Breast Cancer Screening: A Medical Audit of the Screening Mammography Performed at One Institution for 10 Years

摘要

Purpose Screening for breast cancer has constantly been increasing since the benefit of screening for breast cancers was established. The purpose of this study was to investigate the efficacy of annual breast cancer screening at one institution for 10 years by conducting a medical audit. Methods From March 1995 to July 2004, we performed 110,588 annual clinical examinations and mammographies on 58,024 women, who wanted to undergo breast cancer screening. Two hundred fourteen breast cancers were detected during screening, and one hundred sixty one of these patients were operated on. We then compared these results with the ideal rates for medical audits. Results Of the 110,588 cases that were screened, the recall rate for further examination was 12.1% (n=13,423). The biopsy rate was 1.01% (n=1,116). Two hundred fourteen breast cancers were detected for a detection rate of 0.19%. The percent of stage 0 cancer among all the cancer was 23.6%, stage I was 40.4%, stage IIa was 19.9%, stage IIb and IIIa were a combined 6.2%, stage IIIc was 3.1%, and stage IV was 0.6%. The positive predictive value (PPV) based on the abnormal findings on the screening examinations was 1.6% (PPV1). The PPV when a biopsy or surgical consultation was recommended was 15.1% (PPV2). The percent of tumor found as stage 0 or I was 64% (103/161). The tumor found as minimal cancer (stage 0 or tumor lesser than 1 cm) was 38.5% (62/161). There were 38 cases of axillary lymph node metastasis (23.6%). The number of cases of cancers found per 1,000 cases was 1.7. The prevalence of cancer found per 1,000 first examinations was 2.3. The incidental cancer found per 1,000 follow-up examinations was 1.2. The recall rate for further evaluation was 12.1%. These results were compatible with the ideal rates for medical audits, except for the recall rate, the PPV1, the PPV2, and the cancers found per 1,000 cases. Conclusion On the base of these results, breast cancer screening was properly performed in this institution. Breast cancer screening using a clinical examination and a mammography is effective for the early detection of breast cancer.