Validation of the 6th edition AJCC pancreatic cancer staging system

BACKGROUND: With the development of stage-specific treatments for pancreatic cancer, controversies exist concerning optimal clinical and pathologic staging. The most recent edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual 6(th) Edition included some notable modifications. In anticipation of the 7(th) edition's publication, the authors evaluated the predictive ability of the current pancreatic adenocarcinoma staging system. METHODS: By using the National Cancer Data Base (1992-1998), 121,713 patients were identified with pancreatic adenocarcinoma. All patients were restaged by AJCC 6(th) edition guidelines. Stage-specific overall survival was estimated by using the Kaplan-Meier method and compared with log-rank tests. Concordance indices were calculated to evaluate the discriminatory power of the staging system. Cox modeling was used to determine the relative impact of T, N, and M classification on survival. RESULTS: For all patients, there was 5-year survival discrimination by stage (P < .0001). For patients who underwent pancreatectomy, stage predicted 5-year survival: stage IA, 31.4%; IB, 27.2%; IIA, 15.7%; IIB, 7.7%; III, 6.8%; IV, 2.8% (P < .0001). The concordance index for the staging system was 0.631 for all patients, 0.613 for those who underwent pancreatectomy, and 0.596 for patients who did not undergo resection. In patients who underwent pancreatectomy, tumor size, nodal status, and distant metastases were independent predictors of survival (P < .0001). CONCLUSIONS: This is the first large-scale validation of the pancreatic cancer staging system. AJCC 6(th) edition staging guidelines are accurate with respect to survival. Further investigation is needed to integrate new molecular and biochemical markers into the staging scheme.