ikeda said, “the problem I have is, how do I know which cancer is going to kill a woman and which one won’t? I don’t want to take that chance.”

The real problem, she said, is there is no reliable test to distinguish deadly breast cancers from those that won’t cause harm. Also, she said the actual benefit of annual mammograms for women in their 40s is likely greater than the USPSTF determined, since its data couldn’t have fully reflected recent advances in breast imaging technology. Professional societies, including the American Cancer Society and the American College of Obstetricians and Gynecologists, also oppose the new breast-cancer screening guidelines and back the previous guidance.

Professor of medical oncology Robert Carlson, MD, also a presenter at the program, said he, too, supports the older guidelines. He said he is particularly concerned that the new guidelines could lead insurers to limit coverage of breast cancer screening.

Still, Carlson said the task force’s new breast cancer guidelines represent a difference in opinion and values. From a policy perspective, he said, screening every two years starting at age 50 could be considered reasonable given the need to use limited resources for the greatest benefit. Annual screening starting at age 40 would require approximately 50,000 women to be screened, and millions of dollars spent, for every life saved, he pointed out.

The new guidelines also recommend against teaching women to perform self-exams, and they question the value of clinical breast exams.

Carlson said that discouraging breast self-exams may seem counterintuitive because many women discover their breast cancer this way. But results from large, randomized controlled trials, including a study of 250,000 textile workers in Shanghai, have shown that doing self-exams does not increase cancer detection rates and does not decrease mortality rates. Instead, studies found that the women in the breast self-exam group had significantly more biopsies than the control group, but the number of cancers found and the number of breast cancer deaths was similar in both groups.

Based on this evidence, Carlson said he no longer advises women to do breast self-exams, though he won’t discourage the practice if a woman wants to do it.

The USPSTF’s report found insufficient evidence to support breast exams performed at a doctor’s office. Carlson said he favors continuing the practice until further data is available.

The program presenters predicted that the guidelines will likely be revisited as further evidence is collected. “It’s critical that we study this more and we study it carefully,” said program moderator Jonathan Berek, MD, director of the Women’s Cancer Program at Stanford, and professor and chair of obstetrics and gynecology. Meanwhile, he said, “It’s critical that we don’t have limits on our resources while this gets sorted out.”

Stanford University Medical Center integrates research, medical education and patient care at its three institutions – Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children’s Hospital. For more information, please visit the Office of Communication & Public Affairs site at http://mednews.stanford.edu/.

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