| The relative rarity of squamous cell carcinoma (SCC) of the hard palate and maxillary alveolus compared with other primary sites in the oral cavity has resulted in a paucity of published data concerning its regional metastasis. Although it has long been believed that SCC of the hard palate and maxillary alveolus has a low nodal metastatic risk, recent studies yielded results higher than expected in this regard, putting their incidence on a par with other areas of the oral cavity. Some of these studies also emphasized the high risk of regional recurrence, which may be attributable to the presence of occult cervical metastasis. As elective neck dissection (END) has proven beneficial in patients with oral SCC at other sites, it may also be essential to apply this procedure to those with hard palate and maxillary alveolus SCC. However, the effects of END on SCC of the hard palate and maxillary alveolus have not been systematically evaluated because it is not yet a widely accepted routine procedure.Objective:Our retrospective study on hard palate and maxillary alveolus SCC was conducted to define the risk of both overall and occult cervical metastases; identify the clinicopathological features correlated with cervical metastasis; and evaluate the efficacy of routine dissection of cN0neck. In this article, we present our results and discuss them in light of a review of previous literature. We hope this research will help in regard to management of the neck in SCC at these two sites. Methods:Patients treated for SCC of the hard palate and maxillary alveolus from January2002to December2011were identified from the database of the Stomatological Hospital Affiliated Medical School, Nanjing University. Tumor, node, metastasis (TNM) stage, type of treatment, and other clinicopathological features were retrieved from medical records. Patients meeting the following criteria were included:primary SCC of the hard palate or maxillary alveolus, confirmed by pathologic examination and surgical treatment. Exclusion criteria were (1) prior surgery or radiotherapy,(2) SCC originating from the nasal cavity or paranasal sinuses, and (3) tumor invading the oropharynx, retromolar area, or buccal mucosa. Patients were followed up every three months over the first two years, every six months until the fifth year, and every year after the fifth year. Formalin-fixed, paraffin-embedded tissue blocks were retrieved from the archives of the Department of Pathology in our hospital. In situ hybridization was performed using a detection kit (Triplex International Biosciences, China) for high-risk human papillomavirus (HPV), following the manufacturer’s recommendations. This detection kit includes labeled probes for HPV type16/18. Statistical analysis used chi-square or Fisher’s exact tests for comparative groups. Analysis of difference in mean values was conducted by two-tailed t-test for independent samples. To define the association between clinicopathological features and overall survival, the Kaplan-Meier and Cox proportional hazards regression methods was used for univariate and multivariable analysis, respectively. In all cases, the level of alpha was set at0.05a priori. All analyses were performed in PASW18.0.Results:The study population comprised27men and40women, age ranging from37to82years (average,61.0). There were33cases of hard palate and34of maxillary alveolus SCC.17.2%(11/64) patients who underwent neck dissection were proven pathologically node-positive. Among patients with cervical metastases, four primaries were in the hard palate and seven in the maxillary alveolus. Bilateral metastases were detected in two patients.36.4%(4/11) of them had extracapsular extension of lymph nodes. Six of the13cN+patients were confirmed pathologically positive and five cN0patients were proven pN+after END.The incidence of neck diseases was34.6%in the pT4group, which was significantly higher than that in the pTl-T3group (5.3%, p<0.05). Vascular invasion was also significantly associated with cervical metastasis (p<0.05). There was a significant correlation between the pT status and occult cervical metastasis (28.6%versus3.0%, p<0.05). Furthermore, we found that cN0patients in the anemia group showed a higher risk of occult metastasis than those in the normal group (30.0%versus4.9%), with a statistical significance (p<0.05).Median follow-up time was45months (range,2-122). Local recurrence was confirmed in eight patients, and two had locoregional recurrence. The overall survival rate for all patients evaluated was88.0%(59/67). N status was found to be an independent predictor of overall survival on multivariable analysis. The presence of neck disease impaired prognosis significantly. For cN0and pN0patients, the expected five-year survival rate was91.1%; meanwhile, for pN+patients, this rate fell to only52.5%.Conclusions:Metastatic potential is highly correlated with T classification in hard palate and maxillary alveolus SCC. T4lesions have a higher cervical metastatic rate, comparable to that in other oral cavity sites. Based on these findings, we recommend routine, synchronous END (specifically, SOHND) for patients with T4primaries. The "watchful waiting" strategy is an alternative for patients with T1-T3lesions, assuming good patient compliance during follow-up. |
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