Postoperative Re-irradiaTion With and Without HYPERthermia: Toxicity, Quality of Life and Survival in Patients With Locoregional Recurrent Breast Cancer

In the Netherlands, breast cancer patients with locoregional recurrence (LRR) and high-risk factors are treated with postoperative re-irradiation with or without hyperthermia. Retrospective studies showed that 3-year locoregional control after postoperative re-irradiation with hyperthermia was 68-83%, and severe toxicity in up to 40% of LRR patients. Unfortunately, no prospective (randomized) data are available on clinical outcomes. Consequently, variation exists in hyperthermia-treatment and re-irradiation schedules. Prospective real-world data on oncological outcomes, toxicity and quality of life is highly needed for shared decision-making between patients and professionals. These data will be used in the design of a future randomized trial comparing postoperative re-irradiation and hyperthermia-treatment in high-risk LRR patients.

The optimal management of LRR breast cancer is multidisciplinary, and based on various prognostic risk factors and previous treatments. The surgical treatment of local recurrences is salvage mastectomy after previous breast-conserving therapy, or local excision after previous mastectomy. Regional treatment of tumor-positive lymph nodes consists of axillary radiotherapy and/or lymph node dissection. High-risk LRR patients have an indication for postoperative irradiation to improve locoregional control and disease-free survival. In previously irradiated high-risk LRR patients, postoperative re-irradiation is administered with or without hyperthermia in the Netherlands depending on the treating center and treating professional. Before the preoperative systemic treatment era, primary re-irradiation with hyperthermia was the evidence-based standard of care in high-risk unresectable LRR. Hyperthermia was used to increase the therapeutic efficacy of re-irradiation. The introduction of preoperative systemic therapy in 2010 resulted in more resectable high-risk LRRs. This resulted in postoperative re-irradiation instead of primary re-irradiation in LRR patients, including variation in the use of hyperthermia. There is no evidence-based standard of care regarding the combination of postoperative re-irradiation with or without hyperthermia in high-risk LRR patients. The major problem is that only retrospective data and no prospective (randomized) data is available on oncological outcomes (survival and recurrence) and toxicity following postoperative re-irradiation and hyperthermia. Consequently, there is a high need to assess oncological outcomes and toxicity of postoperative re-irradiation with or without hyperthermia in a randomized controlled trial (RCT). So far, an RCT has not been feasible due to the large variation in postoperative re-irradiation and hyperthermia, and preferences regarding hyperthermia-treatment by professionals. In the RT-HYPE study, the investigators evaluate oncological outcomes, toxicity and quality of life in high-risk LRR patients, including the harmonization of hyperthermia-treatment. The results of the RT-HYPE study are needed for the optimization of the shared decision making (SDM) process on post-operative re-irradiation with or without hyperthermia, between professionals and patients. In addition, these results allow to set-up a future RCT comparing postoperative re-irradiation with and without hyperthermia treatment.