THURSDAY, Dec. 8, 2022 (HealthDay News) — The benefits of radiotherapy following breast-conserving surgery and systemic therapy for breast cancer in terms of fewer local recurrences are only seen during the first 10 years, with 30-year local recurrence and overall survival similar with or without radiotherapy, according to a study presented at the annual European Breast Cancer Conference, held from Nov. 16 to 18 in Barcelona, Spain.
Linda Williams, from the University of Edinburgh in the United Kingdom, and colleagues presented the long-term results of the Scottish breast conservation trial, which followed 585 patients (aged 70 years and younger). The patients were treated with breast-conserving surgery for early-stage breast cancer, followed by systemic therapy appropriate to estrogen receptor status, and then were randomly assigned to receive or not receive radiotherapy after surgery.
The researchers found that ipsilateral breast tumor recurrence was significantly lower in the radiotherapy arm (hazard ratio, 0.39; 95 percent confidence interval, 0.27 to 0.55), although there was evidence of a failure of the proportional hazards assumption (P < 0.0001). The log rank test was statistically significant (P < 0.0001). Differences emerged in the first 10 years after treatment during exploration of the hazard rate, but beyond that, the risk was similar in both arms. For overall survival, there were no significant differences observed up to 30 years (hazard ratio, 1.08; 95 percent confidence interval, 0.89 to 1.30; P = 0.43).
“Long-term follow-up is essential in breast cancer trials so that we can understand the full picture,” presenting author Ian Kunkler, also from the University of Edinburgh, said in a statement. “These data challenge the idea that radiotherapy improves long-term survival by preventing recurrences of cancer in the same breast.”
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