We have been conducting mass screening tests for breast cancer using physical examination combined with ultrasonic examination in Tochigi prefecture since 1987. In this article we describe the system and discuss the efficacy of ultrasonic examination using a still image recording system, which was begun in 1992.
This system involves examination by physicians, followed by ultrasonic examination, which laboratory technicians perform by request based on the result of the physical examination. The ultrasonic image, input to a digital optical-magnet disk, is then forwarded to specialists for interpretation. Persons requiring a more detailed examination are then picked out.
The number of persons investigated over the last six years has been 105, 845. Seventy subjects with breast cancer were found, giving a ratio of 0.07%. The ratio of individuals requiring more detailed examination was as low as 2.1% on average, due to the “squeezing” effect of the ultrasonic examination ; the figure was 1.7% in 1993. Moreover, the ratio of early-stage breast cancer was 46.4% among all cases it was as high as 73.3% for consecutive follow-up on a yearly basis.
The receiver-operating characteristic (ROC) curve for this system was obtained using the results of diagnostic ultrasonography and a questionnaire for more detailed examination. The curve characteristic was good and it was suggested by a further downward shift in the ratio of those requiring more detailed examination that relatively good examination sensitivity was maintained.
It was shown that this screening system, combining physical examination for the presence of a mass with ultrasonic examination for qualitative diagnosis, was efficacious in spite of the relatively small facility and the number of staff.

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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.

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We conducted a program of simultaneous mass screening for breast, thyroid and uterine cervical cancer. Of 444, 176 participants in this screening, 310 (0.07%) patients with breast cancer and 311 patients with thyroid cancer were found. Among 628, 575 participants, 709 (0.07%) with uterine cervical cancer and 37 (0.005%) with endometrial cancer were detected. Significantly more patients with early breast cancer (Tis, Stage I) were found by mass screening (46%) than among outpatients (N =925, 29%). Thyroid cancer with a maximum diameter of 2.0 cm or less was detected more frequently by mass screening (58%) than among outpatients (29%). Sixty three percent of patients with uterine cervical cancer had in situ carcinoma. The incidence of tracheal or recurrent nerve invasion was lower among mass screening patients than among outpatients. Simultaneous mass screening for breast, thyroid and uterine cancer is useful because of its low cost and effectiveness for detecting patients with early-stage cancer.

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Of registered cases of breast cancer, 92.4% were detected by self-recognition of symptoms. Housewives and aged women living in the country might have a tendency for delay in becoming aware of subjective symptoms, resulting in poorer survival rates. The present screening system has reduced the stage at defection, but has not produced satisfactory results in terms of survival rate on the whole. The most important problems in the present screening were suggested to be the low cover rate or its underuse, accounting for less than 15% of the objective population, and the fact that only physical examination is used.
Proposals for higher efficacy in this situation include : 1) Focusing on relevant objectives, namely, low-survival groups, particularly housewives. As to the age range covered, 30s is not recommended due to the lower cancer incidence rate, and the over-70s also seem to be doubtful because of the many other causes of death. 2) More widespread recall for complete examination : Analysis of the previous screening suggested that physical examination was less sensitive and produced a higher recall rate for women in their 40s, but that smaller tumors and non-palpable cases might be detected by a 10% recall rate. 3) Five-year survival rate of cases without node metastasis tended to become lower in the under-54-year group than in the 55-69-year group. The biological differences in carcinomas and the remaining life should be taken into consideration in the screening of premenopausal women.

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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. In our previous report, we have shown that the risk of radiation exposure by mammography is equal to the benefit of breast cancer screening at the age of 30 and becomes much smaller as the age of screenee increases.
This report describes the cost-effectiveness analysis of breast cancer screening when mammography is adopted together with physical examination as a screening method. A mathematical model was used to calculate the effectiveness of the screening in terms of person-years saved from breast cancer, the cost of the screening examination, and details of the examination as well as the therapeutic expenditure for screening-detected patients and outpatients. Finally, the cost-effectiveness ratio was estimated by dividing the cost of screening with person-year saved as a function of screenee age (Japanese women).
Various numerical data to be introduced into the mathematical model were obtained from a consensus panel of seven specialists in a research group on breast cancer screening under one of the authors (Dr. C. Kido).
The cost of one person-year saved depends greatly on the age of the screenee, but it is lowest at the age of 4549 years old, being 2.5×106 yen/person-year. However, this value is about 3times higher than those calculated for stomach and colorectal cancer screenings in Japan. Further investigation is needed to establish more accurate data for cost-effectiveness analysis using several model fields of breast cancer screening.

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I underwent training in breast cancer mass screening and mammography techniques in Finland from February 2nd to March 29th, 1994.
A nationwide mammography screening program was started in Finland in 1987. Screening covers women aged 50-59 years. Personal invitation letters are sent, and two-view (craniocaudal and medio-lateral oblique) screen-film mammography is performed as the only screening examination at two-year intervals.
The quality control of the mammography unit and imaging is guided by law and checked by the Medical Physicist at the Finnish Center fro Radiation and Nuclear Safety on an irregular basis, but at least once every 5 years.

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The Japanese College of Radiology sent me to Turku in Finland to attend and learn about a breast mass screening system by mammography in February and March 1994. Mass screening of breast cancer is performed by the Southwestern Finnish Cancer Society in Turku. The Finnish situation, the results of the screening, and my opinions regarding the mass screening of breast cancer are presented in this report. Breast cancer is the most important type of cancer in Finnish women, as with other European women. Finnish women are able to attend the first screening and also additional examinations, including cytology, free of charge if they are necessary. Since mass screening began in 1987, the attendance rate has remained at a high level, about 89% each year. The detection rate was 0.33% in 1992, and early cancer (Stage I) accounted for 78% of all breast cancers detected by the screening. The incidence of breast cancer in Finland is about twice that in Japan. There is a difference in the situation of breast cancer between Finland and Japan. However, Japan may eventually follow the Finnish example. That is, how to spread knowledge about breast cancer and screening, and to make a flexible schedule and comfortable situation for women who attend the screening. It is still very important but difficult to maintain a high level of quality and quantity for screening systems. In Finland, doctors and technologists are being trained every year, and the nation has a commitment to continue to use high-quality mammographic apparatus. If mass screening by any diagnostic imaging method is started in Japan, we should obtain advanced guidance from other countries and establish a suitable Japanese system.

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