Breast cancer in women under 50: Most are not high risk.

Background: In 2009, the United States Preventive Services Task Force changed the recommended starting age for annual screening mammography from 40 to 50 for non-"high risk" women. In 2015, the American Cancer Society issued similar guidelines, with a starting age of 45. Our hypothesis is that most women diagnosed with breast cancer in this age group do not fall into a "high risk" category.

Methods: A retrospective review of women less than 50 years of age diagnosed with breast cancer in the Legacy Health Care System was performed for January 2013 through December 2015. Validated risk assessment models were used to quantify risk. High risk was defined as lifetime risk of breast cancer greater than 20%.

Results: 249 women were identified. Of these, 79 (32%) of women were high risk. 170 (68%) did not fall into the high risk category.

Conclusion: In our population, approximately two thirds of women with breast cancer under 50 are non-"high risk". We argue that women should receive annual mammograms starting at age 40, because low risk is not protective.