Associations of increasing breast cancer incidence with the current drinking habits and the past smoking habits among Japanese women

We have reported that age-specific incidence rates of breast cancer among Japanese women increased from 2005 to 2015 in a bimodal distribution pattern, with two peaks in the pre- and postmenopausal age groups. The present study aimed to assess the associations of the increasing age-specific breast cancer incidence or mortality with the prevalence of obesity and drinking and smoking habits, compared with those in uterine body, female and male colon and lung cancers. 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, 20 g and over 3 times or more a week) and smoking habits were assessed by Pearson’s correlation coefficients during the same 10-year period (from 2005 to 2015) or the 10-year period 10 years before the cancer incidence and mortality were noted (from 1995 to 2005). Positive correlations (r>0.640) were found between the increasing breast cancer incidence and the drinking habit during the same period or the smoking habit during the period 10 years before. Similar but weaker correlations were found for the breast cancer mortality rate increasing with age. Positive correlations were found between the decreasing male lung cancer mortality rate and the smoking habit rate during the period 10 years before. The present ecological study indicated that the breast cancer incidence was associated with the current drinking habits and the past smoking habits among Japanese women.