Performance of opportunistic breast cancer screening in Slovenia

The purpose of the study was to assess performance indicators of opportunistic breast screening carried out in one of the Primary Breast Diseases Centers (PBDC) and to find out if these indicators meet the standards set in "European guidelines for quality assurance in mammographic screening". The records of 1,896 asymptomatic women, aged between 50 and 69 years who attended PBDC for the first time in the period from October 15 1998 to October 15 2002, were reviewed. In all of them, clinical examination and mammography was done. If necessary, non-invasive additional imaging was also performed in the PBDC. If malignancy could not be excluded, the women were referred to the Institute of Oncology (IO) for additional invasive diagnostic procedures. The data on these findings were collected from the records of the IO. We compared our results with the recommended values of performance indicators valid for organized screening programs as determined by "European guidelines". Of 1,896 women, 415 (22%) were recalled for additional imaging. In 335/415 women the suspicion for malignancy was excluded with noninvasive diagnostic methods. Invasive diagnostic procedures were applied in 80/415 women. Carcinomas were detected in 23 women, the majority of them (96%) were non palpable. All carcinomas were ductal; 9 (39%), 7 (30.5%), 7 (30.5%) were grade 1, 2 and 3, respectively. One carcinoma was preinvasive; 20 had the tumor size T1, 1 had T2, while in one the size was not specified. The axillary lymph nodes were negative in 14/23 (61%) women with invasive carcinoma and positive in 5/23 (22%). Surgery of the axilla was considered unnecessary in 4/23 (17%). Diagnostic sensitivity in presented cohort was 96%, specificity 79%. After a negative mammogram 1 interval cancer was detected. Compared to the "European guidelines" we achieved satisfactory results in the number and size of detected and interval cancers, but the analysis showed a higher recall rate with too many false-positive results. Efforts should target lowering the recall rate without reducing the cancer detection rate. Compared to Slovenian average, a large percentage of localized breast cancers in our study claim for organized breast cancer screening program in Slovenia at earliest convenience.