Survival rates for breast cancers detected in a community service screening mammogram program

Background This single-institution long-term prospective study was performed in the setting of community service screening mammography to evaluate the association between the methods of breast cancer detection and survival rates. Methods From 1994 through 2001, data on 1237 patients with breast cancer were collected concurrent with definitive surgical treatment and entered into a comprehensive database. Results Mammography was the sole method of detection for 517 (44%) of 1179 Tis-T2 breast cancers. Fifty-seven percent of invasive cancers detectable by mammography alone were less than 1 cm in diameter. For 1049 patients with invasive cancers, the 5-year overall observed survival rates were 94% for 372 whose cancers were detectable by mammogram alone and 87% for 677 whose cancers were detectable by palpation (alone or in combination with mammography) (P = .0002). Conclusions Most of the contribution to breast cancer mortality reduction is from the detection of small nonpalpable cancers, not from adjuvant therapy.