A Novel T-Stage Classification System for Adrenocortical Carcinoma: Proposal from the U.S. Adrenocortical Carcinoma Study Group

Abstract

Abstract

Background:

The 7th AJCC T-stage system for adrenocortical carcinoma (ACC), based on size and extra-adrenal invasion, does not adequately stratify patients by survival. Lymphovascular invasion (LVI) is a known poor prognostic factor. We propose a novel T-stage system that incorporates LVI to better risk-stratify patients undergoing resection for ACC.

Methods:

Patients undergoing curative-intent resections for ACC from 1993 to 2014 at 13 institutions comprising the U.S. ACC group were included. Primary outcome was disease-specific survival (DSS).

Results:

A total of 149 of 265 patients with ACC were included for analysis. The current T-stage system failed to differentiate patients with T2 vs T3 disease (p = 0.10). Presence of LVI was associated with worse DSS vs no LVI (36 months vs 168 months; p = 0.001). After accounting for the individual components of the current T-stage system (size, extra-adrenal invasion), LVI remained a poor prognostic factor on multivariable analysis (HR: 2.14, 95% CI: 1.05–4.38, p = 0.04). LVI positivity further stratified patients with T2 and T3 disease (T2: 37 months vs median not reached; T3:36 vs 96 months; p = 0.03), but did not influence survival in patients with T1 or T4 disease. By incorporating LVI, a new T-stage classification system was created:[T1: ≤5 cm, (−)local invasion, (+/−)LVI; T2: >5 cm, (−)local invasion, (−)LVI OR any size, (+)local invasion, (−)LVI; T3: >5 cm, (−)local invasion, (+)LVI OR any size, (+)local invasion, (+)LVI;T4:any size, (+)adjacent organ invasion, (+/−)LVI]. Each progressive new T-stage group was associated with worse median DSS (T1: 167 months; T2: 96 months; T3: 37months; T4: 15 months; p < 0.001).

Conclusion:

Compared with the current T-stage system, the proposed T-stage system, which incorporates LVI, better differentiates T2 and T3 disease and accurately stratifies patients by DSS. If externally validated, this T-stage classification should be considered for future AJCC staging systems.

No competing financial interests exist.

Runtime of video: 8 mins 30 secs

Oral Presentation, SSO Annual Cancer Symposium March 2017, Seattle, WA.