Rate of Submandibular Gland Involvement in Oral Squamous Cell Carcinoma

Purpose: Whether the submandibular gland (SMG) can be preserved during neck dissection in the surgical treatment of oral squamous cell carcinoma (OSCC) is controversial. This study investigated the SMG involvement rate and provides a basis for preserving the SMG during neck dissection in appropriate cases of OSCC. Materials and Methods: A comprehensive systematic review was conducted on the PubMed and MEDLINE, Embase, and Cochrane Library databases for studies on SMG involvement in OSCC published before December 2017 with a data analysis technique. Predictor variables were numbers of patients and resected SMGs, primary site, and tumor, node, and metastasis stage. Outcome variables were the number of involved SMGs and mode of involvement. Other variables, namely first author, publication year, mean age, and condition of neck lymph nodes at level Ib, also were extracted. A random-effects model was used to analyze the rate of SMG involvement in OSCC. Results: Twelve studies involving 2,126 patients with OSCC who underwent neck dissection were included in the study. Fifty-two SMGs were involved, and the pooled involvement rate was 2% (I-2 = 73%; 95% confidence interval [CI], 1-3). Forty-eight SMGs were involved through direct spread from the primary site or extracapsular spread of positive lymph nodes, and the pooled involvement rate was 1.9% (I-2 = 72%; 95% CI, 0.9-3.1). Except for direct spread, 4 SMGs were involved through the intraglandular lymph node or carcinoma growing along Wharton ducts, and the pooled involvement rate was only 0.1% (I-2 = 0%; 95% CI, 0-0.2). Conclusions: The rate of SMG involvement in OSCC is very low, and the most common mode of involvement is by direct spread. The SMG might be preserved during neck dissection in OSCC when it is unlikely to be involved through direct spread. (C) 2018 American Association of Oral and Maxillofacial Surgeons