investigation on the association between breast cancer and consumption patterns of combined oral contraceptive pills in the women of isfahan in 2011

background: oral contraceptive pills are among the most popular contraceptive methods, but the fear of cancer and cardiovascular disease overshadows its continuous use among women. this study aimed to define the association between consumption patterns of combined oral contraceptives among women with breast cancer. materials and methods: this is an analytical case–control study conducted on 175 women with breast cancer, referring to seyed al shohada medical center and private clinics in isfahan to be treated and followed up in 2011, as well as 350 healthy women who were identical with the subjects in the study group regarding age and residential location. the data were collected using a researcher‑made questionnaire. content validity and cronbach’s alpha were employed to confirm validity and scientific reliability of the questionnaire, respectively. the data were analyzed by descriptive and analytical statistical methods through spss. results: the findings showed that there was a significant association between history of contraceptive pills’ consumption and incidence of breast cancer ( p < 0.001). it was shown that the risk of developing breast cancer is increased by 2.27‑fold among those with pills’ consumption compared to those with no history of that. it was also shown that pills’ consumption for 36-72 months increased the risk of breast cancer by 2.18‑fold, the age of the first use being less than 20 years increased the risk by 3.28‑fold, and time since the last use of less than 25 years increased the risk by 2.63‑fold. there was no significant association between duration of use, age of the first and last use, and time since the first and last use in the study and control groups. conclusion: the results showed that history of pills’ consumption is associated with incidence of breast cancer regardless of the consumption pattern. use of oral contraceptives pills at any age and for any duration can increase the risk of breast cancer.