Long-Term Cardiovascular Mortality After Radiotherapy for Breast Cancer
What is the effect of radiotherapy for breast cancer on long-term cardiovascular mortality?
A total of 4,456 women who survived at least 5 years after treatment of breast cancer at the Institut Gustave Roussy between 1954 and 1984 were followed up for mortality until the end of 2003, for over 28 years on average. Multivariate analysis was performed to evaluate the radiotherapy effect on cardiovascular long-term mortality. This analysis was stratified on age at diagnosis (≤40, 41-50, 51-60, and ≥60 years) and calendar period of diagnosis (1954-1957, 1958-1976, and 1977-1984).
A total of 421 deaths due to cardiovascular diseases were observed, of which 236 were due to cardiac disease. Women who had received radiotherapy had a 1.76-fold (95% confidence interval [CI], 1.34-2.31) higher risk of dying of cardiac disease and a 1.33-fold (95% CI, 0.99-1.80) higher risk of dying of vascular disease than those who had not received radiotherapy. Among women who had received radiotherapy, those who had been treated for a left-sided breast cancer had a 1.56-fold (95% CI, 1.27-1.90) higher risk of dying of cardiac disease than those treated for a right-sided breast cancer. This relative risk increased with time since the breast cancer diagnosis (p = 0.05).
The authors concluded that radiotherapy, as delivered until the mid-1980s, increased the long-term risk of dying of cardiovascular diseases.
The study suggests that survivors who had received radiotherapy during their breast cancer primary treatment were at a higher risk of death from overall cardiovascular diseases, as compared to women who had not received radiotherapy. Furthermore, risk is increased for left-sided breast cancer radiotherapy as compared to right-sided tumor, and this difference increased with the duration of follow-up. However, it should also be noted that radiation therapy has significantly improved outcomes for breast cancer, both in conjunction with breast-conserving therapy and with post-mastectomy chest wall irradiation. At the present time, patients who opt for breast-conserving therapy and radiation should be provided with information regarding future cardiovascular risk, particularly if their anatomy is such that their heart/left anterior descending artery is likely to receive a substantial radiation dose.
Keywords: Survivors, Heart Diseases, Risk, Follow-Up Studies, Vascular Diseases, Cardiovascular Diseases, Breast Neoplasms, Mastectomy, Breast
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