The Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) reported that the risks of breast cancer treatment in woman smokers may outweigh the benefits. The data used doses from published reports using a variety of treatment techniques. In our study, the risks of lung cancer and heart disease were determined from a modern era tangential-only technique.

Doses to the lung and heart were obtained for tangential radiotherapy to the breast or chest wall. The risk of lung cancer incidence and cardiac mortality were calculated by taking the ratio of our doses to those published by the EBCTG.

A total of 77 women were identified meeting our inclusion criteria. The mean combined whole lung dose was 2·0 Gy. The mean whole heart dose was 0·9 Gy. The estimated risk of lung cancer and cardiac mortality in a 50-year-old life-long smoker was estimated to be 1·5 and <1%, respectively.

Tangential only radiotherapy delivered substantially lower doses to the combined whole lung and whole heart than those reported by the EBCTCG. In this cohort, the risks of radiation induced lung cancer and heart disease are outweighed by the benefits of radiotherapy even in those that are smokers.