In Japan, mass screening for breast cancer in women employs physical breast examination, although its efficacy seems not to be adequate. The Ministry of Health and Welfare of the Japanese Government is considering the introduction of mammography for mass screening. However, there is a general fear among the public about the risk of radiation exposure by mammography, especially in Japanese women.
A study was therefore conducted to compare quantitatively the risk of mammography exposure and the benefit of mass screening for breast cancer, and to clarify the age of women above which mammographic screening may be justified. The absorbed dose of radiation produced by screening mammography is assumed to be 0.6 cGy at maximum and 0.2 cGy on average for two-view mammography. The benefit of mass screening for breast cancer is estimated in terms of life-years saved from breast cancer based on the incidence rate among average Japanese women, and the risk of exposure is calculated in terms of loss of years due to radiation-induced breast cancer. The risk and benefit were found to be equal at the age of 30 years, and benefit was found to exceed the risk in women over 30 years of age. In conclusion, mammographic screening seems justified for Japanese women aged 40 years or over, provided that quality control of the radiation dose is established in order to limit the maximum dose to 0.6 cGy.

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Five hundred and thirty-seven breast cancer patients were entered for a registry program in Fukui prefecture between 1984 and 1987. The overall 5-year survival rate was 79.5%. The rates decreased with age ; 82.9% in the group aged 54 years and under, 79.4% in the 55-69 year-old group, and 68.8% in the group aged 70 years and over. Patients with an occupation showed better survival than those without, such as housewives, 86.7% and 75.7% respectively. Living area made a difference to the rate : 81.3% in city dwellers and 75.5% in town & village dwellers.
Analysis of these disparities in survival rate revealed the following :
1) Within groups showing lower survival, such as the older group, group without occupation and group living in a town & village, the incidence of more advanced disease was much higher than in the opposite group for each category. This might have been due to delay in becoming aware of subjective symptoms in the former groups.
2) The latter two groups showed a tendency to postpone consulting a physician, which might also have produced the lower survival rates.
3) Multivariate analysis of these 3 social factors revealed that engagement in an occupation had the most powerful influence on survival.
It is stressed that not only biological, but also social influences must be taken into consideration in mass-screening and educational projects to improve cancer patient survival.

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Today, steps to increase the number of women taking medical check-ups and to popularize self-examination of the breast are regarded as important for early detection of breast cancer. At our center, since its establishment in 1991, we have encouraged women attending for physical check-ups to carry out breast self-examination (BSE) as part of a regular health-testing program for detection of adult diseases.
In this study, we investigated the outcome of our guidance program to determine its effectiveness, women's comprehension of BSE, and their acquisition of regular testing through oral telephone questioning. It was found that the rate of conducting BSE had increased, but that women's understanding of BSE manuals was insufficient. The reasons why BSE was not done included “too busy to remember”, or “confidence after receiving an all-clear at the previous check-up”. Thus it was clear that women lacked knowledge about breast cancer. Judging from the above findings, verbal guidance seems inadequate for widespread understanding because of learning gaps among individuals. Through this experience, as of April 1993, we have been conducting BSE training on an individual basis. Through these procedures we are able to learn of practical problems among examinees (e.g. women wearing special clothes for screening in both the sitting and supine position) so that we can provide a more personal approach, improve the BSE ratio, and help women learn the right BSE technique.

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