Two studies out this week underscore just how much is still unknown about breast cancer and how difficult some decisions can be when it comes to dealing with your own individual risk. A study published yesterday in the Journal of the American Medical Association finds that a significant number of women ages 25 to 40 who had chest radiation for a childhood cancer aren't getting screening mammograms, even though they have up to a 20 percent chance of developing breast cancer by the time they're 45. The study found that only 23 percent of the young women who had previous radiation-treated cancers, like leukemia, lymphoma or a bone tumor, had gotten a screening mammogram in the past year; about 47 percent of this under-40 group had never had a mammogram at all. The American Cancer Society recommends yearly mammograms beginning at age 25 or eight years after treatment, whichever comes last.
It seems strange to me that these women (or their doctors) would be negligent enough to ignore a dire health risk. But the authors of the editorial that accompanied the study point out that "the standard mammogram in detecting preinvasive and invasive breast cancer is known to be relatively poor in young women due to the density of breast tissue in this age group." What's more, screening mammograms provide a small dose of radiation, and it's not known whether repeated small doses of radiation further increase the risk of breast cancer in women who've already received high doses of radiation.
An alternative option: breast-screening magnetic resonance imaging, which involves no radiation and is far better at detecting breast cancers in women with dense breast tissue. In addition to calling for mammograms, the ACS recently began recommending MRIs for women at high breast cancer risk, including those with BRCA gene mutations and previous chest radiation for cancer treatment. Still, women already treated with radiation who are concerned about the radiation from mammograms may want to talk to their doctors about whether they can skip the mammogram and have just the MRI.
This week's second relevant study may help breast cancer patients determine whether to have a preventive mastectomy on the other breast. Researchers from the University of Texas M.D. Anderson Cancer Center found three independent risk factors that help determine whether cancer is likely to spread to the second breast: (1) having more than one tumor in the original breast; (2) having a tumor that starts in the milk-producing lobes but spreads around the breast instead of forming one solid lump; (3) having a high score on the "Gail risk model," which takes into account age, race, age at first childbirth, and family history of breast cancer. The researchers hope their findings can help guide women and perhaps reassure many that they don't need to have the second breast removed just to be safe.