The contribution of the current mass screening examination involving inspection and palpation to the reduction of breast cancer death was studied. We investigated the relationship between standard mortality rates (SMRs) by cities, towns and villages and the proportions of the examinees undergoing mass examination among all relevant subjects.
In Kochi prefecture, mass screening examination for breast cancer was initiated in 1973, and the proportion of examinees who underwent the examination in 1993 accounted for 16.6% of all relevant subjects over 30 years of age (under the Health Service Law for the Aged, 21.6%). The proportions of examinees varied according to cities, towns and villages as follows : less than 15% in 12 cities, towns and villages, 15-25% in 25, and higher than 25% in 16. The SMR for breast cancer in Kochi prefecture decreased from 90-95 (national average : 100) at the start of mass examination to slightly less than 80. The number of cities, towns and villages with an SMR of less than 80 was six (50.0%) out of the 12 in which the proportion of the examinees was less than 15%. The number was increased, however, to 31 (75.6%) of the 41 cities, towns and villages in which the proportion of the examinees was 15% or higher.
These results suggest that mass screening examination for breast cancer by inspection and palpation performed in 15% or more of all relevant subjects, provides sufficient preventive effects against breast cancer death.

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Our system of screening for breast cancer ensures that all the women involved are examined by real-time ultrasonography (US). A total of 23, 235 women with an average age of 47 yr were examined by real-time whole breast scanning (WBS). Approximately 18 examinations per hour were carried out. Of the total women participating, 8, 540 (36%) were examined by MMG in addition to WBS. Later the same day, US-guided aspiration cytology was performed on any lesions that had been detected by WBS. Fifty-nine breast cancers were detected, among which 29 (49%) were non-palpable. The rate of detection was 0.25%, which was double that for palpation only. WBS detected 22 non-palpable breast cancers, whereas MMG detected 7. The 22 cancers detected by WBS included 16 small invasive carcinomas, in comparison with only one invasive carcinoma found among the 7 cancers detected by MMG. It is important to note that most non-palpable breast cancers do not demonstrate the classic characteristics of malignancy, but often appear as stains, irregular mottled areas, fat-like masses, or adenoma-like masses. We cannot diagnose small non-palpable breast cancers on the basis of US findings alone. Therefore it is important to perform US-guided aspiration cytology on every lesion, even those which are found to be virtually benign. It is generally thought that MMG is superior to US with regard to the detection of non-palpable breast cancer. However, the technology of US has developed considerably, and we consider that mass screening with real-time whole breast scanning has great potential.

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Because of the scattered medical facilities in Hokkaido and the region's vastness, it is often difficult for patients (especially those with breast diseases) to visit a medical center. Such geographical conditions make it economically difficult for patients in this area. Considering Hokkaido's regional peculiarity, mammography and aspiration cytology (usually secondary screening) are performed immediately after the primary screening.
As a result, during the past 15 years, 149 cases (0.15%) of breast cancer have been detected. The detection rate at initial screening was 0.24%, whereas that at subsequent screening was 0.10%. Interval cancer was found in eight cases. With regard to the detection rate of early lesions in cases of consecutive breast cancer, the rate for mass screening was higher than that for outpatients; 77.5% of cancers screen-detected in asymptomatic women were at an early stages.
The present system of mass screening in Hokkaido is discussed in terms of regional peculiarity and various problems associated with the screening program itself. In conclusion, on the basis of our experience, we consider that examinations utilizing diagnostic imaging methods such as mammography should be introduced to enhance the effectiveness of mass screening.

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To establish the most appropriate methods and interval for periodic examination for detecting breast cancer in an early state in women visiting an outpatient clinic, 58 breast cancer patients at Saitama Cancer Center having a screening history in the last 2 years were investigated. A total of 33 patients (56.9%) were diagnosed as having early breast cancer. The rate of diagnostic accuracy in these patients was 55.2% by clinical palpation, 67.4% by mammography (MG) and 83.3% by ultrasonography (US), respectively. Because of the difficulty in obtaining an accurate diagnosis at an early state, preoperative biopsy of breast tumors was done in a high proportion of patients. On the other hand, we evaluated the rate of detection of malignant changes for each diagnostic method (MG and US) from the patients examined by the same methods. In the findings of MG, 61.9% (within a one-year interval) and 90.9% (within a 2-year interval) of cases revealed malignant changes, and 50.0% (within a one-year interval) and 100% (within 2-year interval) of cases showed malignant findings by US. On the basis of these results, we consider that annual screening using MG as well as US in addition to physical palpation might be valuable for obtaining early detection of breast cancer by periodic examination.

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Two trials of mass screening for breast cancer using mammography were carried out in Tokushima prefecture. In half of the mammographic examinations, breast cancer was detected as a mass shadow. This finding suggests that detection of a mass shadows is important for breast cancer screening using mammography. In addition, we examined the detection rate of breast cancer according to age and the mammographic parenchymal pattern according to age, and on the basis of our results, we considered mass screening using mammography to be suitable for asymptomatic women aged 50 years or more in Japan.

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[in Japanese]

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[in Japanese]

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Since January 1981, mass screening for breast cancer has been carried out in Nagano Prefecture. The methods used for initial examination were the inspection-palpation procedures adopted by the members of the Local Society of Medical Practitioners and ultrasonography. In October 1983, Nagano Cancer Center was opened as a center where closer examination for cancer detection could be performed.
Over the past 10 years and 3 months, 1, 441 women recommended to undergo closer examination after the first examination, have visited our breast clinic. These women were divided into two groups : those who visited between October 1983 and December 1988, and those who visited between January 1989 and December 1993.
The diagnostic ability of the examining doctors and the authors using physical examination and ultrasonography was compared among the two groups. Furthermore, popularization of breast self-examination (BSE) among examinees was investigated, and the following results were obtained.
1) Thirty (4.6%) of 655 women in the former group were found to have breast cancer, compared with 31 (3.9%) of 786 women in the latter group.
2) The diagnostic ability of the examining doctors based on physical and ultrasonic examination in the latter group was markedly higher than that in the former group.
3) The diagnostic ability of the authors based on physical and ultrasonic examination showed little difference between the groups.
4) It was considered that the above findings demonstrated a part of a merit to perform breast cancer mass screening.
5) The proportion of visitors understanding BSE was shown to increase gradually as the extent of mass screening increased. However, the proportion of women practising BSE was nearly 60% without fluctuations.
6) It is insufficient for BSE education to be given only at the time of first examination, and a new BSE counterplan should be adopted widely for women who do not receive mass screening.

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