Two systems of mammographic screening for breast cancer are performed in Tokushima Prefecture. Under one system each woman undergoes a physical examination and mammography simultaneously (simultaneous examinations), whereas under the other system each woman undergoes a physical examination and mammography separately on the same day (consecutive examinations).
Between 1991 and 1998 6, 991 women underwent the simultaneous examinations and 4, 156 underwent the consecutive examinations. The recall rates were 7.9% and 9.3%, respectively. These data suggest that simultaneous physical examination + mammography is a suitable screening procedure.

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With the aim of introducing screening mammography in Japan, we have investigated the number of mammographic apparatuses, photographers and interpreting physicians using mailed questionnaires. The questionnaires were distributed to 2, 380 facilities and the members of breast cancer screening-related medical societies including the Japan Association of Breast Cancer Screening, the Japan Breast Cancer Society and the Japan Radiological Society (JRS). Sixty-seven percent of the facilities intended to utilize mammography for breast cancer screening. However, only 42% of the facilities had mammography facilities that were accredited by the JRS. The film sensitivity was increased 1.72.5-fold as compared with the conventional Min-R/Min-R system, indicating that the radiation risk would be markedly decreased. In 827 hospitals, photographers were engaged in mammography. A total of 2, 576 physicians stated that they would be happy to interpret mammograms if screening mammography could be conducted. An educational system should be programmed to ensure quality control for photographers and interpreting physicians.

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In Japan, a new type of mass screening for breast cancer has been proposed by the Japan Association of Breast Cancer Screening-mammography performed together with a physical examination every 2-years for women over the age of 50. We are now performing breast cancer screening by physical examination alone, but a recent study showed that the present method is not reducing the mortality rate of breast cancer.
We have analyzed the cost-effectiveness of three mass screening programs for breast cancer : (1) physical examination alone, 1-year interval ; (2) mammography + physical examination, 1-year interval ; and (3) mammography + physical examination, 2-year interval. The analysis was performed using a mathematical model that we reported previously. The number life-years of women saved from breast cancer was used as a measure of effectiveness and costs included those of the screening test, of detailed examinations and of therapy. Various parameters utilized in our model were estimated based on the opinions of experts in the breast cancer research group headed by Dr. Ohuchi (Tohoku University, School of Medicine). The cost-effectiveness ratios are presented in terms of Yen/life-year saved and Yen/quality-adjusted life year saved. The latter ratio takes into consideration the benefits of breast conservation therapy, which results in a higher quality of life than mastectomy. We found that physical examination + mammography with a 2-year interval was the most cost-effective program followed by physical examination + mammography, with a 1-year interval. Physical examination, alone with a 1-year interval was the least cost-effective approach.
Consequently we conclude that performing mammography with a physical examination every 2 years is the method of choice among these three screening programs. However, further investigations should be carried out using more accurate parameters.

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In rural areas, general mass screening including internal medicine, breast cancer, lung cancer, gastric cancer, cervical cancer, and colon cancer is very effective, because there are few specialists for each cancer, and all examinations can be done on the same day. In urban areas, individual breast screening is very effective, because there are many specialists and it can be done on any day according to individual circumstances. We performed general mass screening in six towns, where the cover rate of breast screening in 1996 was 30.5%. This was significantly higher than in other areas of Kyoto prefecture (6.8%). Personal expenditure for screening in a town was decreased by about one third by changing the method from separate mass screening to general mass screening. This was because the number of staff on one day tripled, whereas the number of days taken for the screening decreased to one fifth. From 1996, we performed individual breast screening in the Uji area, which includes two cities and one town. In this area, the cover rate of breast screening increased from 8.6% to 10.3%, and the breast cancer detection rate increased from 0.14% to 0.23%.

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In 1998 mass screening for breast cancer was excluded from the Elderly Health Law by the Ministry of Welfare. As a result the financial burden is expected to increase on cities, towns and villages. We are afraid that this change will lead to a reduction in, or the abolition of, mass screening for breast cancer. To avoid this situation we should encourage local communities to continue mass screening by offering a screening test that is affordable and of higher accuracy than all previous tests. Therefore, we are proposing a new Group Mass Screening Format with three steps : (1) gather a large number of women in one place, (2) have them perform accurate self?examination, and (3) provide an examination by a physician only to those women who complain of abnormalities or have a large number of risk factors.
Women with abnormal findings would undergo further examinations by mammography and ultrasonography. Implementing this format will require educating the general population about breast cancer and training the women in “the accurate breast self-examination”.
An additional benefit of the proposed Group Mass Screening Format is that we will be able to introduce mammography for mass screening because of the low cost of this format.

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It has been reported that diagnostic computer systems can interpret the microcalcifications seen on mammograms with high sensitivity. We examined 441 women for breast cancer by mammography (medio-lateral-oblique and cranio-caudal images) and by whole-breast ultrasonography. The mammograms were then analyzed using a computer-aided diagnosis (CAD) system (ImageChecker M 1000 system ; R 2 Technology, Los Altos, CA, USA). After performing the CAD analysis we used the mammography findings mainly in the evaluation of microcalcifications and the ultrasound findings were used mainly in the assessment of any mass observed in the breasts.
The CAD system interpreted the microcalcifications with total accuracy. We diagnosed two patients with breast cancer, and cancer with microcalcifications was correctly identified by the CAD system. When CAD improves and the false-positive rate decreases this system will help the mammogram reader to assess many screening films. Therefore, this technology will reduce the cost of breast cancer screening.

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Since 1988 we have performed mass screening for breast cancer of women who attended hospitals in Kumamoto city for a variety of medical complaints. The mass screening of 87, 230 women was carried out between 1988 and 1997 and a second examination was required for 4, 104 women (4.7%). Breast cancer was found in 273 women (0.31%), which was a much higher rate than that seen in the mass screening program for Kumamoto prefecture (0.04%) that adopted a home visit system. Two hundred and twenty-two (81.3%) of 273 patients showed stage I or II disease according to the TNM classification scale. This proportion of early-stage disease cases was lower than that seen in the home visit program (90.4%), but was higher than that seen in patients with breast cancer in the Second Department of Surgery, Kumamoto University Hospital (74.3%).
These results suggest that mass screening for breast cancer of women attending Kumamoto city hospitals included patients with breast cancer who had come to the hospital after finding a lump during a self-examination.

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We have used phantom images to develop a digital method for assessing mammogram quality because it is more objective than visual evaluation. Using this method we analyzed images gathered in a regional survey of mammogram quality.
When our digital method of image quality assessment is used in a quality control process it is necessary to set a predetermined path/fail level. To determine the appropriate level we compared our quantitative measurements with the results of visual evaluation, the standard method, of image quality using 42 images of American College of Radiology accredited phantoms. The images were digitized and the signal-to-noise ratios (SNR) of calcifications (C ; Cl for the largest specks and C3 for the largest third specks) and masses (M ; M1 for the largest mass and M 3 for the largest third mass) were measured. The visual evaluations were performed by 14 readers-9 with substantial experience (group A) and 5 less experience (group B) who scored the images according to the Guidelines of the Japanese Association of Breast Cancer Screening. For each image, the group B readers gave under score than the group A readers. However, both groups showed large variations in scoring. The scores for calcifications and masses by readers in group A were mostly accurate when the SNRs of the test objects were higher than specific values : 13 in C1, 7.0 in C3 and 6.0 in M1. On a relative performance scale those values correspond to 0.75, 0.80 and 0.70, respectively.
We conclude that visual scoring of mammogram quality, even by experienced readers, results in large discrepancies. On the other hand, the path/fail level of image quality can be determined without ambiguity by quantitative measurement and we tentatively set the level to 0.7 to 0.80 on the relative performance scale.

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In recent years, it has been pointed out that the efficiency of mass screening by palpation alone is inadequate. During a period of 12 years, between 1986 and 1997, we conducted breast cancer mass screening by a combination of physical examination and real-time whole-breast ultrasonography. A total of 50.378 women aged 30 years or older were examined ; the total number of detected breast cancer cases was 61 and the rate of breast cancer discovery was 0.121%. Of these 61 breast cancer cases 16 were TO (impalpable) breast cancers, which were not detected by palpation by the initial examiner nor by a second examiner. Three of the 16 TO cases were detected due to bloody nipple discharge and the other 13 cases were detected only by ultrasonographic detection of a low-echoic tumor of 10 mm diameter or smaller. Moreover, of these 16 TO case 3 (18.7%) were noninvasive carcinomas and the other 13 (81.3%) were invasive carcinomas. Therefore, we suggest that mass screening using ultrasonography can detect more breast cancers, and a higher proportion of invasive breast cancers, than mass screening using mammography.
The 13 TO cases that we detected based only on the ultrasound findings accounted for 21.3% of the total number of breast cancers that we detected and would have been overlooked had the mass screening involved only a physical examination. Similarly, 4 of the 13 TO cases (30.8%) were diagnosed as being within the normal limits used for mass screening by mammography and would have been over-looked even by mammography + physical examination screening. Although there were no cases with lymph node metastasis, 8 of the breast cancer cases (23.1%) showed invasion into the lymphatic system (ly₁-ly₂) and 4 (30.8%) showed invasion into the neighboring adipose tissue. Furthermore, the 11 cases (84.6% of the TO cases) that were detected based on the ultrasound findings alone were detected at repeated examinations and were detected, on average, at 3.5 times that seen for annual mass screening by palpation and ultrasonography. We conclude that to conduct significantly beneficial mass screening for breast cancer we must undertake annual mass screening programs using real-time whole-breast ultrasonography, for previous participants and also for firsttime participants.

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