Eur J Surg Oncol 2017 Jan 16
Eight-year follow up result of the OTOASOR trial: The Optimal Treatment Of the Axilla - Surgery Or Radiotherapy after positive sentinel lymph node biopsy in early-stage breast cancer: A randomized, single centre, phase III, non-inferiority trial.
Abstract
Introduction
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 of axillary lymph node dissection (cALND) to regional nodal irradiation (RNI) in patients with sentinel lymph node metastasis (pN1sn) in stage I-II breast cancer.
Patients and methods
Patients with primary invasive breast cancer (cN0 and cT ≤ 3 cm) were randomized before surgery for cALND (standard treatment) or RNI (investigational treatment). Sentinel lymph nodes (SN) were investigated with serial sectioning at 0.5 mm levels by hematoxylin-eosin staining. Investigational treatment arm patients received 50 Gy RNI instead of cALND. Adjuvant treatment and follow up were performed according to the actual guidelines. Between August 2002 and June 2009, 1054 patients were randomized for cALND and 1052 patients for RNI. SN was evaluated in 2073 patients and was positive in 526 patients (25.4%). 474 cases were evaluable (244 in the cALND and 230 in the RNI arm), and in the cALND group 94 of 244 patients (38.5%) who underwent completion axillary surgery has additional positive nodes. The two arms were well balanced according to the majority of main prognostic factors. Primary endpoint was axillary recurrence and secondary endpoints were overall survival (OS) and disease-free survival (DFS).
Results
Mean follow-up was 97 months (Q1-Q3: 80-120). Axillary recurrence was 2.0% in cALND arm vs. 1.7% in RNI arm (p = 1.00). OS at 8 years was 77.9% vs. 84.8% (p = 0.060), and DFS was 72.1% in cALND arm and 77.4% after RNI (p = 0.51). The results show that RNI is statistically not inferior to cALND treatment.
Conclusions
The long term follow-up results of this prospective-randomized trial suggest that RNI without cALND does not increase the risk of axillary failure in selected patients with early-stage invasive breast cancer (cT ≤ 3 cm, cN0) and pN1(sn). Axillary radiotherapy should be an alternative treatment for selected patients with sentinel lymph node metastases.
Related Questions
Under what circumstances would you pursue completion ALND in a patient with multiple positive sentinel nodes after breast-conserving surgery?
For clinical/imaging node-negative disease with 1-2 positive nodes, now there are 7 plus clinical studies (ACOSOG Z0011, AMAROS, OTOASOR, SENOMAC, IBCSG 23-01, AATRM, SINODAR-ONE) which have shown no difference in axillary recurrence, DFS with dissection, but higher lymphedema as expected. The most ...
Do you recommend axillary dissection for women with ER+ breast cancer and low risk Oncotype or Mammaprint if single node positive with only 1-2 SLN removed, to ensure <4 nodes positive?
No, I see no need to do dissection in this setting. Unless there is clinical or imaging evidence of gross disease, radiation should adequately control microscopic residual disease in the axilla.
Would you go back and do an axillary lymph node dissection if a sentinel lymph node biopsy showed a single lymph node with extracapsular extension?
For microscopic ECE, would manage with comprehensive RNI but if gross ECE, would favor dissection and then RT.
What treatment fields do you use for N1mi breast cancer after lumpectomy/SLNB?
We treat with modified tangents including level 1 and 2 nodes in tangential beam for micrometastases. ER, PR, and her2 neu or oncotype does influence the decision for micrometastases after lumpectomy.