The American Cancer Society is delaying the recommended age when a woman should start receiving annual mammograms, based on new research that shows the average risk for breast cancer increases near menopause.
Most women should receive annual mammograms between the ages of 45 and 54, then transition to screening every two years for as long as they remain healthy, according to the new breast cancer screening guidelines.
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The guidelines are more conservative than the American Cancer Society's previous approach, which recommended yearly mammograms starting at 40 and continuing as long as a woman is in good health.
The cancer society shifted its guidelines, in part, because it started looking at breast cancer risk in five-year increments, rather than considering women in their 40s versus women in their 50s or 60s, said lead author Dr. Kevin Oeffinger. He is chairman of the American Cancer Society (ACS) breast cancer guideline panel and a family physician at Memorial Sloan Kettering Cancer Center in New York City.
"We found that women who are 45 to 49 are very similar to women 50 to 54 with respect to the burden of cancer, the risk of dying from cancer and the reduction in mortality from mammography," Oeffinger said. "That helped us in our thought process. We felt the evidence is very clear."
Read: Mammogram guidelines revised - again
The new guidelines are published in the October 20 issue of the Journal of the American Medical Association.
With this announcement, the new cancer society guidelines move closer to those of the US Preventive Services Task Force (USPSTF), which is the nation's leading panel of experts in preventive medicine.
The USPSTF received some criticism back in 2009 when it recommended that most healthy women without increased breast cancer risk wait until age 50 to begin mammography, and then undergo the procedure every other year.
"In some ways they converge a bit more than they did in the past, especially in terms of the ACS pulling back a bit and recommending a slightly later date for mammography screening," said Dr. Lydia Pace, a women's health specialist at Brigham and Women's Hospital in Boston, who co-authored an accompanying journal editorial about the new guidelines.
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For its part, the USPSTF issued a statement noting the similarities between its recommendation and the new cancer society guidelines.
"We plan to examine the evidence that the ACS developed and reviewed as we finalize our own [updated] recommendations on mammography," the task force said. "Women deserve the best information and guidance on screening mammography so that they can make the best choice for themselves, together with their doctor."
Under the new guidelines, the cancer society recommends that:
- Women 40 to 44 discuss mammography with their doctor, and have the option of starting annual screening if they want it or their risk factors warrant it.
- Women 45 to 54 receive annual mammography screening.
- Women 55 and older receive screening every other year, and only discontinue mammography when their life expectancy drops below 10 years.
The cancer society is shying away from saying when a woman can stop getting a mammogram, even though there isn't strong evidence on the benefits or harms of mammography past age 74, Oeffinger said.
"We know women in our country are not only living longer, but healthy and active lives," he said. "We didn't want to put a cap on the age. It's really as long as women have a reasonable likelihood of being in good health for another 10 years or so."
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The cancer society based its new guidelines on an extensive review of the current scientific evidence, including new evidence from a number of large studies, Oeffinger said.
The guidelines also are based on the results of a new study that reviewed the cases of 15,440 breast cancer patients between ages 40 and 85 that is being simultaneously published in the journal JAMA Oncology.
That study, conducted by the Breast Cancer Surveillance Consortium, found that annual mammography was better than every-other-year mammography at catching treatable breast cancers in women approaching menopause.
"Our findings suggest that menopausal status may be more important than age when considering breast cancer screening intervals," Diana Miglioretti, of the University of California, Davis School of Medicine, and coauthors concluded, noting that this is "biologically plausible" because the female hormone estrogen tends to promote tumor growth.
Read: Mammograms may not lower breast cancer death rate
Pace said of the JAMA Oncology study, "They're really trying to sort out what we know to be true, which is that although younger women have a lower absolute risk of developing breast cancer, it does appear when they do [develop cancer] some of those tumors are much more aggressive than among older women."
However, Pace does not believe the JAMA Oncology study provides enough evidence to support annual mammography for women in their late 40s.
"I think it's probably a bit early to draw the conclusion that women 45 to 54 should actually be screened more frequently than older women," she said. "They weren't able to conclude that less frequent screening led to high breast cancer mortality."
Even though the cancer society and the USPSTF are moving closer together in their recommendations, it appears that mammography screening for younger women will continue to be a controversial topic.
The American College of Radiology and the Society of Breast Imaging released a joint statement saying they will continue to recommend that women get yearly mammograms starting at age 40.
Read: Should all women be counselled before breast cancer tests?
"Early detection of breast cancer is critical for improving breast cancer survival, regardless of therapy advances," said Dr. Debra Monticciolo, chair of the American College of Radiology Breast Imaging Commission. "Moving away from annual screening of women ages 40 and older puts women's lives at risk."
Beyond mammography, the new cancer society guidelines agree with those of the USPSTF on another important topic related to breast cancer screening.
Both groups now take a skeptical stance involving clinical breast examinations, in which a trained health professional looks at and feels a woman's breasts for signs of cancer.
The ACS now recommends against clinical breast exams for breast cancer screening, regardless of age. Prior to this, the cancer society had recommended clinical breast exams every three years or so for women in their 20s and 30s, and annually for women 40 and older.
"We simply could find no evidence that suggested that clinical breast examinations were saving lives," Oeffinger said. "At the end of the day, a medical visit is kind of a zero-sum scenario. There are only so many minutes. So we felt rather than do something we don't have evidence to support, it would be very worthwhile to spend that same time discussing mammography with women."
For more on breast cancer, visit the US National Cancer Institute.
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Image: Breast examination from iStock