Equivalence randomized trial comparing treatment based on sentinel node biopsy versus neck dissection in operable T1-T2N0 oral and oropharyngeal cancer.

6501 Background: Although sentinel node (SN) biopsy is known to be accurate in operable oral and oropharyngeal cT1-T2N0 squamous cell carcinomas (OC), the oncological equivalence of a treatment based on SN compared to that based on neck dissection (ND) has to be evaluated. Methods: A prospective multicenter randomized medico economic study included patients with OC operated of primary tumor and systematic neck dissection in ND-arm (standard treatment) versus patients operated of primary tumor and SN biopsy only if negative or ND if SN biopsy positive (SN-arm, experimental treatment). Primary endpoint was neck-relapse-free survival at 2 years and 5 years. Hypothesis of equivalence was tested with a delta of 10%. Functional outcomes were assessed by comparing the length of the hospital stay, the number of physiotherapy prescriptions and dysfunctions in neck and shoulder scales during the 2 post-operative years. Results: Out of 307 included patients in 10 hospital centers, 279 evaluable cases showed a neck-relapse-free survival at 2 years and 5 years respectively of 89,6% (95%CI: 0.827; 0.938) and 89,6 %, (95%CI: 0.827; 0.938) in the ND-arm (14 neck relapses out of 139 patients) and of 90,7% (95%CI: 0.842; 0.946) and 89,4% (95%CI: 0.823; 0.938) in the SN-arm (13 neck relapses out of 140 patients). The survival difference between the two arms was less than the 10% expected interval, confirming the equivalence with p = 0.008. The median length of hospital stay was 7 days (ext. 3-30) in SN-arm and 8 days (ext. 2-94) in ND-arm (Wilcoxon’s test, p = 0.001). The other functional outcomes were statistically worse in the ND-arm at the 2nd, 4th and 6th postoperative months. There was no more difference at 12 months and later. Conclusions: This study demonstrated the oncological equivalence of the SN approach compared to the ND approach in a multicenter study with a lower morbidity and care consumption in the SN approach during the 6 first post-operative months. Treatment based on sentinel node biopsy is established as a standard of care in OC. Clinical trial information: NCT02855723 .