The role of regional nodal irradiation in the management of patients with early-stage breast cancer treated with breast-conserving therapy

Purpose: To determine the incidence of regional nodal failure (RNF) and indications for regional nodal irradiation (RNI) in patients with Stage I and II breast cancer treated with breast-conserving therapy (BCT). Methods and Materials: Four hundred fifty-six patients with Stage I/II breast cancer were treated with BCT at William Beaumont Hospital. All patients underwent excisional biopsy and 288 (63%) were reexcised. A Level I/II ipsilateral axillary lymph node dissection was performed on 431 patients (95%). Pathologically involved nodes were found in 106 (23%) cases (69 with one to three nodes and 37 with ≤ four nodes involved). All patients received whole breast irradiation (median dose 50 Gy) and 415 (91%) were boosted to the tumor bed (median total dose 60.4 Gy). Three hundred and sixty (79%) patients received breast alone irradiation and 96 (21%) also received RNI. The median axilla/supraclavicular fossa dose was 50 Gy. Results: With a median follow- up of 83 months 15 patients developed a RNF for a 5- and 8-year actuarial rate of 3 and 4%, respectively. The 5- and 8-year actuarial rates of axillary failure (AF) were 0.7 and 1.0%, respectively. The incidence of RNF or AF was not affected by the use of RNI in N0 or N1 patients with one to three positive nodes. Only in patients with four or more positive nodes was there a trend towards improved regional control with RNI (p = 0.09). However, patient numbers were extremely small, and this improvement was limited to a reduction in the rate of failure in the supraclavicular fossa (SCF) (20 vs. 0%, p = 0.04). Multiple clinical, pathologic, and treatment related factors were analyzed for an association with AF. On univariate analysis, AF was associated with the number of lymph nodes excised (p < 0.0001) estrogen receptor status (p = 0.0016), and pathologic node status (p = 0.0021). Conclusions: Regional nodal failure as the first site of failure is uncommon in patients with early-stage breast cancer treated with BCT with ≤ three positive lymph nodes and appears unaffected by RNI. For patients with four or more positive lymph nodes, a trend towards improved RNF was noted with RNI, primarily in the SCF. However, patient numbers were extremely small in all subsets analyzed. Additional studies are needed to further define the need for RNI in these Patients and help determine other factors associated with RNF.