1958P - Head and neck soft tissue sarcoma: Evaluation of the 8th AJCC as a prognostic tool for patients treated with curative intent in a multidisciplinary cancer center

Background

HN-STS is a challenging disease due to its diverse clinical presentation. In an attempt to refine the prognostication of these pts, the AJCC in its 8th edition proposed a new dedicated T staging group based on cutoffs of 2 and 4 cm for classifying T1, T2 and T3, and surrounding tissue invasion as T4, as opposed to the dichotomic T1-T2 5cm cutoff adopted by the 7th AJCC.

Methods

This is a retrospective study of pts diagnosed with nonmetastatic HN-STS treated with curative intent in a single tertiary hospital, approved by the institutional ethical review committee. The aim was to compare the 8th AJCC T staging to the previous classification as a prognostic tool for HN-STS, added to other variables such as age, histological subtype, grade and regional lymph node metastasis (LNM). AJCC 7th and 8th have been compared regarding T staging with Cohen’s kappa coefficient (KC) using inter-rater agreement analysis. The Kaplan-Meier estimator was used to calculate median survival time and differences in time-to-event outcomes were assessed using the log-rank test. Cox proportional hazard model was used to assess the effect of features in overall survival (OS).

Results

From 1997 to 2000, 135 pts were identified in institutional archives. Sarcoma NOS (N=50) and Leiomyosarcoma (N=17) were the most common histologic subtypes, as well as high-grade tumors (N=85). KC of inter-rater agreement was 0.46, statistically significant (p=0.03), indicating poor agreement between both T staging systems. Regarding OS, AJCC 7th (T1 and T2) and 8th (T1, T2, T3 and T4) T size stratification was not statistically different (P=0.42 and P=0.27, respectively). High-grade (71.4% vs 93.6%, P=0.005) and regional LNM (31.3% vs 81.4%, P=0.008) had worse 5-year OS in Cox multivariate analysis. Pts with tumor size>4cm or local invasion, high grade and LNM had 2.30, 7.11 and 4.37-fold increased risk of death respectively.

Conclusions

In our series, neither 7th nor 8th AJCC T size classifications adequately stratified prognostic groups or correlated survival for HN-STS pts. The 8th AJCC T4, the high-grade tumors and regional LNM demonstrated significant worse prognostic impact in pts harboring HN-STS.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.