Increased cardio and cerebrovascular mortality in breast cancer patients treated with postmastectomy radiotherapy – 25 year follow-up of a randomised trial from the South Sweden Breast Cancer Group

Aim of the studyTo analyse late morbidity and mortality in pre and post-menopausal breast cancer patients treated with postmastectomy radiotherapy, with emphasis on side-effects from the heart, cerebrovascular and respiratory systems.MethodsLong term follow-up of two randomised, clinical trials with 1100 patients was carried out. Pre-menopausal women were allocated to radiotherapy (RT), RT + oral cyclophosphamide (RT + C) or cyclophosphamide only (C). Post-menopausal women were allocated to RT, RT + Tamoxifen for one year (RT + Tam) or tamoxifen only (Tam). Information on admission to hospital, mortality and causes of death was obtained from national registers.ResultsAfter 25 years, adding RT to cyclophosphamide in pre-menopausal women raised the mortality from heart disease from zero to 0.8% (p = 0.04). In post-menopausal women, adding RT to Tam raised the mortality from heart disease from 10.5% to 18.4% (p = 0.005). In post-menopausal women mortality due to cerebrovascular disease increased from 3.4% to 8.7% by adding RT to Tam (p = 0.015). The differences were not evident until in the second decade of follow-up. In spite of differences in specific causes of death, there were no significant differences between the treatment arms concerning morbidity or overall mortality.ConclusionPostmastectomy radiotherapy to the chest wall and loco-regional lymph nodes including the parasternal lymph nodes as delivered in the end of the seventies did not reduce overall mortality, but gave a significantly increased risk of death from heart and cerebrovascular disease, which appeared during the second decade after radiotherapy.