Abstract
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.
Highlights
The American Joint Cancer Committee (AJCC)–Union for International Cancer Control (UICC) TNM staging system is a universally known tool that is designed to outline the loco-regional and distant extensions of a tumor and assign a prognosis
The AJCC/UICC staging manual standardized the measurement of depth of infiltration” (DOI), defined as the length of the plumb line drawn from the “horizon” of the basement membrane of the adjacent squamous mucosa to the deepest point of tumor infiltration [2]
This definition eliminates the variability related to the exophytic or ulcerated components of a tumor, even though it does not take into account other factors potentially distorting the DOI measurement such as extra-tumoral microscopic neoplastic foci, perineural invasion (PNI), lymphovascular invasion (LVI), or microscopically involved deep margins (R1) [8]
Summary
The American Joint Cancer Committee (AJCC)–Union for International Cancer Control (UICC) TNM staging system is a universally known tool that is designed to outline the loco-regional and distant extensions of a tumor and assign a prognosis. The AJCC/UICC staging manual standardized the measurement of DOI, defined as the length of the plumb line drawn from the “horizon” of the basement membrane of the adjacent squamous mucosa to the deepest point of tumor infiltration [2]. This definition eliminates the variability related to the exophytic or ulcerated components of a tumor, even though it does not take into account other factors potentially distorting the DOI measurement such as extra-tumoral (satellite) microscopic neoplastic foci, perineural invasion (PNI), lymphovascular invasion (LVI), or microscopically involved deep margins (R1) [8]. In the second, published on June 25, 2018 (hereafter, TNM8 June 2018), cancers larger than 4 cm and with DOI > 10 mm were moved into the pT4a category
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