Radiation therapy after sentinel lymph node biopsy for early stage breast cancer using a magnetic tracer: Results of a single institutional prospective study of tolerance.

PURPOSE:. The aim of the study was, through a single institutional analysis of a large population of breast cancer patients, to assess the feasibility of and the tolerance to radiotherapy after the use of magnetic detection method for sentinel lymph node biopsy. MATERIAL AND METHODS:The super paramagnetic iron oxide particles database was collected prospectively and identified 520 cases from October 2013 to December 2016 at our institution. All of them received super paramagnetic iron oxide particles injection 20minutes before the surgical procedure and some of them received also isotope technique. Injection site for super paramagnetic iron oxide particles and isotope was periareolar. Among them, 288 patients received adjuvant radiotherapy. In our study, we evaluated the tolerance of postoperative radiotherapy. RESULTS:The median age of the patients was 64 years. The median follow-up period was 16 months (range: 1-42 months). Double detection of sentinel lymph node was done in the first 30 patients (10.4%). The sentinel lymph node identification rate was 99.7% (287 out of 288). There were 34 axillary lymph node dissections, of which 58.8% were realized straightaway. The total radiation dose was 50Gy EQD2 (range: 28.5-66Gy). Regarding the occurrence of radiodermatitis, 95.8% of patients had grade 0-2 radiodermatitis and 1% had grade 3. During follow-up, 19.4% of patients developed grade 1-2 post-therapeutic fibrosis (of which 92.9% grade 1). CONCLUSION:The results of this large-scale study show that the radiotherapy after sentinel lymph node biopsy using super paramagnetic iron oxide particles is feasible, and that no increase of the toxicity was observed.