Cancer risks: Breast density score is a number from 1 to 4

Breast density would be included in a mammography report under a bill proposed in the California Senate. What that would mean for women is receiving a score of 1 to 4 to help her and her doctor better assess her individual risk of developing breast cancer.

The risk of breast cancer is based on several factors: age, family history, previous breast biopsies, gene mutations and density. Having high-density tissue, which has less fat, raises breast-cancer risk; low-density tissue lowers it. Very dense breast tissue is harder to read on a mammogram.

The rating scale of 1 to 4 is in order of increasing density. So a score of 3 or 4 would signal a higher risk of developing breast cancer. The scale is from the American College of Radiology Breast Imaging Reporting and Data Systems criteria.

Breast density has nothing to do with breast size, experts caution. In addition, women should know that breast density tends to change over time -- with breasts often becoming less dense after menopause. According to the National Cancer Institute, two separate breast-density scores are likely to give a woman a better idea of her individual risk.

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