The effect of mass screening for breast cancer: results of a multivariate analysis

Effectiveness of mass screening for breast cancer in Japan

BACKGROUND

Breast cancer screening has been conducted in Japan mainly by physical examination, the standard method for breast cancer screening according to the Law of Health Services for the Elderly. The purpose of this study was to evaluate the effectiveness of mass screening for breast cancer in Japan.

METHODS

We calculated the average coverage-rates for breast cancer screening per year from 1986 to 1995 for women aged 30-69 years for all of the 3255 municipalities in Japan, selecting "high coverage-rate" municipalities with average coverage-rates of 20%, 30%, 40% or more. Two municipalities were selected as "controls" for each high coverage-rate municipality, and were matched for population, National Health Insurance rate, and the age-adjusted death rate from cancer of the female breast in the period 1986-90. We compared the change in the age-adjusted death rate from 1986-90 to 1991-95 of the high coverage-rate municipalities and the comparable controls.

RESULTS

The percent reduction in the age-adjusted death rate from cancer of the breast in the high coverage-rate municipalities was statistically significantly greater than those in the controls.

CONCLUSIONS

The results suggest that mass screening for female breast cancer, mainly by physical examination, contributed to the reduction of mortality from breast cancer.

A Comparison of Mass Screening for Breast Cancer Using Mammography and Physical Examination Alone in Japan

To compare the sensivity of breast cancer screening methods by conventional physical examination and film mammography, a trial of mass screening for breast cancer using mammography was principally carried out in asymptomatic women over 50 years of age in Tokushima Prefecture. In this trial craniocaudal and mediolateral oblique imagings of the breast using two-view film mammography and physical examination, using inspection and palpation of the breasts were performed independently. Breast cancer was detected in 8 of a total of 950 examinees by mammography alone, and no cases of breast cancer were detected by physical examination. The detection rate of breast cancer was 0.84%, that is 7 times higher than that(0.12%) obtained by conventional mass screening using physical examination alone. The detection rate of increased especially in the sixth and seventh decades of life. The stage of the detected breast cancer was stage 0 (Tis) in 5 cases and stage T, with a tumor size of 1.0 cm or less, in 3 cases. All 8 cases were in the early stage, and they underwent breast conservation therapy. Based on these results, it is recommended to employ mammography in breast cancer screening for asymptomatic women aged over 50 years. We consider mammography alone may be sufficient for mass screening for breast cancer in these subjects.

Breast self-examination beliefs: a descriptive study

Breast cancer is a major cause of morbidity and mortality among American women. Evidence indicates that regular breast self-examination (BSE) may reduce breast cancer mortality by 18%, yet the majority of women do not practice it. This study used a decision model to examine the BSE-related characteristics, beliefs, and behaviors of 52 working women age 21 to 65 years (mean 44.05 yrs). Nearly 29% of the sample performed BSE. They were more likely than nonperformers to be white, to have a close relative who had breast cancer, and to believe that breast problems could be detected through BSE. Fears, particularly fear of cancer, were more likely to affect performers' than nonperformers' BSE decision. Nonperformers were more likely to think that the first symptom of breast cancer would be a sensation of some type, and that a healthy lifestyle protected them from the disease. They also were more likely to think reminders would encourage them to perform BSE. The most often reported sources of information about BSE were health care providers and friends or relatives.

Effect of mass screening for breast cancer from the aspect of psychosocial assessment of the quality of life

To assess the quality of life (QOL) in patients with breast cancer receiving mass screening, a collaborative matched case-control study was conducted in nine hospitals throughout Japan. A total of 122 patients detected by mass screening (study group) and 226 patients found in out-patient clinics (control group) were assessed psychosocially on the basis of questionnaire information. The incidence of patients with early stage breast cancer was significantly higher in the study group than in the control group (P < 0.05). Chest wall pain was observed in 35.2% of the study group and in 46.5% of the control group (P < 0.05). Although control patients were more optimistic than study group patients, disturbed daily life and anxiety about recurrence were a little more frequent in the former group than in the latter. In particular, shoulder stiffness was frequently seen in the control group (P < 0.05). Early detection and information do not create anxiety in mass screening patients (P < 0.01). We should recommend mass screening to patients to detect early stage breast cancer and provide better QOL.

Large-scale, population-based prospective studies in Japan

Large scale, population-based prospective studies have increasing importance for the study of common cancers in view of the possibility of advancing the understanding of different risk factors in the initiation, promotion and progression phases during what is thought to be the long process of human carcinogenesis. The permanent registration system in Japan ("Koseki") simplifies the follow-up of registered participants of such cohorts. The population-based cohort studied by Hirayama and the cohort of the atomic bomb survivors started during the 1960s are examples of such possibilities in Japan. Rapidly changing patterns of disease and lifestyles during the last 30 years require new population-based prospective studies focusing on a different set of exposures and with increased detail of exposure assessment. We have established a new population-based prospective study, the "Koseisho" cohort, between 1990 to 1992, following a cross-sectional study, using various biomarkers in five health centre districts. The Koseisho cohort comprises approximately 170,000 people aged 40-59 or 40-69 in 12 different health centre districts. The data are linked with the mass screening program registry data every year, and the sera and buffy coats collected at the beginning of the study will be stored at -80 degrees C for at least 10 years. We intend to integrate various sources of information about health conditions for the prevention of chronic diseases in these cohort areas. Nutritional practices are one of our main interests, and repeated surveys by different methods are planned. Although all death certificates are collected through the health centres, disease registration committees were established in each district to register incident cases of both cancer and certain cardiovascular diseases. Representative population-based prospective studies in Japan are briefly reviewed and introduced.