a significant trendP < 0·001
Compared with the lowest adherence category, a significant trend of decreasing BC risk with increasing adherence was observed in the crude model, overall (OR = 0·20 (0·14, 0·26), P < 0·001) in premenopausal women (OR = 0·20 (0·14, 0·26), P < 0·001) and in postmenopausal women (OR = 0·11 (0·10, 0·16), P < 0·001).