Background:
To define the optimal treatment prognostic accuracy is mandatory. The 8th ed. of AJCC/UICC
TNM staging (TNM 2017) modifies staging of p16+ oropharyngeal squamous cell carcinomas
(OSCC). In p16+ OSCC, the N category (positive neck nodes, N+) is newly defined.
Methods:
Prognostic accuracy of TNM 2017 was retrospectively assessed in a cohort of 105 p16+
stage III-IVB OSCC patients with full information on extracapsular extension (ECE).
The Kaplan-Meier method and multivariate Cox proportional hazard regression were used
to assess ECE-dependent tumor-specific (TSS) and overall survival (OS).
Results:
92/105 (87.6%) OSCC were N+ (13 N0); 62/92 (67%) had ECE and 30/92 (33%) not. According
to TNM 2010, 11/92 (12%) were stage III, 78 (85%) IVA, and 3 (3%) IVB. TNM 2017 reclassified
36/92 (39.1%; III/IVA: 10/26) OSCC as stage I, 26 (28.3%; III/IVA/IVB: 1/24/1) as
II, and 30/92 (32.6%; IVA/IVB: 28/2) as III. The mean number of N+ in ECE+ vs. ECE-
(5.0, confidence interval [CI] 95% 3.8 – 6.4, median 4 vs. 2.4, CI 95% 1.8 – 2.9,
median 2) was different (p = 0.0007). According to Kaplan-Meier estimates, TNM 2017
failed discriminating exactly UICC I, II and III (mean OS in 54.5, 73.4, and 45.0;
median OS 64.7, not reached, and 41.1 months). ECE affected OS and TSS (p = 0.019,
p = 0.05), and OS in II was superior to I related to uneven distribution of N+ and
ECE. Cox proportional hazard models revealed ECE being an independent predictor for
impaired OS (hazard ratio, HR = 5.81, CI 95% 1.76 – 19.23; p = 0.004) and TSS (HR
= 5.71, CI 95% 1.03 – 31.25; p = 0.046).
Conclusion:
Survival of p16+ OSCC patients is affected by ECE that is a relevant prognostic factor
also in p16+ OSCC and should not be ignored but rather included in staging.
