Discovery of breast cancers within 1 year of a normal screening mammogram: how are they found?

PURPOSE: We sought to determine how breast cancers that occur within 1 year after a normal mammogram are discovered.
METHODS: Using population-based mammography registry data from 2000-2002, we identified 143 women with interval breast cancers and 481 women with screen-detected breast cancers. We surveyed women's primary care clinicians to assess how the interval breast cancers were found and factors associated with their discovery.
RESULTS: Women with interval cancers were twice as likely to have a personal history of breast cancer (30.1%) as women with screen-detected cancers (13.6%). Among women with interval cancers, one half of the invasive tumors (49.5%) were discovered when women initiated a health care visit because of a breast concern, and 16.8% were discovered when a clinician found an area of concern while conducting a routine clinical breast examination. Having a lump and both a personal and a family history of breast cancer was the most common reason why women initiated a health care visit (44%) (P <.01).
CONCLUSIONS: Women with interval cancers are most likely to initiate a visit to a primary care clinician when they have 2 or more breast concerns. These concerns are most likely to include having a lump and a personal and/or family history of breast cancer. Women at highest risk for breast cancer may need closer surveillance by their primary care clinicians and may benefit from a strong educational message to come for a visit as soon as they find a lump.