Impact of tumor grade on pancreatic cancer prognosis: validation of a novel TNMG staging system.
BACKGROUND
Pancreatic ductal adenocarcinoma (PDAC) patients demonstrate highly variable survival within each stage of the American Joint Committee on Cancer (AJCC) staging system. We hypothesize that tumor grade is partly responsible for this variation. Recently our group developed a novel tumor, node, metastasis, grade (TNMG) classification system utilizing Surveillance Epidemiology and End Results (SEER) data in which the presence of high tumor grade results in advancement to the next higher AJCC stage. This study's objective was to validate this TNMG staging system utilizing single-institution data.


METHODS
All patients with PDAC who underwent resection at UCLA between 1990 and 2009 were identified. Clinicopathologic data reviewed included age, sex, node status, tumor size, grade, and stage. Grade was redefined as a dichotomous variable. The impact of grade on survival was assessed by Cox regression analysis. Disease was restaged into the TNMG system and compared to the AJCC staging system.


RESULTS
We identified 256 patients who underwent resection for PDAC. Patients with low-grade tumors experienced a 13-month improvement in median survival compared to those with high-grade tumors. On multivariate analysis, tumor grade was the strongest predictor of survival with a hazard ratio of 2.02 (p = 0.0005). Restaging disease according to the novel TNMG staging system resulted in improved survival discrimination between stages compared to the current AJCC system.


CONCLUSIONS
We were able to demonstrate that grade is one of the strongest independent prognostic factors in PDAC. Restaging with our novel TNMG system demonstrated improved prognostication. This system offers an effective and convenient way of adding grade to the current AJCC staging system.
Department of Surgery, Greater Los Angeles VA Healthcare System, Los Angeles, CA, USA.
Matthew M
MM
Rochefort
Jacob S
JS
Ankeny
Brian E
BE
Kadera
Graham W
GW
Donald
William
W
Isacoff
Zev A
ZA
Wainberg
O Joe
OJ
Hines
Timothy R
TR
Donahue
Howard A
HA
Reber
James S
JS
Tomlinson
D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D000368:Aged; D021441:Carcinoma, Pancreatic Ductal / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D060787:Neoplasm Grading; D009367:Neoplasm Staging / Q000592:standards*; D010190:Pancreatic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D011446:Prospective Studies; D015996:Survival Rate; D054928:Validation Studies as Topic