The Japanese Guidelines for Breast Cancer Screening

Abstract

Objective: The incidence of breast cancer has progressively increased, making it the leading cause of cancer deaths in Japan. Breast cancer accounts for 20.4% of all new cancers with a reported agestandardized rate of 63.6 per 100 000 women. Methods: The Japanese Guidelines for Breast Cancer Screening were developed based on a previously established method. The efficacies of mammography with and without clinical breast examination, clinical breast examination and ultrasonography with and without mammography were evaluated. Based on the balance of the benefits and harms, recommendations for populationbased and opportunistic screenings were formulated. Results: Five randomized controlled trials of mammographic screening without clinical breast examination were identified for mortality reduction from breast cancer. The overall relative risk for women aged 40-74 years was 0.75 (95% CI: 0.67-0.83). Three randomized controlled trials of mammographic screening with clinical breast examination served as eligible evidence for mortality reduction from breast cancer. The overall relative risk for women aged 40-64 years was 0.87 (95% confidence interval: 0.77-0.98). The major harms of mammographic screening were radiation exposure, false-positive cases and overdiagnosis. Although two case-control studies evaluating mortality reduction from breast cancer were found for clinical breast examination, there was no study assessing the effectiveness of ultrasonography for breast cancer screening. Conclusions: Mammographic screening without clinical breast examination for women aged 40-74 years and with clinical breast examination for women aged 40-64 years is recommended for population-based and opportunistic screenings. Clinical breast examination and ultrasonography are not recommended for population-based screening because of insufficient evidence regarding their effectiveness.

Systematic reviews as a ‘lens of evidence’: Determinants of benefits and harms of breast cancer screening

“…The sensitivity of CBE was improved by spending more time on examination and by using a thorough technique . The specificity of CBE was above 88% in all the reviews . compared to no screening, CBE was associated with a higher rate of false‐positive biopsies and FPR .…”

“…b , Appendix 4). All except one systematic review of observational evidence report BCM reduction of 17–49% in this age group …”

“…Similar to overdiagnosis, FPR and rate of false‐positive biopsies varied significantly by screening interval, age of initiation, previous screening experience and source of evidence (Appendix 7). The ranges of non‐cumulative FPR were 6.5–8% with annual screening and 1–11% with biennial screening (Appendix 7), and of cumulative FPR (after 10 years or lifetime) were 3–63% with annual and 7–60% with biennial screening (Fig. ).…”

“…c , Appendix 4). There was no review reporting all‐cancer mortality reduction in this age group, and two meta‐analyses concluding on statistically non‐significant reduction in all‐cause mortality . Seven reviews assumed that mammography screening has a higher benefit for women older than 50 years and a lower benefit for younger women, because of the lower test sensitivity of mammography due to higher breast density and, possibly, faster‐growing tumours.…”

“…d , Appendix 4). A review by Galit et al . (2007) concluded on lower BCM among women aged 75–84 years who underwent screening compared to those who did not, whereas other reviews concluded on no clear benefit for women older than 70 years .…”