Most women need mammograms every other year starting at 50

Women at average risk for breast cancer can wait to start getting mammograms until age 50 and be screened every other year, according to new guidelines from the American College of Physicians.

Many women worry about breast cancer, but most aren’t at high risk for these tumors due to factors like a family history of breast cancer, previous cancer scares, dense breast tissue, or certain genetic mutations linked to breast malignancies. The new guidelines, published today in the Annals of Internal Medicine, are in line with longstanding recommendations from the U.S. Preventive Services Task Force (USPSFT) that recognize most women aren’t at high risk and don’t need mammograms before 50 or annual screening.

“For average-risk women, without symptoms, getting screening mammograms every year as compared to every other year did not clearly improve outcomes while it did increase harms,” Dr. Ana María López, president of the American College of Physicians, said by email.

The goal of screening mammography is to detect tumors before they can be felt in a physical breast exam, catching cancer sooner when it’s easier to treat. Ideally, this should mean fewer women are diagnosed when tumors are bigger, rapidly growing, and harder to attack.

But screening too early or too often can also catch more small, slow-growing tumors that are unlikely to be fatal - without curbing the diagnosis of advanced cancer cases, some previous research suggests. Harms of too much screening can include unnecessary invasive follow-up tests and cancer treatments for tumors that never would have made women sick or led to death, also called overdiagnosis.

“Unfortunately, we are currently unable to tell the difference between breast cancers that are over diagnosed versus the cancers that will be harmful to women, thus we recommend treatment for all,” said Dr. Joann Elmore, author of an accompanying editorial and a professor at the David Geffen School of Medicine at the University of California Los Angeles.

“Breast cancer is more common as women age and some of the harms of screening, such as false positives, are less common in older women, thus making the benefit increase and the harms reduced as women age,” Elmore said by email.

“Because of this, more national groups recommend starting screening in the 50s,” Elmore added. “When screening every year, the harms increase markedly, with less of an increase in the benefits, thus some groups now recommend screening every two years.”

For most women 40 to 49 years old, the potential harms of screening mammograms outweigh the possible benefits, according to the ACP guidelines.

Once women start getting mammograms, they should continue through age 74, the ACP recommends. After 75, or earlier for women with a life expectancy of 10 years or less, screening mammograms should stop, according to the ACP.

The American Cancer Society, however, says women ages 45 to 54 should get mammograms every year. Starting at 55, women can continue annual screening or switch to getting mammograms every other year, the cancer society advises.

It is the variation in guidelines that prompted the ACP to weigh in with recommendations of its own, said Dr. Amir Qaseem, vice president of clinical policy for the ACP.

“This highlights the critical role informed and shared decision making plays, and the need to incorporate a woman’s values and preferences in the screening decision regarding when to start screening,” Qaseem said by email.

“It is important for all women to talk to their doctor, starting at age 40, discuss benefits and harms, and share your individual values and preferences, and actively participate in the discussion and decision regarding when to start screening for breast cancer that would be best,” Qaseem advised.

SOURCE: Annals of Internal Medicine, online April 8, 2019.