An Evaluation of the Eighth Edition of the American Joint Committee on Cancer (AJCC) Staging System for...

Retroperitoneal sarcomas (RPS) are often large at diagnosis calling into question the seventh edition AJCC size classification of <5 cm (T1) or ≥5 cm (T2). The eighth edition expands T stage into 4 categories (T1: ≤5 cm, T2: 515 cm). We evaluated the prognostic ability of the eighth edition using the National Cancer Database (NCDB).

Patients with RPS treated between 1998 and 2011 were identified from the NCDB; overall survival (OS) was compared.

Of the 6427 patients identified, 9% had tumors ≤5 cm (n=580), 19.4% 515 cm (n=3045). With the eighth edition, stage II patients (G2/3 ≤5 cm) have a similar OS to stage IIIA patients (G2/3 5 cm10 cm) show a decrease in OS. Tumor size as a continuous variable had a modest effect on survival (HR, 1.004; P=0.04). On multivariate analysis, higher T-stage was associated with decreased OS (T4 HR, 1.3; P<0.001) but high grade and incomplete resection (R2) were stronger prognostic factors. The c-index for both editions were similar (80.13 eighth vs. 80.08 seventh).

The eighth edition AJCC staging system for retroperitoneal sarcoma incorporates larger tumor size parameters that better characterize most patients, but tumor size alone is only a modest predictor of outcome.