Impact of fraction size on cardiac mortality in women treated with tangential radiotherapy for localized breast cancer

Abstract

Purpose: To determine whether fraction size affects the risk of cardiac mortality in women treated with adjuvant radiotherapy (RT) for left-sided breast cancer.

Methods and materials: A population-based retrospective study of women with a diagnosis of localized breast cancer treated with adjuvant RT in British Columbia from 1984 to 2000. Cases were identified from the British Columbia Cancer Agency database. Overall and cardiac-specific survival were compared for women treated with RT for left- vs. right-sided breast cancer. We analyzed the impact of age (<or=60 vs. >60 years) at diagnosis and RT fraction size (<or=2 vs. >2 Gy) on risk of fatal cardiac events.

Results: We identified 3,781 women with left-sided and 3,666 women with right-sided breast cancer who received adjuvant RT. Median follow-up was 7.9 years. There were 52 vs. 47 breast cancer deaths in women treated for left- and right-sided breast cancer, respectively. There was no significant difference in cardiac mortality for women <or=60 or >60 years of age who received adjuvant RT for left-sided vs. right-sided cancer. There was no difference in cardiac mortality for women who received adjuvant RT with fraction sizes <or=2 vs. >2 Gy for left- or right-sided cancer.

Conclusions: There was no evidence for increased risk of cardiac mortality in women treated with adjuvant RT after a median follow-up of 7.9 years in our cohort. Hypofractionated adjuvant RT regimens did not significantly increase the risk of cardiac mortality.