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An Evaluation of the Eighth Edition of the American Joint Committee on Cancer (AJCC) Staging System for Retroperitoneal Sarcomas Using the National Cancer Data Base (NCDB)

Does Size Matter?

Fisher, Sarah B., MD, MS; Chiang, Yi-Ju, MSPH; Feig, Barry W., MD; Cormier, Janice N., MD, MPH; Hunt, Kelly K., MD; Torres, Keila E., MD; Roland, Christina L., MD, MS

American Journal of Clinical Oncology: February 2019 - Volume 42 - Issue 2 - p 160–165
doi: 10.1097/COC.0000000000000486
Original Articles: Soft Tissue

Objectives: 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: 5<x≤10 cm, T3: 10<x≤15 cm, T4: >15 cm). We evaluated the prognostic ability of the eighth edition using the National Cancer Database (NCDB).

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

Results: Of the 6427 patients identified, 9% had tumors ≤5 cm (n=580), 19.4% 5<x≤10 cm (n=1246), 20.2% 10<x≤15 cm (n=1298) and 47.4% >15 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 cm<x≤10 cm), and patients with larger tumors (stage IIIB, G2/3>10 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).

Conclusions: 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.

University of Texas MD Anderson Cancer Center, Department of Surgical Oncology, Houston, TX

Funded in part by K12 CA088084—Paul Calabresi Clinical Oncology Award and P30 CA016672—Cancer Center Support (CORE) Grant.

Presented as an oral presentation at the Society of Surgical Oncology Annual Cancer Symposium March 21-24, 2018, Chicago, IL.

The authors declare no conflicts of interest.

Reprints: Christina L. Roland, MD, MS, 1515 Holcombe Boulevard, Houston, TX 77030. E-mail: clroland@mdanderson.org.

Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.