Analysis of clinically occult and mammographically occult breast tumors.

Findings by xeromammography and clinical examination were compared in 16,000 self-selected women aged 45-64 who participated in a voluntary breast cancer screening program. A total of 138 malignancies were detected: 108 (78%) by mammography and 78 (57%) by clinical examination. Mammography was more effective for large breasts, fatty breasts, and in older women. Conversely, clinical examination was more effective for small breasts, dense breasts, and retroareolar lesions. Clinical detection decreased strikingly for lesions with negative lymph nodes, in situ and microinvasive lesions, deeply situated lesions, and lesions where microcalcifications were the sole mammographic finding.