Radical radiotherapy alone in non-operable breast cancer: the major impact of tumor size and histological grade on prognosis.

This retrospective study involved 319 non-operable breast cancer patients treated by radiotherapy alone with doses of 65 Gy at the Institut Gustave-Roussy (IGR). These patients either had operable tumors but were unfit for general anesthesia or had inoperable tumors due to local contraindications. Most of them had advanced tumors: 21% less than 7 cm; 30% N2 or N3; 30% with inflammatory carcinomas. The 5- and 10-year survival was 40 and 19%, respectively. The local and distant relapse-free rate was 56 and 33% at 5 years and 44 and 28% at 10 years respectively. Results were analyzed according to tumor size, clinical node involvement, histologic grade, age, skin invasion and tumor dose. A multivariate analysis demonstrated that tumor size (p = 10(-3)) and histological grade (HG) (p = 10(-2)) were both significant factors predicting local relapse. Histological grade (p = 10(-3)), tumor size (p = 10(-2)) and clinical node involvement (p = 10(-2)) were the most significant factors predicting distant relapses. An individual risk (IR) of local recurrence and of distant recurrence was defined according to the above factors and was demonstrated to be good prognostic index. Tumor doses above 80 Gy did not increase local control. We recommend the general use of histological grading as it seems important for prediction of local and distant control in patients treated by radiotherapy alone.