Purpose: The value of adjuvant radiation therapy (RT) of the axilla and supraclavicular fossa is controversial in early-stage breast cancer. This retrospective study was undertaken to identify pathological risk factors that would predict which subsets of patients would benefit from regional nodal irradiation (RNI).
Methods and materials: A total of 1309 women with Stage I/II breast cancer underwent full axillary dissection and either mastectomy (n = 894) or breast-conserving surgery (n = 415). Of these, 712 patients received RNI. The median axilla/supraclavicular fossa dose was 50 Gy.
Results: The 10-year actuarial rate of axillary failure (AXF) was 0. 5% in N0 and 2.8% in N1 patients (p 5, also correlated with AXF; the respective rate was 4.3% vs. 1.2% (p = 0.0142). Neither the incidence of AXF nor the time to AXF was affected significantly by the use of RNI, but in N1 patients with retrieved nodes < or = 5, the rate of AXF was 8.3% without RNI vs. 0% with RNI (p = 0.2340). The 10-year actuarial rate of supraclavicular failure (SCF) was 1.2% in N0 and 6.3% in N1 patients (p = 0.0000). SCF was also associated with the extent of nodal involvement (p = 0.0031). The incidence of SCF was not significantly affected by the use of RNI. However, when the results of N1bii and N1biv patients were evaluated as a single group, the effect of RNI was significant (p = 0.0358). The rates of SCF without RNI were high in patients with N1bii or N1biv stage: 10% and 37.5% and, with RNI, 3.2% and 18.2%, respectively. These findings were reinforced by the various combinations of T- and N1-stage. The mean time to SCF was 53.6 months in the irradiated and 24.9 months in the nonirradiated patients (p = 0.0007).
Conclusions: After a complete axillary dissection, only N1 patients with retrieved nodes < or = 5 may be considered for axillary RT. Elective supraclavicular RT is suggested for patients with N1bii or N1biv stage. Supraclavicular irradiation decreases the incidence and delays the appearance of SCF.