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Pre-Operative Window of Endocrine Therapy to Inform Radiation Therapy Decisions in Older Women with Early Stage Estrogen Receptor Positive Breast Cancer, the POWER II Trial

Trial Status: active

This phase III trial compares the effect of adding pre-operative endocrine therapy to lumpectomy to surgery alone in determining treatment with post-operative radiation therapy in older women with early stage estrogen receptor positive (ER+) breast cancer. Historically, women over 65 with early-stage ER+ breast cancer are treated with surgery to remove the mass (lumpectomy) with or without radiation followed by endocrine therapy. Endocrine therapy lowers the amount of estrogen made by the body or blocks the use of estrogen by the tumor cells. This may help stop the growth of tumor cells that need estrogen to grow. Radiation therapy can be used after surgery to treat early-stage breast cancer and uses high-energy rays to kill cancer cells. Current guidelines indicate radiation is not necessary for in women 65 or older with early stage ER+ breast cancer taking endocrine therapy after surgery. However, if a patient does not get radiation therapy and is unable to take the prescribed number of years of endocrine therapy, the risk of recurrence increases. Alternatively, radiation therapy may not be needed if endocrine therapy is tolerable. Pre-operative endocrine therapy with lumpectomy may be effective in determining treatment with post-operative radiation therapy in older women with early stage ER+ breast cancer.