1. Introduction
Oral cavity squamous cell carcinoma (OSCC) is the most common oral cancer, and many treatments have been evaluated (1, 2). However, the optimal method for evaluating neck nodes after removal of primary oral cavity lesions in patients with early OSCC (stage T1 or 2) free from lymph node metastasis (N0) remains unclear. Neck node removal prevents clinical recurrence and significantly increases overall survival (OS) (3, 4). Metastasis to the cervical lymph nodes is very important in the prognosis, reducing survival by 50% (5). The risk of occult lymph node metastasis in OSCC patients of clinical stage N0 is 20–30% (6, 7).
Traditionally, elective neck dissection (END) was considered for patients with early stage OSCC. Several studies reported that this was better than watchful waiting (until metastasis developed) (8-10). END improved survival and reduced the recurrence rate. However, END may be an unnecessarily invasive approach for patients at low risk of lymph node involvement (8, 9). As END can affect shoulder motility and cause persistent pain and scarring, an alternative is desirable. Sentinel node biopsy (SNB) represents a compromise between END and watchful waiting, and has often been used to accurately detect occult neck node metastases (11, 12). SNB involves the injection of a radiotracer or methylene blue to identify the lymph nodes that drain first from the primary cancer (13, 14), and sensitivity and accuracy are high (15). However, long-term follow-up data are lacking, and the false-positive rate can reach 36% (15, 16). Few reviews or meta-analyses have compared the utility of SNB and END, which we thus address herein. We also performed detailed subgroup analyses by follow-up period.