Total Number of Lymph Nodes in Neck Dissection and Its Relation to Cancer-Positive Lymph Nodes as a Prognostic Indicator in Aerodigestive Tract Cancers: A Multi-Center Study

Abstract

Objectives Few studies have been conducted on the total number of lymph nodes (LNs) in neck dissection and the lymph node ratio (LNR; number of positive lymph nodes divided by number of excised lymph nodes), or their potential use as a prognostic indicator for cancers of the upper aerodigestive tract (UADT) and its treatment. We aimed to measure the number of lymph nodes dissected and the LNR to assess their prognostic value for cancers of the UADT, as well as their effect on overall survival and disease-free survival. Methods We performed a retrospective study of patients diagnosed with cancer of the UADT who underwent neck dissection as the primary or secondary modality of their treatment plan at King Abdulaziz University Hospital and the National Guard Hospital, Jeddah, Saudi Arabia. Data were collected through medical records and analyzed to assess prognosis and calculate survival rates in relation to the number of lymph nodes and LNR. Results A total of 121 patients were included: 14 women (11.57%) and 107 men (88.43%). The median age was 60 years and the mean follow-up period was 2.7 years. Of the malignancies, 44.63% were of the oral tongue and 35.54% were laryngeal. A median of 38 lymph nodes were dissected during neck dissections. The distribution of the individual LNRs was characterized by mean values. A mean LNR of 0.04 was considered the cutoff value, an LNR of > 0.04 a high LNR, and an LNR of < 0.04 a low LNR. Kaplan-Meier survival estimates for the cohort showed a three-year overall survival rate of 88% (95% confidence interval [CI]: 77% to 94%) for patients with a low LNR, but 71% (95% CI: 47% to 85%) for patients with a high LNR, which was statistically significant. A similar significant decreasing trend persisted at the four-year follow-up, where the disease-free survival rate was 73% (95% CI: 61% to 82%) for patients with a low LNR compared with 56% (95% CI: 35% to 72%) for patients with a high LNR. Conclusion The number of excised lymph nodes in neck dissections and the LNR might be a good prognostic indicator for overall survival and disease-free survival in patients with cancers of the UADT and may serve as a valuable tool in deciding on different treatment plans.

Keywords: aerodigestive; dissection; lymph; neck; node; ratio.

Figure 1. Box Plot Showing the Distribution of the log10 Lymph Node Ratio (LNR) Between Genders

Figure 2. Box Plot Showing the Number of Lymph Nodes (LN) Increasing With Staging

Figure 3. Kaplan–Meier Survival Estimates Showing Three-Year Overall Survival

LNR: lymph node ratio

Figure 4. Kaplan–Meier Survival Estimates Showing Four-Year Disease-Free Survival

LNR: lymph node ratio