Recent Increase in the Breast Cancer Incidence Among Japanese Women Seems to Correlate With the Prevalence of Drinking and Smoking Habits, but Not Obesity, as a Modern Lifestyle

Abstract

ObjectivesWe have recently reported that age-specific incidence rates of breast cancer among Japanese women clearly increased from 2000 to 2015 in a bimodal distribution pattern with two peaks at the age groups of 45 to 49 and 60 to 64 years. The present study aimed to assess the association of age-specific breast cancer incidence rates with the prevalence of obesity and drinking and smoking habits among Japanese women, compared with those of uterine body, colon and lung cancers. MethodsAge-specific cancer incidence and mortality rates and the prevalence of obesity and drinking and smoking habits were obtained from national data published by Cancer Information Services or National Institute of Health and Nutrition of Japan. Linear correlations of annual rates from 2005 to 2015 of the 10-year age-specific cancer incidence and mortality with the prevalence of obesity (body mass index, 25 and over) and drinking (alcohol, 20g and over 3 times or more a week) and smoking habits during the same 10-year period or the 10-year period 10 years before the cancer incidence and mortality were assessed by Pearson’s correlation coefficients. ResultsSignificant (p < 0.05) and positive correlations were found between breast cancer incidence and drinking habits during the same period at the age of 50–59 (r = 0.901), 60–69 (r = 0.808) and 70–79 years (r = 0.643) and during the 10-year-before period at 50–59 (r = 0.676); between the incidence and smoking habits during the 10-year-before period at 40–49 (r = 0.897), 50–59 (r = 0.731) and 60–69 (r = 0.696); between the mortality and drinking habits during the same period at 30–39 (r = 0.739), 60–69 (r = 0.817) and 70–79 (r = 712); and between the mortality and smoking habits during the same period at 30–39 (r = 0.733) and during the 10-year-before period at 60–69 (r = 0.663). Similar but less positive correlations for uterine body cancer or more positive correlations for male lung cancer were found. The prevalence of male drinking and smoking habits was decreasing during the 20 years. No positive correlations were found between the breast cancer incidence or mortality and the prevalence of obesity. ConclusionsThe present ecological study demonstrated that the prevalence of drinking and smoking habits, but not obesity, as a modern lifestyle correlated with the recent increase in the age-specific breast cancer incidence among Japanese women. Funding SourcesNone.