ORIGINAL ARTICLE Non-sentinel node tumor invasion in oropharyngeal and oral cancer: risk of misdiagnosis of metastasis F. SANTAOLALLA 1 , J.M. SANCHEZ 1 , C. EREN ˜ O 2 , A. GONZALEZ 3 , M.L. RODRIGUEZ 3 , A. SANCHEZ 1 & A. MARTINEZ 1 1 Department of Otorhinolaryngology, 2 Department of Pathology and 3 Department of Nuclear Medicine, Basurto Hospital, School of Medicine, University of the Basque Country, Gurtubay, Bilbao, Spain Abstract Conclusion. The existence of patients with positive non-sentinel node indicates a risk of misdiagnosis of metastasis in oropharyngeal and oral cancer. Objectives. We attempted to confirm the usefulness of sentinel lymph node biopsy (SLNB) in oropharyngeal and oral cavity cancer to detect clinically occult metastases. Patients and methods. Twenty-two patients with a mean age of 57 (SD 13) years were studied prospectively. All presented T1T3 squamous cell carcinoma (SCC) of the oropharynx or oral cavity, and were cN0 on palpation and CT. A preoperative (24 h) lymphoscintigraphy was performed with 99mTc-labelled sulfur colloid injected around the primary tumor. Subsequently, we proceeded with tumor exeresis and detection of SLN following the procedures described in a previous paper. Results. We detected a total of 32 SLNs in 21 of 22 patients. Ipsilateral neck node location was observed in 18 patients and bilateral in 3. We observed 10 patients with true positive SLNs (3 patients had micrometastases), indicating occult metastases. We harvested a total of 454 nodes in our selective neck dissections, 19 of which presented metastatic invasion. We identified four patients with positive non-sentinel nodes. Keywords: Sentinel lymph node biopsy, oral cavity, oropharynx, cancer, metastasis Introduction Gould et al. [1] reported the concept of sentinel lymph node biopsy (SLNB) for the detection of metastases of parotid cancer. Cabanas [2] performed a study in patients with penile cancer using lymphos- cintigraphy. Morton et al. [3] introduced SLNB to detect occult nodal metastases of cutaneous mela- noma of trunk and extremities. Alex and Krag [4] were the first to describe radiolocation of the sentinel lymph node (SLN) in a patient with supraglottic carcinoma. Shoaib et al. [5] studied the SLN in two groups of patients with oral cancer: the first group received patent blue dye alone, whereas the second group was injected with both patent blue and Tc albumin colloids. These authors obtained promising results in their study. Alex et al. [6] determined the feasibility of SLN radiolocation in seven oral and one anterior larynx commissure cancers with N0 neck using technetium 99m as the radiotracer. At present, much work has been done. Nevertheless, many key questions remain unanswered. The aim of this study was to establish the usefulness of SLNB examination in oral and oro- pharyngeal cancer, with respect to accuracy in detecting clinically occult metastases in cN0 necks and any other hidden lymphogenic metastatic spread in the absence of radiotracer uptake (non-sentinel node). Therefore, we conducted a histopathological analysis of all neck nodes harvested after complete selective dissection from level I to V. Patients and methods Prospective patients group We established a prospective group of patients with SLN determination. This group consisted of 22 patients (21 men and 1 woman) diagnosed with squamous cell carcinoma (SCC) of the oropharynx Correspondence: Dr Francisco Santaolalla, Department of ENT, Basurto Hospital, School of Medicine, University of the Basque Country, Gurtubay, s/n 48013 Bilbao, Spain. Tel: 34 94 4006080. Fax: 34 94 6014545. E-mail: francisco.santaolalla@ehu.es Acta Oto-Laryngologica, 2008; 128: 11591164 (Received 5 December 2007; accepted 28 December 2007) ISSN 0001-6489 print/ISSN 1651-2551 online # 2008 Informa UK Ltd. (Informa Healthcare, Taylor & Francis AS) DOI: 10.1080/00016480801891710