A Clinical Trial of Breast Radiation Therapy Versus Breast and Regional Radiation Therapy in Early-Stage Breast Cancer: The MA20 Trial

Abstract

Rationale There is currently considerable variation in the use of radiation therapy (RT) in early-stage breast cancer. Randomized trials1-3 and a metaanalysis4 of patients receiving systemic therapy have shown that RT after mastectomy improves survival compared with mastectomy without RT. At the same time, randomized trials have shown that breastconserving surgery (BCS) plus RT is equivalent to mastectomy.5-8 The RT in the BCS trials was generally restricted to the breast alone and most patients had node-negative breast cancer. Therefore, it is possible that adding regional RT may improve survival compared with breast-alone RT after BCS plus systemic therapy. Modern breast cancer treatments also involve more frequent use of anthracycline chemotherapy or combined chemohormonal therapy. Whether adding regional RT after anthracycline chemotherapy improves survival or further increases toxicity is not known. Extending the RT volume could possibly increase the risk of pneumonitis, lymphedema, and for patients with left-sided breast cancer, cardiac disease.9,10 The MA20 trial will determine the appropriate volume of RT for women treated with BCS and systemic therapy and will determine the effects of adding regional RT on survival and quality of life. Careful attention to RT technique is an important element of the MA20 trial as the survival benefit of postmastectomy RT in older randomized trials using outdated techniques appears to have been nullified by late cardiac mortality.11,12 Each patient has a review of the RT quality that considers the target volume included, normal tissues excluded, and dose homogeneity parameters. This review is conducted in real-time so that modifications to a patient’s treatment to ensure compliance with the treatment protocol specifications can be made prior to the start of treatment. The National Cancer Institute of Canada Clinical Trials Group (NCIC-CTG) is piloting a Webbased, real-time review process.