In Japan, the rate of mammography screening for breast cancer is low at just over 20%, and the breast cancer mortality rate is increasing. This contrasts with the situation in Europe and the United States, where the rate of mammography screening is 70～80% and mortality due to breast cancer has been decreasing since the late 1980s. The difference in the rates of mammography screening between the West and Japan is considered attributable to breast cancer screening practices in Japan. This paper covers the history of breast cancer screening in Japan, starting with the establishment of the Japan Association for Breast Cancer Screening (JABCS) in February 1991, subsequent steps, and future directions. In Japan, there are still many challenges, such as improving the cancer screening rate, the transition from analog to digital mammography, soft copy diagnosis (diagnostic monitoring), ultrasound examination for dense breast tissue in women in their 40s, and diagnostic imaging advances for MRI. In 2010, the JABCS attained the status of a Nonprofit Organization (NPO), having been a voluntary organization previously. Furtherdevelopment of the JABCS is expected.

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To ascertain the current status of ultrasonography in mammographic (MG) screening at centers equipped for detailed examination and to clarify the related issues, a questionnaire was sent to 181 centers, exclusive of those providing only medical check-ups, recognized by the Central Committee for Quality Control of Mammographic Screening in 7 prefectures of Chubu District. Of the 99 centers that returned the questionnaire (response rate, 54.7%), 82 answered “yes” to the use of breast ultrasound in clinical practice, in which the actual state of breast ultrasonography was analyzed. Examinations were performed by doctors alone at 24 centers, doctors and non-doctors at 40, and non-doctors alone at 18. Examinations by doctors were performed in doctors' offices at 28 centers, in inspection rooms at 26 and both at 10, frequently as outpatient examinations in 51 centers (79.7%). The mean duration of examination was 9.8 min for the first examination of a symptomatic patient, 7.5 min for follow-up, 9.6 min for the first examination of an asymptomatic patient, and 7.6 min for follow-up. For non-doctors, the respective times were 16.7, 14.4, 14.7, and 14.2 min, respectively. Non-doctors performing examinations alone (87.9%) and with insufficient MG information (50.0%) took a longer time. Frequently, the image was read only by doctors (65.5%), employing static images (93.3%). Qualified specialist doctors and technologists accounted for 16.2%, and the rate of participation in training by the Japan Association of Breast and Thyroid Sonology (JABTS) was 24.7%. Basedon the present questionnaire, conditions of breast ultrasonography for mild MG abnormalities still appear to be inadequate.

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Mie Medical Network of Breast Cancer Screening, a NPO, was assigned the task of breast cancer screening in Mie prefecture in April, 2010. For breast cancer screening in Mie prefecture in 2009, a questionnaire survey was performed toward both consigner and consignee. Consigners were local public offices managing breast cancer screening for local inhabitants, and consignees were facilities offering breast cancer screening. The number of breast cancer screening was investigated toward all 29 of consigners in Mie prefecture. The questionnaire survey was conducted toward all 52 of the facilities possessing mammography systems (breast cancer screening being performed at 48 of them) in Mie prefecture in 2009. We investigated the predictive additional number of breast cancer screening and also investigated the requisite number of staff to achieve the predictive maximum number of breast cancer screening. As a result, the total number of breast cancer screenings was 93,525, and the participation rate was 7.5% which was calculated by reduction of continuator in Mie prefecture in 2009. The continuator accounted for over 30% of all breast cancer screenings. The predictive additional number was 126,950, this indicates that a possible participation rate of 75.2% after 2011. To achieve this high participation rate, active support is essential for short-handed facilities, and about 20% increase of medical staff is necessary. To achieve a participation rate of over 50% as a goal, new screenees should be recruited and breast cancer screening of every other year should be enlightened.

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For quality control of breast cancer screening, it is essential to maintain an adequate recall rate and positive predictive value. In Yokohama, we apply a unique secondary film reading system for mammography screening. All screening mammograms are checked by several physicians. After the first diagnosis, screening mammograms are gathered for a secondary film reading service. If the first diagnosis is consistent with the second one, the diagnosis is adopted as the final diagnosis. However, if the first diagnosis differs from the second one, the final diagnosis is made by conference of 4~5 physicians. We examined whether our system is effective for achieving an adequate recall rate and positive predictive value.Subjects and methods: Our secondary film reading service dealt with 21,553 cases in 2006, and 25,650 cases in 2007. Method A: The final diagnosis is defined as positive irrespective of whether the first or second diagnosis is positive. Method B (our present method): A positive diagnosis is made when the secondary film reading service committee arrives at a positive diagnosis. We compared the recall rates and positive predictive values for methods A and B.Results: The recall rates and positive predictive values for method A were 8.8% and 2.1% in 2006, and 8.8% and 2.6% in 2007, respectively. The corresponding values for method B were 5.5% and 3.2% in 2006, and 5.8% and 4.0% in 2007, respectively. Method B showed a significantly lower recall rate and a higher positive predictive value than method A.Conclusion: Our secondary reading method is effective for maintaining adequate quality of breast cancer screening.

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A 42-year-old woman was referred to us for detailed examination of a left breast tumor that had been detected by palpation and mammography during breast cancer screening in December, 2009. The patient had no relevant medical history, and there was no family history of breast cancer. Physical examination revealed a spherical tumor 4cm in diameter in the upper-outer quadrant of the left breast. It was mobile, elastic and relatively firm with a smooth surface. There were no palpable lymph nodes in the axilla. Mammography showed a lobulated, homogeneously dense tumor shadow, with a partly unclear borderline, on the basis of which the tumor was evaluated as Category 4 (suspicious abnormality). Ultrasonography demonstrated an irregularly outlined, non-homogeneous, generally hypoechoic tumor mass, with a hyperechoic zone in the anterior peripheral area, where minute calcifications were evident and the anterior tumor line was interrupted. These findings were interpreted to indicate the presence of infiltrating cancer. A core needle biopsy demonstrated no malignant features, and the diagnosis was suspected fibroadenoma. In order to make a definite diagnosis, an incisional biopsy was performed, and the final pathologic diagnosis was mastopathic-type fibroadenoma.

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We describe a 68-year-old woman in whom screening mammography detected a mass classified as category 3. There was neither a palpable mass nor nipple discharge in the bilateral breasts on physical examination. Ultrasound showed a simple cyst. Eighteen months later, the patient noted the lump in the same area. Ultrasound showed a simple cyst that had enlarged to 12×9mm. Aspiration cytology was performed, and this yielded fluid stained with old blood. Cytology revealed class 2, and the cyst subsequently disappeared. Thirty months later, imaging studies showed a cluster of three simple cysts in the same location.Thereafter, the shape of the cyst changed, and it became palpable. As cytology showed class 5，excisional biopsy of the cyst was performed, and a diagnosis of ductal carcinoma in situ was established. The patient underwent wide excision with sentinel lymph node biopsy and irradiation (50Gy). Since then, she has continued endocrine therapy and there has been neither recurrence nor distant metastasis for five years. Intracystic carcinoma is a rare disease, accounting for 0.5～2.0% of all breast cancers. On the other hand, cysts are commonly encountered at breast clinics. If the lesion is diagnosed as a simple cyst without any symptoms, it is generally followed up. Cysts should be examined accurately and treated adequately because of the likelihood of intracystic carcinoma within the lesions, although the present case was considered to be extremely rare.

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