Mammograms may be worth risks for some in their 40s

New research suggests that starting breast cancer screening at age 40 might be worthwhile for some women who have a higher-than-average risk of the disease, for example because their mother had cancer.

Researchers and cancer groups don't all agree on when women should begin getting regular mammograms, or how often they should be screened.

According to the United States Preventive Services Task Force (USPSTF), a federally-funded panel, evidence supports screening average-risk women age 50 to 74 every other year - but women can decide with their doctors to start earlier based how they weigh screening's risks and benefits.

One in eight U.S. women will developed invasive breast cancer at some point, according to estimates, but less than a quarter of them will die from it.

Mammograms have been shown to help detect tumors early while they're easier to treat, but they also have their downsides. So-called false positives are common and can lead to anxiety, more-invasive testing and even unnecessary treatment, as can over-diagnosis - when women are treated for small, slow-growing cancers that never would have ended up causing any symptoms.

Risk Factors for Breast Cancer for Women Aged 40 to 49 Years A Systematic Review and Meta-analysis

Data Synthesis: Sixty-six studies provided data for estimates. Extremely dense breasts on mammography or first-degree relatives with breast cancer were associated with at least a 2-fold increase in risk for breast cancer. Prior breast biopsy, second-degree relatives with breast cancer, or heterogeneously dense breasts were associated with a 1.5- to 2.0-fold increased risk; current use of oral contraceptives, nulliparity, and age 30 years or older at first birth were associated with a 1.0- to 1.5-fold increased risk.

Limitations: Studies varied by measures, reference groups, and adjustment for confounders, which could bias combined estimates. Effects of multiple risk factors were not considered.

Conclusion: Extremely dense breasts and first-degree relatives with breast cancer were each associated with at least a 2-fold increase in risk for breast cancer in women aged 40 to 49 years. Identification of these risk factors may be useful for personalized mammography screening.

Heidi D. Nelson, MD, MPH;
Bernadette Zakher, MBBS;
Amy Cantor, MD, MPH;
Rongwei Fu, PhD;
Jessica Griffin, MS;
Ellen S. O'Meara, PhD;
Diana S.M. Buist, PhD, MPH;
Karla Kerlikowske, MD, MS;
Nicolien T. van Ravesteyn, MSc;
Amy Trentham-Dietz, PhD;
Jeanne S. Mandelblatt, MD, MPH; and
Diana L. Miglioretti, PhD