Fatty Breasts and Palpable Lumps: Diagnostic Mammogram Alone May Be Sufficient to Exclude Cancer

To assess whether diagnostic mammogram alone is sufficient to identify breast cancer in women with a palpable lump and almost entirely fatty breast density.

All 2D full-field diagnostic mammograms performed in a large health system were retrospectively identified for patients assigned "almost entirely fatty" breast density from January 2014 through December 2018 who presented with a palpable lump and had at least 2 years of follow-up. Women were excluded if they had a history of breast cancer, ipsilateral surgery, or clinical suspicion of abscess. Other exclusions included axillary lumps, lumps located in the retroareolar or posterior one-third of the breast, and lumps in which the lump marker was visible in only 1 view. The investigators performed image-only review of the diagnostic mammogram, with blinding of the image reports and any ensuing outcomes. Subsequently, the associated US was assessed. Cancer outcomes were ascertained via linkage with the regional tumor registry.

A total of 1552 eligible women, mean age 58.7 years ± 13.4, with 1791 lumps, were identified. Of these, 1139 women (73%) had no mammographic correlate, and 86 women (6%) had cancers corresponding to their lump, with 1 cancer having no mammographic correlate. The risk of cancer with no mammographic correlate to the palpable lump was 0.1% (1/1139 ; 95% CI, 0.0-0.3).

Diagnostic mammography alone has very low risk of missed cancer and is sufficient for evaluation of palpable symptoms in most women with fatty breast density.