When a mammogram detects an abnormality, it may not be clear without a biopsy whether that finding is benign or malignant. Mammography also works less well in younger women because their breasts tend to be more dense, Dr. Tice said. There is also the possibility that screenings can detect very early cancers that may not progress to life-altering, or life-threatening, disease, said Dr. Laura Shepardson, head of the section of breast imaging at Cleveland Clinic; as a result, patients may undergo therapies that they potentially do not need.
The more often that women are screened, the more abnormalities that are found, Dr. Tice said. Some biopsies don’t indicate cancer, yet still create anxiety for patients — but many biopsies do find cancer, he said, which saves lives.
Dr. Shepardson said that the task force is advising mammograms every other year because it’s “saying that there’s a real risk of anxiety that’s undue, or of unnecessary biopsies.” But “the American College of Radiology doesn’t feel like that’s a risk or a harm. That’s being proactive,” she said.
How to reduce your overall risk
“You can do everything right and still, for reasons entirely out of one’s control, end up with cancer,” Dr. Comen said. Many of the factors that contribute to breast cancer risk, like genetics and a family history of cancer, aren’t modifiable; others are within a patient’s control, but not necessarily practical. For example, having a child before age 35 lowers the risk of breast cancer, as does breastfeeding, but a doctor would never recommend a woman have a child by a certain age to reduce cancer risk, said Avonne Connor, a cancer epidemiologist at Johns Hopkins Bloomberg School of Public Health.
But a few behaviors have been linked to a lower risk of breast cancer, doctors said.
Limit your alcohol consumption.
A mounting body of evidence has tied drinking to a higher risk of cancer in general — and potentially to breast cancer in particular, partly because alcohol can boost levels of estrogen in the body. That doesn’t mean you can never drink, but doctors urged caution: Dr. Comen recommended that women who want to reduce their breast cancer risk associated with alcohol have no more than three alcoholic drinks per week on average, and to be open and honest about their drinking habits with their doctors.