[Interest of PET/CT scan fusion to assess mandible involvement in oral cavity and oro pharyngeal carcinomas]. / Intérêt de la fusion TEP/TDM dans l'exploration de l'envahissement mandibulaire des cancers de la cavité orale et de l'oropharynx.

UNLABELLED: The aim of the study is to assess mandible involvement in oral cavity and oropharyngeal carcinomas. OBJECTIVE: To evaluate interest of fusion of Positron Emission Tomography (PET) with Computed Tomography scan (CT scan). METHOD: Eight patients were included in this prospective study. Each patient underwent PET and CT scan of the head and neck before surgery including tumorectomy and mandibulectomy. We compared results of PET- CT fusion with histologic examinations. RESULTS: Oral cavity (6), oropharyngeal (2) carcinoma: Mandibular invasion was suspected by PET-CT in 3 cases, but was confirmed in histological examination in only 2 cases. In 5 cases, PET-CT did not find mandibular invasion; this was confirmed in histological examination in all cases. Sensibility of PET-CT fusion was 100%, specificity was 83%. Positive predictive value was 66% and negative predictive value was 100%. DISCUSSION: PET-CT fusion provided maximal sensitivity. Specificity was better than for MRI but less than CT-scan. There were no false negatives and the false positive rate was 33%. CONCLUSION: PET-CT fusion is interesting to predict mandible involvement. Further studies are necessary to confirm these preliminary results.

[Detection of the sentinal node in squamous-cell carcinoma of the oral cavity and oropharynx. Preliminary study]. / Détection du ganglion sentinelle dans les carcinomes épidermoïdes de la cavité buccale et de l'oropharynx. Etude préliminaire.

INTRODUCTION: The sentinel lymph node is defined as the first relay of the lymphatic drainage of the tumor. Isotopic detection of the sentinel lymph node and absence of its metastatic invasion should theoretically be predictive of total drainage of the tumor. The goal of this study was to evaluate sentinel lymph node detectability by lymphoscintigraphy in N0 and/or N1 squamous-cell carcinoma of oral cavity and oropharynx and to determine its negative predictive value. MATERIAL AND METHOD: Lymphoscintigraphy was used for sentinel lymph node detection. The procedure required peritumoral injection of technicium-labeled colloids to enable anatomical and cutaneous location of the sentinel lymph node. A one-way Tyco-Mallinckrodt probe was used for intraoperative detection of the sentinel lymph node. This prospective study included 21 patients with N0 or N1 squamous-cell carcinoma of the oral cavity and the oropharynx. The surgical attitude based on T and N was not modified in this prospective study without direct individual benefit for the patient. Neck dissection was achieved without difficulty. RESULTS: The sentinel lymph node was identified in 20 out of 21 subjects. The sentinel lymph node was not identified in one patient with recurrence T2N0M0 squamous-cell carcinoma of the oropharynx radiated 3 years earlier. The percentage of false-negatives was 12.5% (1 false-negative out of 8 positive patients), giving a sensibility of the detection method of 87.5% (IC (95%)=[47.35-99.68]). This false-negative patient had a T3N0M0 squamous-cell carcinoma of the oropharynx with a sentinel lymph node removed in territory III. Neck dissection revealed 1 N + R- in the sub-mandibular territory associated with 27 N-R-. The probability of not finding a metastatic node at neck dissection when the sentinel lymph node is not metastatic (negative predictive value) was 92.3% (12/13) (IC (95)=[63.97-99.81]). The specificity of the method was 100%, as was the positive predictive value, because no sentinel node was diagnosed positive wrongly on frozen sections among patients without true histological node metastasis. DISCUSSION: For routine care of patients with squamous-cell carcinoma of the oral cavity and the oropharynx detection of the sentinel lymph node is proposed primarily for patients with T1T2N0 staging. Larger tumors can modify the architecture and flow within the lymphatic ducts, and consequently even the concept of a sentinel lymph node. Systematic neck dissection is required or T3T4, even when N0. Our series of T1T2N0 tumors is too small to enable statistically significant conclusions. A low level of false-negative in a larger series would be necessary to propose this technique instead of convention neck dissection for T1T2 tumors of the oral cavity and oropharynx.