[Optimal treatment of the axilla after positive sentinel lymph node biopsy in early invasive breast cancer. Early results of the OTOASOR trial].

INTRODUCTION: Sentinel lymph node biopsy alone has become an acceptable alternative to elective axillary lymph node dissection in patients with clinically node-negative early-stage breast cancer. Approximately 70 percent of the patients undergoing breast surgery develop side effects caused by the axillary lymph node dissection (axillary pain, shoulder stiffness, lymphedema and paresthesias).

AIM: The current standard treatment is to perform completion axillary lymph node dissection in patients with positive sentinel lymph node biopsy. However, randomized clinical trials of axillary dissection versus axillary irradiation failed to show survival differences between the two types of axillary treatment. The National Institute of Oncology, Budapest conducted a single centre randomized clinical study. The OTOASOR (Optimal Treatment of the Axilla - Surgery or Radiotherapy) trial compares completion axillary lymph node dissection to axillary nodal irradiation in patients with sentinel lymph node-positive primary invasive breast cancer.

METHOD: Patients with primary invasive breast cancer (clinically lymph node negative and less than or equal to 3 cm in size) were randomized before surgery for completion axillary lymph node dissection (arm A-standard treatment) or axillary nodal irradiation (arm B-investigational treatment). Sentinel lymph node biopsy was performed by the radio-guided method. The use of blue-dye was optional. Sentinel lymph nodes were investigated with serial sectioning at 0.5 mm levels by haematoxylin and eosin staining. In the investigational treatment arm patients received 50Gy axillary nodal irradiation instead of completion axillary lymph node dissection. Adjuvant treatment was recommended and patients were followed up according to the actual institutional guidelines.

RESULTS: Between August 2002 and June 2009, 2106 patients were randomized for completion axillary lymph node dissection (1054 patients) or axillary nodal irradiation (1052 patients). The two arms were well balanced according to the majority of main prognostic factors. Sentinel lymph node was identified in 2073 patients (98.4%) and was positive in 526 patients (25.4%). Fifty-two sentinel lymph node-positive patients were excluded from the study (protocol violation, patient's preference). Out of the remaining 474 patients, 244 underwent completion axillary lymph node dissection and 230 received axillary nodal irradiation according to randomization. The mean length of follow-up to the first event and the mean total length of follow-up were 41.9 and 43.3 months, respectively, and there were no significant differences between the two arms. There was no significant difference in axillary recurrence between the two arms (0.82% in arm A and 1.3% in arm B). There was also no significant difference in terms of overall survival between the arms at the early stage follow-up.

CONCLUSIONS: The authors conclude that after a mean follow-up of more than 40 months axillary nodal irradiation may control the disease in the axilla as effectively as completion axillary lymph node dissection and there was also no difference in terms of overall survival.