Sensitivity of mammography and physical examination of the breast for detecting breast cancer.

Mammography and physical examination of the breast are evaluated as screening instruments for detecting breast cancer based on local biopsy data obtained from women enrolled in a national breast cancer screening program. One hundren thirteen cancers (15.5%) of women who underwent biopsy) were detected. The individual sensitivities of mammography and physical examination for detecting breast cancer are 62% and 24%, respectively. The sensitivity of the two methods combined is 75% (85 of 113). Thirty-seven cancers were in situ or minimally invasive (less than or equal to 1 cm in greatest dimension). Eighty-one percent (30 of 37) of these small cancers were detected by screening, and they comprised 35% (30 of 85) of all cancers detected by mammography, physical examination, or both. Improved survival is anticipated due to this high rate of discovery of small cancers.