Radiotherapy in Early Breast Cancer
Abstract: Radiotherapy (RT) after mastectomy has been part of the treatment for early breast cancer since the 1940s. The treatment reduces the risk of loco-regional recurrences, but implies risk of late side effects that can begin decades after RT. Aims of the thesis were: - To analyse the long term effects of postmastectomy radiotherapy and systemic treatment for 1100 stage II breast cancer patients in two randomised, clinical studies initiated in 1978, SBII:I pre and post. - To investigate the preventive effect of pentoxifylline (PTX) and vitamin E on late side effects from radiotherapy in breast cancer patients in a randomised trial. - To evaluate non breast cancer morbidity and mortality in patients participating in the SBII:I trials. Results: With 20 year follow-up, RT reduced loco-regional recurrences by 70%, but no improvement in overall survival in irradiated patients was seen. Treatment with PTX was safe and gave minor side effects. In spite of short follow-up, positive effect of PTX was seen on arm volume. All patients had better shoulder mobility than expected. We found increased mortality from heart disease and cerebrovascular disease in irradiated patients, with 10-20 years latency. Hospital care due to non fatal morbidity was not increased. Conclusion: RT is an essential part of the loco-regional treatment of breast cancer. RT in the 70s increased non breast cancer mortality. Modern RT with smaller target volume and CT based 3D dose planning give substantially lower dose to heart, coronary arteries and lung, and fewer late side effects are expected.
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