Evaluation of sentinel node biopsy in accurately staging oral cavity squamous cell carcinoma

Abstract

Early oral cancer (EOC) is defined as patient diagnosed with a T1 or T2 primary and a clinically N0 neck – according to AJCC – TNM staging these are cancers <4 cm in maximum dimension and <10 mm in maximum depth of invasion (DOI) and both clinically/radiologically absent of neck nodal metastases.

Traditional treatment is surgery with appropriate resection of the primary and simultaneous excision of upper cervical neck nodes. However, following neck dissection microscopic metastases are present in only 15-20% of T1 and 25-35% of T2 cancers, respectively. Consequently, up to 80% of patients with a T1 cancer and 65% of T2 cancer undergo surgery to the neck with no oncological or survival benefit yet have been exposed to the risks and complications of a neck dissection.

Sentinel lymph node biopsy (SLNB) is a novel technique, which can overcome the disadvantages of unnecessary neck surgery. In this procedure a radioactive dye is injected around the primary tumour and single photon emission CT images are obtained to locate the SLN. The SLN is the “first node to drain the region of interest” with tumour spread to this SLN prior to spread to any other nodes of the basin – a concept well established in other solid organ cancers such as breast and melanoma. Handheld gamma probe is used to locate SLN during the surgery and typically one or two nodes are excised, if these prove to be negative the patient has been saved an unnecessary neck dissection. In the setting of a positive SLNB the patient proceeds to a neck dissection as a second surgical procedure. SLNB thus de-escalates treatment related morbidity while not compromising on oncological outcomes.