Breast cancer: Dense breasts may spell trouble for menopausal women

An extremely dense breast prior to and after menopause may double the risk of breast cancer, according to a Korean cohort study.

The retrospective, longitudinal study included women aged >30 years who had undergone breast mammography serially at baseline and postmenopause as part of their regular health check-ups at Samsung Medical Center. None of the participants had been diagnosed with breast cancer at baseline.

Researchers measured mammographic breast density using the American College of Radiology Breast Imaging Reporting and Data System. Over a median follow-up of 4.8 years or 18,615 person-years, 45 women were diagnosed with breast cancer.

Dense breasts were highly prevalent among women who were younger, underweight, had low parity, or using contraceptives.

Over a 4-year period after menopause, the cumulative incidence of breast cancer increased. Specifically, women who had consistently extremely dense breast had a significantly higher cumulative incidence of breast cancer compared with other groups (incidence rate, 375 vs 203 per 100,000 person-years; p<0.01).

The findings underscore that women with risk factors should receive mammography frequently, and if extremely dense breast is detected from premenopause to postmenopause, additional modalities of breast cancer screening should be considered.

Breast density is considered a potential intermediate phenotype in the molecular pathway of breast cancer. It quantifies the amount of radiopaque fibroglandular tissue in the breast that consists of epithelial tissue and stroma as opposed to surrounding fat tissue that appears radiolucent on mammography. [JAMA Netw Open 2021;4:e2122810]