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

We sought to determine how breast cancers that occur within 1 year after a normal mammogram are discovered.

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.

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).

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.