The impact of superficial injections of radiocolloids and dynamic lymphoscintigraphy on sentinel node identification in oral cavity cancer: a same-day protocol.

AIM: To evaluate the role of dynamic lymphoscintigraphy with a same-day protocol for sentinel node biopsy in oral cavity cancer. METHODS: Twenty-two consecutive patients affected by cT1-2N0 squamous cell carcinoma of the oral cavity were enrolled between September 2001 and November 2005. After a local anaesthetic (10% lidocaine spray), a dose of 30-50 MBq of Tc human serum albumin nanocolloid, in ml saline, was injected superficially (1-2 mm subendothelial injection) into four points around the lesion. Dynamic lymphoscintigraphy was acquired immediately (256x256 matrix, 5 min pre-set time, LEGP collimator) in lateral and anterior projections. The imaging was prolonged until the lymph nodes of at least two neck levels were visualized (time required min). About 3 h later (same-day protocol) the patients had a radioguided sentinel node biopsy. Elective neck dissection was performed in the first 13 patients; whereas the last nine patients had elective neck dissection only if the sentinel node was positive. Sentinel nodes were dissected into 1 mm thick block sections and studied by haematoxylin & eosin staining and immunohistochemistry (anticytokeratin antibody). RESULTS: The sentinel nodes were found on the 1st neck level in 13 cases, on the 2nd neck level in eight cases, and on the 3rd neck level in one case (100% sensitivity). The average number of sentinel nodes was 2.2 for each patient. The sentinel node was positive in eight patients (36%); with six of them having the sentinel node as the exclusive site of metastasis. No skip metastases were found in the 14 patients with negative sentinel node (100% specificity). CONCLUSION: Our preliminary data indicate that superficial injections of radiocolloid and dynamic lymphoscintigraphy provide a high success rate in sentinel node identification in oral cavity cancers. Dynamic lymphoscintigraphy helps in distinguishing sentinel node from second-tier lymph nodes. The same-day protocol is advisable in order to correctly identify the first sentinel node, avoiding multiple and unnecessary node biopsies, without reducing sensitivity.