Comparison of the 8th Edition American Joint Committee on Cancer (AJCC) nodal staging system in cutaneous and oral squamous cell cancer of the head and neck

Background:

The American Joint Committee on Cancer (AJCC) uses the same nodal staging system for cutaneous and mucosal squamous cell carcinoma of the head and neck in its 8th edition (AJCC 8) despite differences in the etiology, risk factors and clinical behavior of both diseases. This study aims to evaluate the performance of the AJCC 8 nodal staging system.

Methods:

Patients with metastatic cSCC (N = 382) and oSCC (N = 325) were identified from a prospective database (year 1987 – 2016). Multivariable analysis was performed using Cox proportional hazards competing risk model adjusting for the effect of adjuvant radiotherapy. To assess staging system performance an explained variation measure (Proportion of explained variation, PVE) as well as a discrimination measure (Harrell's concordance index, C-index) were used.

Results:

The inclusion of extranodal extension (ENE) in AJCC 8 has increased the proportion of patients in the N3b category (48.7% in cSCC, 40.3% in oSCC). AJCC 8 stratifies poorly with regards to risk of death from cSCC and oSCC and shows limited monotonicity of the nodal categories. The estimates for model performance reveal modest predictive capacity for overall survival (OS) and disease specific survival (DSS) in oSCC (Harrell's C of 0.66 in both) and weak predictive capacity in cSCC (Harrell's C of 0.58 and 0.61, respectively).

Conclusions:

The AJCC 8 nodal staging system performs poorly in terms of stratifying survival by N category in cSCC. The data indicate that cSCC merits an independent nodal staging system that takes its biology and anatomy of its nodal basin into consideration.

Publication History

Publication Date:
18 April 2018 (online)