[Clinical factors affecting the prognosis of lower gingival squamous cell carcinoma].

Objective: To define the clinical factors that influence local recurrence and survival in patients with lower gingival squamous cell carcinoma (LGSCC) and determine whether bone invasion is an independent prognostic factor for them.
Methods: A total of 104 patients with LGSCC hospitalized in Peking University Stomatology Hospital from June 2013 to December 2015 were enrolled in this retrospective study.All the patients were followed-up for more than 3 years.The degree of bone invasion was assessed using preoperative imaging data (CT and panoramic radiograph).The degree of bone invasion was divi-ded into four categories: no bone invasion, invasion of cortical bone, invasion of bone marrow cavity, and invasion of the mandibular canal.According to the central position of tumor, it was divided into two types: anterior mandibular invasion (anterior region of the mental foramen) and posterior mandibular invasion (posterior region of the mental foramen).
Results: of different invasion depth groups were compared using Mann-Whitney U test. P value < 0.05 was considered to be statistically significant.Kaplan-Meier survival analysis method was used to draw survival curve, and COX regression was used to explore the risk ratio ( HR ) and 95% confidence interval ( CI ) of prognostic factors of LGSCC.
Results: The follow-up results showed that the 1-, 3-, and 5-year survival rates of LGSCC in this group were 91%, 84%, 82%, respectively.32.7%(34/104) of patients had cervical lymph node metastasis.The cervical lymph node metastasis rate of the anterior segment of the mandible was 12.5%(2/16), and 36.4%(32/88) for the posterior segment of the mandible ( P < 0.05).Univariate and multivariate COX analysis showed that the N stage and local recurrence were the prognostic factors of LGSCC patients ( P < 0.05).
Conclusion: As the degree of mandibular invasion increases, the prognosis of patients with mandibular gum cancer becomes worse.N stage and local recurrence are prognostic risk factors for LGSCC.The incidence of cervical lymph node metastasis for LGSCC is related to the primary tumor location.It is concluded that tumors located at the posterior of the mandible might be more prone to cervical lymph node metastasis than the anterior of the mandible.Thus various levels of cervical lymph node dissection strategies should be adopted for different sites of LGSCC.