Evaluation of predictive factors for local tumour control after electron-beam-rotation irradiation of the chest wall in locally advanced breast cancer

Background and purpose: Different radiotherapy techniques are being used fo r chest wall irradiation after mastectomy. We review our results with the e lectron-beam-rotation technique in a series of 130 high risk breast cancer patients. The main end point of the study was local tumour control; seconda ry end points were disease free survival, and overall survival, as well as acute and late side effects. Material and methods: From January 1990 to June 1995, 89 patients underwent electron-beam-rotation irradiation of the chest wall after primary mastect omy and axillary lymph node dissection (group I) and 41 patients after exci sion of local recurrent breast cancer (group II) with 4 x 2.5 Gy/week to 50 Gy total dose (4-12 MeV electrons depending on the thickness of the chest wall). In addition, irradiation of local-regional lymph nodes and/or a loca l boost of 10 Gy were applied dependent on the resection and node status. Results: After a median follow up of 29 months (65% stadium III/IV) the 3 y ear local tumour control, disease free survival, and overall survival were 73%, 47%, and 75%, respectively. Local control in group I was 78% versus 60 % in group II. Significant predictors for local tumour control, disease fre e survival, and overall survival were resection status (RO versus R1/2) and estrogen receptor status (positive versus negative). In group I, tumour gr ading (GI-IIa versus GIIb-III) and estrogen receptor status were found to b e additional significant prognostic factors for complete resected tumours. Five patients developed symptomatic pneumonitis (< 4%) and one patient deve loped a chronic fistula at the resection. A significant correlation between the degree of acute skin reaction and persistent pigmentation was observed . Conclusion: In high risk breast cancer patients postoperative irradiation w ith the electron-beam-rotation technique of the chest wall is an effective therapy resulting in 78% local tumour control at 3 years for locally advanc ed breast cancer and 60 % for recurrent disease. The rate of acute and late toxicity is low. The degree of acute skin reaction correlates with the deg ree of persistent pigmentation. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.