Risk factors of developing a second malignancy following treatment of a first primary breast cancer

Background: breast cancer is the most prevalent cancer among iranian women,and is the fifth cause of cancer-related death in iran. most studies have reported an overall excess of 20-30% chance for a second primary cancer to develop in individuals with a first breast cancer. in this study,we evaluated different factors might have a role in increasing the incidence of a second malignancy after a first primary breast cancer in iran. methods: we considered 980 breast cancer patients from three cancer research centers in tehran,mashad and isfahan from sep 1995 till sep 2010. results: overall,94 second primary neoplasms observed. this analysis showed the existence of a modest excess in several neoplasms occurring after breast cancer. some treatment related factors,including radiotherapy or mastectomy,had statistically significant relation with development a secondary cancer. however,sub-analysis failed to prove such a relationship. conclusion: therefore,we can concluded that the risk of developing a second cancer is more dependent on genetic and environmental factors that caused the first primary cancer,rather than being dependent on type of treatment and other factors mentioned in this study.