[Reference standards in the performance of a mammographic screening program. Results of the screening program in the province of Florence, 1992].

The authors report the results of the Florence District program for the year 1992. 11,033 subjects were examined. Attendance rate (64.4%) was significantly related to age (42-49 = 71.0%; 50-59 = 66.7%; 60-70 = 58.5%). Recall rate to diagnostic assessment was 2.09% (mammographic abnormalities = 199, subjective symptoms other than pain = 32) and was related to age (42-49 = 3.12%; 50-59 = 1.65%; 60-70 = 1.77%). According to the results of diagnostic assessment 53 surgical biopsies (0.48%) were recommended and performed. The biopsy rate was also related to age (42-49 = 0.2%; 50-59 = 0.4%; 60-70 = 0.7%). Forty-seven carcinomas were detected in 46 subjects (benign/malignant biopsy ratio = 0.13). Cancer detection rate was 0.42% and changed significantly with age (42-49 = 0.13; 50-59 = 0.36; 60-70 = 0.68%), as well as the observed/expected cancer ratio (42-49 = 0.89; 50-59 = 2.03; 60-70 = 2.98). Detected cancers were nonpalpable in 57% of cases. Pathologic staging was pTIS in 2 cases, pT1a in 5, pT1b in 17, pT1c in 17, pT2 in 5, and pT4b in one case. Six of 47 (12.8%) cancers involved axillary nodes. A preliminary estimate of screening cost yielded a total cost of Lit. 397,671,000 for the year 1992--i.e., Lit. 36,000 per examined subject and Lit. 8,461,000 per detected cancer. The results are compared with reference standards for the evaluation of screening performance provided by the national breast screening program in the United Kingdom.