Level IIb Metastases in cN0 Oral Squamous Cell Carcinoma: Multicenter Retrospective Study.

ImportanceNeck dissection is a common surgical treatment for patients with oral squamous cell carcinoma (OSCC). Due to the low incidence of level IIb metastases and the risk of injury to the spinal accessory nerve during level IIb dissection, the need for preventive neck dissection of this area has been discussed.ObjectiveThis study aimed to verify the incidence of level IIb metastases in patients with cN0 OSCC and to discuss the need for excision.DesignRetrospective cohort study.SettingThis study was conducted at 3 centers: the Department of Oral and Maxillofacial Surgical Oncology at the Institute of Science Tokyo Hospital, the Department of Oral and Maxillofacial Surgery at Kobe University Graduate School of Medicine, and the Department of Clinical Oral Oncology, Hokkaido Cancer Center.ParticipantsIn total, 222 patients with cN0 OSCC underwent supraomohyoid neck dissection (SOHND) between 2013 and 2021.Main Outcome MeasuresIncidence of level IIb metastases in patients with cN0 OSCC.ResultsLymph node metastasis was confirmed in 57 patients (25.7%). Two patients (0.9%) had level IIb metastasis. The primary site in these cases was the tongue in 1 case and the lower gingiva in the other, both with advanced cT4 primary tumors. Isolated level IIb metastasis was observed in tongue OSCC samples. Both patients with level IIb metastases experienced primary recurrence. The 5 year overall survival rates for pN(-) and pN(+) patients were 80.6% and 74.3%, respectively ( = .229). The 5 year disease-specific survival rates for the pN(-) and pN(+) patients were 89.6% and 77.2%, respectively ( = .057).Conclusions and RelevanceLevel IIb lymph node involvement in clinical N0 neck cancers is rare. Thus, SOHND may be adequate for most patients with OSCC. Therefore, level IIb dissection may be omitted in patients with cN0 in early-stage OSCC.