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Tumorecomy with axillary dissection followed by locoregional irradiation is the standard treatment of T1 T2 ≤ 3 cm breast cancer. The optimum dose to the breast and the tumor bed remains controversial. To answer this question a phase III study was conducted in Lyon since 1986. Main criterias of inclusion were T1 T2 ≤ 3 cm with free margins on the pathological specimen, age no more than 70 years. Randomization was between two dose levels: Arm 1: whole breast irradiation 50 Gy/20 F/5 weeks (dose specified on the 95% ICRU isodose); Arm 2: same dose plus a boost of 10 Gy with electrons 9 or 12 Mev (isodose 90%). First end point will be local recurrence. For this criterium, on the assumption of a 1.2 annual rate of local recurrence, in patients with boost, and a 2.4 rate in those not receiving boost, with an annual censured rate of 1%, at one side sent, a type I error equal to 5% and a power of 85%, a number of 1014 patients must be included in the trial. Between 01/86 until 07/92, 1024 patients were enrolled in this trial. Randomization was performed with stratification on pTNM classification. The groups were comparable for know prognostic factors. Results The local relapse free survival after 5 years was 96.4% in the 60 Gy group (tested group) and 95.5% in the 50 Gy group (controlled group). The hazard ratio, adjusted for other prognostic factors was 0.31 (0.11 to 0.88—P = 0.028). The disease free survival after 5 years was 86%, in the 60 Gy and 82.2% in the 50 Gy group. The adjusted hazard ratio was 0.6 (0.38 to 0.96—P = 0.037) There was no significant difference for overall survival between the two groups. Telangiectasis grade I were present in 6% in the 50 Gy group and 12% in the 60 Gy group. This result suggests a trend in favor of the boost (60 Gy) in term of local control with a small and acceptable detrimental effect on cosmetic results. |
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