Knowing whether to have a mammogram — and when — became more confusing than ever last month when one of the largest-ever mammography studies cast doubts on the test’s value.
The study followed 90,000 women over 25 years and found that death rates from breast cancer were the same in women who got mammograms as in those who did not. Moreover, the study showed that one in five cancers found with mammography and then treated was not a threat to the woman’s health. That sounds like pretty resounding evidence against the test.
Yet mammography advocates such as the American College of Radiology (ACR) immediately criticized the study, calling it “incredibly misleading” and “deeply flawed.” Mammography machines used in the study, the ACR says, were not state-of-the-art and thus did not find as many cancers as the latest devices would have found.
What is a woman to make of this? Is a mammogram worth having — and if so, when?
“Mammography saves lives,” says Otis Brawley, chief medical officer at the American Cancer Society. “But it doesn’t save as many lives as the American people think it does. . . . The best studies we have suggest that two-thirds of women who are destined to die of breast cancer will still die of breast cancer — even if they get high-quality mammograms.”
Women contemplating whether to get a mammogram need to understand two things, says Fran Visco, president of the National Breast Cancer Coalition (and a breast cancer survivor): First, the deadliest cancers may spread before they’re detectable on even the best mammogram; second, some of the cancers that mammograms find will never harm you. Until we can distinguish harmless cancers from deadly ones, we’re compelled to treat all of them. Thus, some women get surgery, chemotherapy and other treatments for cancers that would never have hurt them, Visco says.
The decision to have a mammogram or not comes down to this: How much potential for harm will you accept in exchange for a chance that your life will be saved?
There are no absolute right answers, Visco says.
But here are some numbers to consider: According to an analysis published this month in JAMA Internal Medicine, for every 1,000 women age 40 who get an annual mammogram for 10 years, there will be 510 to 690 callbacks for something that isn’t cancer, 60 to 80 biopsies that don’t show a cancer, up to 11 women treated for a cancer that would not have killed them and fewer than two women whose lives are saved. From age 50 to 59 the figures are 490 to 670 callbacks, 10 to 100 unneeded biopsies, between three and 14 women unnecessarily treated for cancer, and fewer than four lives saved per 1,000 women. From age 60 to 69: 390 to 540 callbacks, 50 to 70 unneeded biopsies, between six and 20 women uselessly treated for cancer, and up to 49 lives saved.
“If you weigh the benefits and harms and decide to have a mammogram, that’s fine,” Visco says. “And if you make a decision not to, that’s fine, too. You don’t have to feel compelled.”
To confuse matters further, two large studies have shown that monthly breast self-exams increase the number of suspicious lumps that are found, but do not reduce cancer deaths. The American Cancer Society updated its guidelines in 2006, stating that these exams are optional except for women who are at high risk for the disease.
The solution is not to stop looking for breast cancers, but to look more strategically, says Susan Love, a breast surgeon, activist and director of the Dr. Susan Love Research Foundation. The U.S. Preventive Services Task Force recommends mammograms every other year for women 50 to 74 because such an interval offers similar benefits as an annual screening with less risk of false positives or unnecessary diagnoses.
The “breast awareness” approach to self-exams also seeks to balance the benefits of looking against the downsides of hyper-vigilance. Pay attention to your body, but don’t obsess, Love says. “We need to stop thinking about our breasts as hidden time bombs that are going to do us in at any moment,” she says. Many women find their own breast cancer, but they usually discover it when they’re rolling over in bed, getting dressed or making love, not while performing a monthly self-exam, Love says. If you find something, get it checked out.
Your chances of being helped by a mammogram are greatest in your 60s, while your likelihood of getting a biopsy you didn’t need increases the earlier you start mammography. Half of all women who start annual mammograms in their 40s will have a false-positive result, and Michael LeFevre, co-chair of the task force, worries that this can lead to screening fatigue. By the time they get to their 60s, he says, they’ve had enough — just as they arrive at the age where the benefits of mammography are greatest. He encourages women to discuss their concerns with their doctors so they can make decisions based on their individual risk factors and values.