Metrics of pN-staging in oral squamous cell carcinoma: An analysis of 1,905 patients

Prognostic Value of Lymph Node Yield, Lymph Node Density, and pN in Oral Cancer

OBJECTIVES

To investigate thresholds for lymph node yield (LNY), lymph node density (LND), and pN in patients with oral squamous cell carcinoma in relation to previous findings in the literature.

STUDY DESIGN

Retrospective register-based study.

SETTING

Copenhagen Oral Cavity Squamous Cell Carcinoma database.

METHODS

Appropriate thresholds for LNY, LND, and pN were determined by areas under the curve and subsequently subjected to multivariate analysis. Five-year overall survival and 3-year recurrence-free survival were determined by Kaplan-Meier survival curves.

RESULTS

In total, 413 patients diagnosed with oral squamous cell carcinoma were included. In the pN0 cohort, no superior/prognostic LNY cutoff values were detected. In the pN+ cohort, areas under the curve determined thresholds of LNY, LND, and pN to be 21 nodes, 5%, and 3 metastases, respectively. The 5-year overall survival was 52% for patients with LNY ≥21 vs 38% for patients with LNY <21 (hazard ratio [HR], 1.49; 95% CI, 1.05-2.11; P < .05), 60% for patients with LND ≤5% vs 38% for patients with LND >6% (HR, 1.63; 95% CI, 1.03-2.57; P < .05), and 43% for patients with pN <3 vs 26% for patients with pN ≥3 (HR, 1.40; 95% CI, 1.04-2.15; P < .05).

CONCLUSIONS

Increased nodal yield, decreased LND, and decreasing number of pN were associated with significantly improved survival outcomes. LNY might serve as a prognosticator of survival as well as a surgical quality indicator. LND may have implications as a tool in cancer staging and treatment planning.

Comparison of Different Staging Systems Applied to a Cohort of Patients With Oral Tongue and Floor of the Mouth Cancer

Purpose: The present work compares the effects produced by the application of the 7th edition of the tumor node metastasis (TNM) staging system (TNM7), 8th Edition (TNM8) with its two subsequent revisions, and pN-N+ classification on a cohort of patients with oral tongue and floor of the mouth cancer. Methods: A monocentric cohort of 148 patients was retrospectively analyzed. Patients were staged according to the TNM7, TNM8 and revisions, and pN-N+ classification. Stage migration was assessed and overall survival (OS) analyzed with the Kaplan-Meier method. The pT, pN, and stage stratification was evaluated with univariate and multivariate Cox regression and comparing adjacent categories with the log-rank method. Results: pT3-T4a categories showed significant differences in comparison to pT1-T2 for each staging metric employed in both uni- and multivariate analysis. When comparing adjacent pT categories, OS was significantly different only between pT2 and pT3 categories of the TNM8. Disproportionate patient distribution among pN categories was observed in the TNM8, and stratification was scarce. Conversely, in the pN-N+ classification the difference between pN2 and pN3a categories was significant. Only stage IVa reached statistical significance in TNM7, whereas stage III and above were significant in TNM8 and revisions in both uni- and multivariate analysis. However, no significant difference was noted comparing adjacent stages. Conclusion: The TNM8 pT classification differentiated low- from high-risk diseases. Nonetheless, it failed to separate pT1 from pT2 and pT3 from pT4a categories. Conversely, although TNM8 nodal staging was inaccurate, the number of metastatic lymph nodes was more valuable.

Limits and potential implementation of the present pN classification for oral squamous cell carcinoma

PURPOSE OF REVIEW

The purpose of this review is to highlight the most important changes in the eighth TNM classification system for oral squamous cell carcinomas compared with the seventh edition with focus on lymph node staging (pN). Nodal involvement is crucial when addressing prediction of survival, and staging must mirror the disease extension. pN classification will be evaluated with respect to lymph node yield (LNY), lymph node density (LND), and a recently proposed classification: pN-N+ reflecting positive regional lymph nodes (metastatic burden) and extra nodal extension.

RECENT FINDINGS

TNM8 was introduced in 2018, and the most noteworthy changes were depth of invasion (DOI) and extranodal extension (ENE). Recent studies indicate, that TNM8-related pN is not superior to TNM7 with respect to predicting survival. LNY and LND are biased with ecological interference fallacy, and currently not recommended in future iterations of TNM. In contrast, the pN-N+ classification has demonstrated improved survival prediction compared with TNM8.

SUMMARY

The recent findings support the inclusion of pN-N+, that is, metastatic burden and extranodal extension in future iterations of TNM.

Metavariables Resuming Host Immune Features and Nodal Involvement Are Associated with Oncological Outcomes in Oral Cavity Squamous Cell Carcinoma

Oral cavity squamous cell carcinoma (OSCC) is a common head and neck cancer characterized by a poor prognosis associated with locoregional or distant failure. Among the predictors of prognosis, a dense infiltration of adaptive immune cells is protective and associated with improved clinical outcomes. However, few tools are available to integrate immune contexture variables into clinical settings. By using digital microscopy analysis of a large retrospective OSCC cohort (n = 182), we explored the clinical significance of tumor-infiltrating CD8+ T-cells. To this end, CD8+ T-cells counts were combined with well-established clinical variables and peripheral blood immune cell parameters. Through variable clustering, five metavariables (MV) were obtained and included descriptors of nodal (NODALMV) and primary tumor (TUMORMV) involvement, the frequency of myeloid (MYELOIDMV) or lymphoid (LYMPHOIDMV) peripheral blood immune cell populations, and the density of tumor-infiltrating CD8+ T-cells (TI-CD8MV). The clinical relevance of the MV was evaluated in the multivariable survival models. The NODALMV was significantly associated with all tested outcomes (p < 0.001), the LYMPHOIDMV showed a significant association with the overall, disease-specific and distant recurrence-free survival (p < 0.05) and the MYELOIDMV with the locoregional control only (p < 0.001). Finally, TI-CD8MV was associated with distant recurrence-free survival (p = 0.029). Notably, the performance in terms of survival prediction of the combined effect of NODALMV and immune metavariables (LYMPHOIDMV, MYELOIDMV and TI-CD8MV) was superior to the TNM stage for most of the outcomes analyzed. These findings indicate that the analysis of the baseline host immune features are promising tools to complement clinical features, in stratifying the risk of recurrences.