Effectiveness of Mass Screening Combined with Mammography for Breast Cancer

Since 1991, we have been conducting a mass screening program combined with mammography (hereafter referred to as MMG) for breast cancer at the time of primary examination. A total of 6, 001 women participated in the screening. Of these, 5, 175 (86.2%) underwent MMG-combined screening. For time-saving and cost reduction, only unilateral views were taken. Upon evaluating the MMG images according to age groups, judgement could be made without much difficulty for about 90% of women in their 50s. Only 6.3% required a further detailed examination. In the MMG-combined group, 11 women (0.21%) were found to have breast cancer, and the lesions were at an early stage in 54.5% of then. This confirmed that our diagnostic approach compared favorably with the conventional method of inspection and palpation. The detection rate was higher for women in their 50s (6 cases ; 0.39%) for women in their 40s (5 cases ; 0.19%). 80% of cancers were at an early stage in women in their 40s compared with 33.3% for women in their 50s. Two women with TO stage disease were in their 40s. For this reason, mammographic mass screening was considered useful for women aged 40 years or older, showing 90% sensitivity, 93.3% specificity, and a 3.1% predetection rate. In evaluating all the cases, we realized that the site of the tumor was not always within the mammographic range and also that some of the examinees had undergone mammography previously. This study demonstrated the necessity of evaluating the film-taking direction, the need for well trained technologists, and the need to establish a better system for comparing current films with previous ones more easily.