The quality of mass screening for breast cancer by physical examination

Mass screening for breast cancer using physical examination alone has been carried out since 1983 in Zentsuji, Kagawa Prefecture, Japan. Over a 7-year period, breast cancer was detected in 11 of a total 8,271 examinees, the detection rate being high at 0.13%. The detected cases included a few early-staged breast cancers, suggesting that mass screenings are of slight efficacy. Seven cases of interval cancer were found by breast self-examination after the mass screenings, supporting the value of breast self-examination. A relatively large number of interval breast cancers was detected in 1985 and 1986, when the rates of required further examination remained under 1%. The sensitivity and specificity of this screening were 61.1% and 94.5%, respectively, indicating a low sensitivity. These results suggest that the qualitative diagnoses made from the first screening by physical examination alone were often revealed to be false negatives. Therefore, the existing diagnosis should be employed in the first screenings. It is recommended that mammography be introduced to detect breast tumors which are nonpalpable or undetectable by physical examination alone.