Serum CA15-3 levels of 41 pre-operative patients with breast tumor and 113post-operative patients with breast cancer were meassured by radioimmunoassay.The sensitivity and specificity were 20%

93.7%

and 71.2%

respectively. In 50patients with bone metastasis

the sensitivity was 78.0%. It appears that due to itslow sensitivity for early diagnosis

CA15-3 RIA has little use for screening in generalpopulation to detect primary breast cancer in early stage but is benefical fordetecting its metastasis and recurrence.