Number of Metastatic Nodes a Predictor for Survival in Oral Cancer

Allen S. Ho, MD

The presence of metastatic lymph nodes was directly correlated with poorer survival in patients with oral cancer. Mortality risk rose continuously with the number of metastatic nodes without plateau, according to findings published in the Journal of Clinical Oncology.

Investigators found that the effect was most pronounced with up to 4 lymph nodes (hazard ratio [HR], 1.34; 95% CI, 1.29-1.39; P <.001). Extranodal extension (HR, 1.41; 95% CI, 1.20-1.65; P <.001) and lower neck involvement (HR, 1.16; 95% CI, 1.06-1.27; P <.001) were also predictors for increased mortality.

Citing the need for more precise staging metrics and treatment stratification, the investigators assessed the effect of quantitative metastatic nodal burden in a large population of patients with oral cavity cancer. Researchers selected oral cavity cancers because of their surgical treatment paradigm with more complete pathologic nodal data.

“Metastatic nodal burden is a central predictor of mortality in patients with oral cavity cancer, with each additional metastatic lymph node conferring escalated risk of mortality,” first author Allen S. Ho, MD, Department of Surgery, Cedars-Sinai Medical Center, and co-investigators wrote. “Classic factors such as lymph node size and contralateral nodal metastasis lack independent prognostic value when accounting for number of metastatic nodes.”

“Our data suggest that deeper integration of quantitative nodal burden could better calibrate the wide spectrum of risk that staging systems presently capture. Such adjustments would be a promising means to more effectively articulate patient prognosis, tailor clinical trial design, and ultimately advance clinical decision making,” added Ho et al.

Investigators at Cedars-Sinai Medical Center in Los Angeles examined data collected in the National Cancer Data Base on adult patients with oral cavity squamous cell carcinoma who underwent upfront surgical resection for curative intent (N = 14,554) from 2004 to 2013. Patients were segregated into node-negative (n = 7906) or node-positive (n = 6648) groups.

Median overall survival was 68.3 months (95% CI, 64.4-71.7), with a median follow-up of 46.5 months (95% CI, 45.7-47.3).

The mean number of lymph nodes examined was 32.1 (standard deviation [SD], ±17.4). Among patients with node-positive disease who had known data, the mean number of identified positive metastatic nodes was 3.3 (SD, ±4.3), 17.2% had lower neck (level 4-5) involvement, 45.2% demonstrated extranodal extension, and 13.3% harbored contralateral nodal involvement.

In univariate analysis, the number of metastatic lymph nodes strongly predicted poorer survival. Estimated 5-year OS was 65.3% for patients with no metastatic lymph nodes compared with 27.5% for patients with 4 metastatic nodes and 9.7% for those with 10 or more. After adjusting for potential confounders in a multivariable model, investigators found that the number of positive metastatic lymph nodes remained closely linked with OS (P <.001).

Investigators noted a change point when 4 metastatic nodes were identified. HR per metastatic lymph node increased steeply up to 4 metastatic LNs (HR, 1.34; 95% CI, 1.29-1.39; P <.001). Beyond that number, each additional metastatic lymph node increased the risk for death more slowly (HR, 1.03; 95% CI, 1.02-1.04; P <.001).

Investigators found an association between an increasing number of lymph nodes examined and improved OS in multivariable analyses (P <.001). A multivariable model with a three-knot restricted cubic spline function showed that, from a baseline of 10 lymph nodes examined, the risk for death declined continuously with each additional node harvested up to a change point at 35 nodes (HR, 0.98; 95% CI, 0.98-0.99; P <.001). There was no significant improvement in survival beyond that change point (HR, 1.00; 95% CI, 0.99-1.00; P = .126).

After adjusting for covariates, including positive metastatic lymph nodes and number of total nodes examined, both extranodal extension (HR, 1.41; 95% CI, 1.20-1.65; P <.001) and lower neck involvement (HR, 1.16; 95% CI, 1.06-1.27; P <.001) were independently associated with mortality risk. Lymph node size and contralateral lymph node involvement (N2c disease) had no significant impact on survival.

Ho AS, Kim S, Tighiouart M, et al. Metastatic lymph node burden and survival in oral cavity cancer [published online September 7, 2017]. J Clin Oncol. doi: 10.1200/JCO.2016. 71.1176.