Related Experiment Video
Updated: Feb 15, 2026

Changes in Mammary Gland Morphology and Breast Cancer Risk in Rats
Published on: October 16, 2010
Breast cancer in women under 50: Most are not high risk
Thomas Sutton1, Phil Reilly2, Nathalie Johnson3
1Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA.
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.
Related Concept Videos
Relative Risk
Factors Affecting the Risk of Infection
The integrity and count of the white blood cells help the body resist pathogens and fight infection. When impaired, it reduces the body's resistance to pathogens. The acidic pH levels of the gastrointestinal, genitourinary tracts, and skin...
Drug Toxicity: Risk factors
Design Example: Analyzing Capacity Contours for Flood Risk Assessment
Cancer
What is Cancer?
Although people have known about cancer for centuries, it was only in 1761 that Giovanni Morgagni of Padua performed a detailed autopsy of...

