Re-irradiation and hyperthermia after surgery for recurrent breast cancer

Purpose: Evaluation of efficacy and side effects of combined re-irradiation and hyperthermia electively or for subclinical disease in the management of locoregional recurrent breast cancer.

Methods and materials: Records of 198 patients with recurrent breast cancer treated with re-irradiation and hyperthermia from 1993 to 2010 were reviewed. Prior treatments included surgery (100%), radiotherapy (100%), chemotherapy (42%), and hormonal therapy (57%). Ninety-one patients were treated for microscopic residual disease following resection or systemic therapy and 107 patients were treated electively for areas at high risk for local recurrences. All patients were re-irradiated to 28-36Gy (median 32) and treated with 3-8 hyperthermia treatments (mean 4.36). Forty percent of the patients received concurrent hormonal therapy. Patient and tumor characteristics predictive for actuarial local control (LC) and toxicity were studied in univariate and multivariate analysis.

Results: The median follow-up was 42months. Three and 5year LC-rates were 83% and 78%. Mean of T90 (tenth percentile of temperature distribution), maximum and average temperatures were 39.8°C, 43.6°C, and 41.2°C, respectively. Mean of the cumulative equivalent minutes (CEM43) at T90 was 4.58min. Number of previous chemotherapy and surgical procedures were most predictive for LC. Cumulative incidence of grade 3 and 4 late toxicity at 5years was 11.9%. The number of thermometry sensors and depth of treatment volume were associated with acute hyperthermia toxicity.

Conclusions: The combination of re-irradiation and hyperthermia results in a high LC-rate with acceptable toxicity.