How well do we communicate risk? An evaluation of AJCC version 6 and 7 staging systems for soft tissue sarcomas.

Abstract

10001 Background: Cancer staging systems allow physicians to communicate risks of a particular clinical situation with one another and with patients. Few data have been presented to support the update of a commonly employed staging system for soft tissue sarcoma (STS). We examined American Joint Committee on Cancer (AJCC) versions 6 (2002) and 7 (2010) staging systems for patients with primary STS using a single institution clinically annotated prospective database. Methods: Subsets of the prospectively collected Memorial Sloan-Kettering Cancer Center STS database of 8647 patients from 1982 to 2010 were examined with respect to criteria of the AJCC versions 6 and 7 staging systems. Results: Tumor size does not appear to be adequately addressed in version 6 or 7. Relapse-free survival was statistically worse for increasing size of primary STS <5, 5-10, 10-15, and >15 cm; in comparison, overall survival decreased over three size categories (<5, 5-10, >10 cm). Tumor depth, a statistically significant factor in patient outcomes that is included in version 6, is functionally omitted in version 7. Patients with node involvement without other metastases fare statistically worse than patients with large, high grade tumors without nodal metastasis, as shown previously. Version 6 and 7 criteria do not address effects of primary anatomic site and histology, even for tumors with same FNCLCC grade. Sarcoma subtypes defined after publication of FNCLCC criteria are difficult to incorporate into existing guidelines. Conclusions: Improved prognostication of STS outcomes is better achieved by staging according to anatomic primary site, depth, and a larger number of size categories. Histology-specific nomograms improve prognostic accuracy, such as those for liposarcoma, GIST, or rhabdomyosarcoma. Staging accuracy increases at the cost of portability and simplicity. The increasing difficulties with use of a single STS staging system highlight the potential benefit of newer techniques, such as patient-specific nomograms or Bayesian networks. Staging systems will require significant modifications to incorporate increasingly sophisticated molecular diagnostics.