Abstract and Introduction
Abstract
Background: A recent revision of the American Joint Committee on Cancer (AJCC) staging for gallbladder cancer (6th Edition) involved some major changes. Most notably, T2N0M0 tumors were moved from stage II to stage IB; T3N1M0 disease was moved from stage III to stage IIB; and T4NxM0 (x = any) tumors were moved from stage IVA to stage III.
Methods: In order to determine if these changes were justified by data, an analysis of the 10,705 cases of gallbladder cancer collected between 1989 and 1996 in the NCDB was performed. All patients had >5 year follow-up.
Results: The staging according to the 6th Edition provided no discrimination between stage III and IV. Five-year survivals for stage IIA, IIB, III, and IV (6th Edition) were 7%, 9%, 3%, 2% respectively. The data from the National Cancer Database (NCDB) were used to derive a proposed new staging system that builds upon Edition 5 and had improved discrimination of stage groups over previous editions.
Conclusions: Changes in staging systems should be justified by data. Multicenter databases, including the NCDB, represent important resources for verification of evidence-based staging systems.
Introduction
Staging is integral both to selection of cancer treatments as well as to the evaluation of effectiveness of cancer therapies. The prognostic information provided allows distinction of patients at risk for poor outcome to justify toxic therapies. A reasoned and accepted classification system also allows for comparison of results from different institutions and eras. Additionally, staging allows for selection of patients for clinical trials and appropriate stratification. Stage-related assessment of outcome allows confident evaluation of effectiveness of new therapies. In these regards, the American Joint Commission on Cancer (AJCC) staging system has been invaluable in the care and study of many cancer patients.
Gallbladder cancer is a relatively rare cancer that affects only approximately 2500 patients yearly in the United States. This cancer is much more common in Japan, India, and Chile. Much of our knowledge in natural history and, consequently, in staging for this cancer is derived from experiences from these other populations, although it is not yet proven that the genetics or cellular biology of tumors from these other populations are the same as our North American patients. Because of the rarity of this cancer in North America, only a few centers have accumulated sufficient experience to definitively report on outcome. In the current study, we seek to validate staging for this disease using data from the National Cancer Database (NCDB). This database collects cancer data from approved cancer centers across the nation with the goal of allowing cooperative evaluation of cancer care and outcome. Using data from over 10,000 cases of gallbladder cancer, we critically examined the current staging and propose a new schema justified by these data.