为确定影响下颌鳞状细胞癌（LGSCC）患者局部复发和生存的临床因素，并确定骨浸润是否为其独立的预后因素，本回顾性研究纳入了2013年6月至2015年12月间就诊于北京大学口腔医院的104名LGSCC患者。所有患者均被追踪随访超过3年。骨浸润程度以术前影像学资料（CT和全景放射照片）进行评估。骨浸润程度分为四个类别：无骨浸润、皮质骨浸润、骨髓腔浸润和下颌管浸润。根据肿瘤中心位置将其分为两类：前颌骨浸润（下颌孔前区）和后颌骨浸润（下颌孔后区）。使用Mann-Whitney U检验比较不同浸润深度组之间的差异。P值<0.05被认为具有统计学意义。采用Kaplan-Meier生存分析方法绘制生存曲线，利用COX回归探索LGSCC预后因素的风险比（HR）和95%置信区间（CI）。随访结果显示，此组LGSCC患者的1、3和5年生存率分别为91%、84%和82%。32.7%的患者（34/104）出现颈淋巴结转移。下颌骨前区的颈淋巴结转移率为12.5%（2/16），而后区为36.4%（32/88）（P<0.05）。单变量和多变量COX分析显示，N分期和局部复发是LGSCC患者的预后因素（P<0.05）。随着下颌骨浸润程度的增加，患者的预后变差。N分期和局部复发是LGSCC的预后风险因素。LGSCC颈淋巴结转移的发生率与原发肿瘤位置有关。可以得出结论，位于下颌骨后区的肿瘤可能比前区更容易发生颈淋巴结转移。因此，应针对LGSCC不同部位采取不同水平的颈淋巴结清扫策略。

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.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).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.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).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.