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 for chest wall irradiation after mastectomy. We review our results with the electron-beam-rotation technique in a series of 130 high risk breast cancer patients. The main end point of the study was local tumour control; secondary 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 mastectomy and axillary lymph node dissection (group I) and 41 patients after excision 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 local 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 year 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 free survival, and overall survival were resection status (R0 versus R1/2) and estrogen receptor status (positive versus negative). In group I, tumour grading (GI-IIa versus GIIb-III) and estrogen receptor status were found to be additional significant prognostic factors for complete resected tumours. Five patients developed symptomatic pneumonitis (< 4%) and one patient developed 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 with the electron-beam-rotation technique of the chest wall is an effective therapy resulting in 78% local tumour control at 3 years for locally advanced 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 degree of persistent pigmentation.