International Journal of Clinical Oncology · Nov 6, 2026

Self-reported eating speed and the risk of breast cancer among Japanese women: a retrospective cohort study from the LIFE Study

By Kawaguchi K, Maeda M, Oda F et al.

Background Eating speed has been linked to higher body mass index and unfavorable metabolic profiles, but its association with incident breast cancer has not been well characterized. Methods We conducted a retrospective cohort study using linked health check-up records and medical claims from 19 municipalities in the Longevity Improvement and Fair Evidence Study. Women aged ≥ 40 years who attended government-subsidized health check-ups (April 2016–March 2021) and answered an eating speed question were included. Eating speed was self-reported as faster, normal, or slower. Incident invasive breast cancer was identified using a validated claims-based algorithm. Cause-specific hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models comparing faster and slower versus normal eating speed with stepwise adjustment for age, lifestyle factors, and comorbidities. Results Among 243,737 women included in the analyses, 3213 (1.3%) developed breast cancer during follow-up. In the fully adjusted model, slower eating was associated with a lower risk of breast cancer compared with normal eating (HR 0.84, 95% CI 0.73–0.96), whereas faster eating showed no association (HR 1.02, 95% CI 0.93–1.10). The results were generally consistent across competing-risk and sensitivity analyses. Conclusion In this large cohort, slower self-reported eating speed was associated with a modestly lower risk of incident breast cancer. By providing one of the first large-scale longitudinal evaluations of the association between self-reported eating speed and breast cancer risk, this study addresses a gap in epidemiological evidence but does not establish that slower eating prevents breast cancer.

doi.org/10.1007/s10147-026-03237-2PubMed 42993238Populations