Correlation of Lymph Node Density With Negative Outcome Predictors in Oral and Maxillofacial Squamous Cell Carcinoma
Roderick Youngdo Kim1, Brent Benson Ward2, Hans C Brockhoff3
1Resident, Department of Surgery, Section of Oral and Maxillofacial Surgery, University of Michigan, University of Michigan School of Dentistry, University of Michigan Medical School, Ann Arbor, MI.
Purpose:
Lymph node density is defined as the number of positive lymph nodes per total number of excised lymph nodes. In oral and maxillofacial cancer, there are recent data showing that increased lymph node density leads to worse outcomes for patients. However, data correlating lymph node density with other known risk parameters are lacking. This study investigated whether a direct correlation exists among cervical lymph node density, depth of invasion, perineural invasion, and extracapsular tumor spread.
Materials And Methods:
A retrospective chart review was undertaken to include all patients who underwent neck dissection with resection of primary oral and maxillofacial squamous cell carcinoma from January 2009 through July 2014. After applying the exclusion criteria, 286 patients were identified. Primary tumor depth of invasion, perineural invasion, and lymph node status, including extracapsular spread, were obtained from the standard pathology report. Descriptive statistics were applied. The association between 2 continuous tumor characteristics was summarized with the Pearson correlation coefficient, and the association between a continuous and a binary tumor characteristic was summarized with 2-sample t test. Statistical significance for the study was set at a P value less than .05.
Results:
Mean age at time of surgery was 63.9 ± 12.5 years. The final study included 169 men and 117 women (N = 286). The mean depth of invasion was 12.3 ± 11 mm (range, 1 to 69 mm). Mean lymph node density was 0.04 ± 0.1 (range, 0 to 0.81). There was a positive association between lymph node density and depth of tumor invasion (Pearson correlation coefficient, r = 0.21; P < .001). Tumors with perineural invasion had a statistically significant difference in mean lymph node density (0.074 for positive vs 0.024 for negative; P < .001). There also was a significant association in mean lymph node density with the presence of extracapsular spread (0.143 for positive and 0.010 for negative; P < .001).
Conclusions:
Statistically relevant positive linear relations among lymph node density, depth of invasion, perineural invasion, and extracapsular spread were identified. Lymph node density could have prognostic implications, because it is statistically correlated with other known prognostic features that lead to poor outcomes. Lymph node density could be an important feature to capture in future prospective trials. Pathology standards would be crucial in this endeavor.
