This is an interim report by a team studying the appropriateness and effectiveness of breast cancer screening for reducing mortality in women aged under 50. The Miyagi Trial showed that the breast cancer detection rate for women in their 40's was higher by mammography (0.15%) than by inspection and palpation (0.11%), and was also higher in women aged 50-69 years (0.09% and 0.13 %). The detection rate by mammographic screening was 0.20% in both age groups, suggesting that mammographic screening might be effective for women in their 40's. Mammograms of women younger than 50 revealed a greater degree of heterogeneity and high breast density than those of women over 50 (85% and 64%, respectively). The optical density set of the breast by the automatic exposure control (AEC) system, changing from 1.25 to 1.50, was reduced in the high density group.
That pointed out the importance of quality control of the mammography. Ultrasonic screening, including the methods, apparatus, and criteria necessary for a thorough examination, was varied by the technician in charge. Studies are now being conducted on the criteria for thorough examination and training methods. We also made a comparison between the cost and effectiveness of cancer screening by mammography and ultrasonography. It was found that the cost of extending one-year survival in women aged between 40 and 49 was ¥ 1, 092, 000 for mammographic screening, ¥ 1, 872, 000 for ultrasonic screening, and ¥ 1, 457, 000 for screening by inspection and palpation.Therefore, mammographic screening was least expensive, and ultrasonic screening was the most expensive. However, it will be necessary to collect more data for ultrasonic screening.

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We conducted a study to determine whether biennial mammography was the optimal screening interval for women aged 40-49.
From 1996 to 2000 in Miyagi prefecture, we performed annual or biennial breast cancer screening using clinical breast examination combined with or without single-view mammography. The past records and the stages of the detected cancers for 87 screenees aged 40-49 and 117 screenees aged 50-69, were investigated.
There were 25 screenees aged 40-49 in whom cancers were detected by clinical breast examination combined with mammography, and 117 aged 50-69. Rates of early breast cancer in screenees aged 40-49 for annual and biennial repeat mammography were both 100% (2 and 3 cases respectively) and those in screenees aged 50-69 were 88% and 77% (8 and 13 cases, respectively). Four screenees aged 40-49 and 6 aged 50-69 in whom cancer was detected by clinical breast examination alone had been negative by mammographic screening one year before. Assuming that these cases and interval cancers were false negative, the sensitivities for screening by clinical breast examination combined with mammography for women aged 40-49 and those aged 50-69 were 81% and 90%, respectively. The relative parenchymal density of all false negative screenees aged 40-49 was 50% and over.
It is suggested that biennial screening for women aged 40 to 49 is unsuitable. Annual clinical breast examination combined with biennial mammography or choice of optimum modality according to individual breast density may be necessary for women in this age group.

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Mammographic screening for breast cancer was performed in Tokushima prefecture from 1995 to 2000. Of 17, 956 screenees examined, 53 were diagnosed as having breast cancer (recall rate 6.8%). The detection rate and sensitivity in all women and in those aged 50 and over were significantly different from those for physical examination alone. The detection rate and sensivitity in women aged 49 and under were 0.19% and 84.6%, respectively. These results were better than those for physical examination alone, although the difference was not significant. All the breast cancers detected in those aged 49 and under were early cancers.
These results suggest that mammographic screening may be effective for women aged 49 and under in Japan.

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In order to consider the introduction of mammography for breast cancer screening in women aged under 50, we compared the findings on diagnostic mammograms in women aged 40-49 with those in women aged 50 or over.
Methods : From July to December 1998, 1, 777 patients underwent diagnostic mammography in our outpatient clinic. We investigated these mammography reports regarding the findings, the assessment categories, and the outcomes.
Results : Proportion of the dense breast in women aged 40-49 and those aged 50 or over was 27 % and 12%, the positive predictive value was 28% and 44%, and the false negative rate was 8.5% and 4.7%, respectively. There are 8 patients with breast cancer whose mammogram could not show any abnormalities. The pattern of small nodule (T1 tumor) in extremely dense breast tissue were observed in 5 of these false negative patients.
Conclusion : Although the positive predictive value for women aged 40-49 was lower than the value for women aged 50 or over because of the difference in parenchymal density, the sensitivity for women aged 40-49 held 90% or more. We can expect the effectiveness of mammographic mass-screening for breast cancer in women aged 40-49.

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In Kagoshima prefecture, a program of mammographic mass screening for breast cancer by bus was started in April 2000. Women over 40 years old were examined by mammography together with physical examination. We made a comparative study of two groups of women aged 40-49 years and over 50 years, and found a difference in the rate of further examination. However, there was no difference in diagnostic accuracy or the rate of cancer detected. Similarly, there was no difference in the rate of early breast cancer detected.
In conclusion, mass screening by mammography is likely to be more beneficial for women aged 40-49 years that for women aged 50 years and over.

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We evaluated the role of mammography (MMG) and ultrasound (US) in diagnosis and screening of early breast cancer in 197 cases (41 non-palpable (Tnp), 156 less than 2 cm in diameter (T1)). The patients ranged in age from 40 to 49 yr, and underwent surgery at the Cancer Institute Hospital between 1997 and 1999. The total detection rate, including close examination, was higher for US (92%) than for MMG (85%), but in Tnp cases the rate was higher for MMG (78%) than for US (63%). Among these 197 cases, screening MMG was performed in 39 cases, and screening US was performed in 32. In these “screening” cases, the detection rate for screening MMG (64%) was almost the same as that for screening US (66%). In Tnp cases the detection rate for screening MMG (77%) was higher than that for screening US (44%), whereas in Ti cases the detection rate for screening US (88%) was higher than that for screening MMG (47%). Eleven cases were detected only by screening US, among which 55% were T1 and 88% were invasive cancer. Ten cases were detected only by screening MMG, among which 90% were Tnp and 80% were DCIS (with calcification seen by MMG). When adopting MMG or US for breast screening, we need to consider the accuracy of palpation and the aim of the screening (i.e. whether the priority is non-palpable cancer or small mass, DCIS or small invasive cancer).

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The significance of breast cancer screening by mammography (MMG) and ultrasound (US) for women aged 49 and under was studied on the basis of data obtained from our ten years of experience with a system for super-early diagnosis of breast cancer using a combination of physical examination, MMG and US applied to all first visits and annual follow-up patients. Seven percent of breast cancer lesions were not imaged by MMG, of which 72% of the patients were 49 years old or less. All these lesions, excluding lesions causing bloody nipple discharge (BND) without masses, were clearly seen by US. All non-palpable breast cancer lesions, excluding BND cases, were visualized by either MMG or US. US alone showed images in 28% of cases. By adding US to MMG for screening, 46% more non-palpable breast cancers were estimated to be detectable by screening. Our study of breast cancer lesions with a maximal length of 10 mm or less showed one or more US findings indicative of malignancy in 90% of cases, suggesting that it would be relatively easy to detect such small breast cancer lesions by careful US scanning. Breast cancer lesions which had been detected but misdiagnosed as benign upon initial examination and then followed up accounted for 4.6% of all breast cancer cases. It was found that application of core-needle biopsy instead of fine-needle aspiration cytology could reduce the frequency of such misdiagnosis.
This study was based on data obtained from the outpatients' records. As a consequence, in April 2001, we started a mobile van service for breast cancer screening utilizing MMG with computer aided diagnosis, US and instruction in breast self-examination, and we hope to analyze the data from all screened cases in a future study.

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Subsequent to the fourth report, 12 mammogram training courses were held in 2001. Among them, 5 courses were ranked α, 4 as β, and 3 as γ. Only 5 courses (42% of the total including 3α, and 2 β) satisfied the requirements for film reading tests as outlined in the second report. As a group, the test results were worse than those of the 11 courses examined in the third report, suggesting that training course planning and management need to be restructured. Since 2001, questionnaires have been computerized to speed collation and analysis of results and provide immediate feedback to the instructors. The instructors and assistant instructors participating in the lectures and workshops were also given questionnaires at 22 courses to determine whether improvement of instructor competence is important for control of course quality. The results obtained are reported here. There were a total of 182 instructors and 117 assistant instructors, of whom 89 (49 %) and 72 (62%) answered the questionnaire, respectively. Thirty-six percent of the instructors and 56% of the assistant instructors indicated that preliminary meetings for the workshops were inadequate or not held. Only 20% of the assistant instructors felt they were sufficiently competent. To raise the level of the workshops, it appears that assistant instructors, who have less teaching experience than instructors, need more preparation. Preliminary meetings, prompt analysis of the questionnaires with immediate on-site feedback to the instructors, and review meetings, some of which have been implemented at recent courses, are necessary to maintain the proficiency of instructors and assistant instructors.

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In addition to palpation, screening of breast cancer is performed by mammography and ultrasonography at our facility. We studied women who were found to have single, unilateral breast cancers between 1996 and 2000. They were classified into three groups 'interval breast cancer', 'breast cancer diagnosed by periodic screening', and 'breast cancer diagnosed in the outpatient department' and studied clinicopathologically. There were no significant differences in age, body mass index, menopausal status, or age at first parturition among the three groups. The proportion of nonpalpable breast cancers in the 'breast cancer diagnosed by periodic screening' group was significantly (p<0.01) higher than in other groups. There was significantly (p<0.05) more women with 'familial history in the interval breast cancer' group than in the other groups. Symptoms appeared sooner in women who had interval breast cancer without a familial history. With regard to pathological findings, scirrhous carcinoma appeared in a signicantly (p<0.01) greater proportion of women in the 'breast cancer diagnosed by periodic screening' group than in the other groups. The mean of distance of tumor in the 'breast cancer diagnosed by periodic screening' group was significantly (p=0.05) smaller than in the 'breast cancer diagnosed in the outpatient clinic' group (p=0.05). In future, screening for breast cancer needs to focus on three issues : more detailed investigation of patients in whom breast cancer is overlooked, modality-preferably ultrasonography, and recommendation for annual screening.

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