Histologic characteristics enhance predictive value of American Joint Committee on Cancer staging in resectable pancreas cancer

Background: American Joint Committee on Cancer (AJCC) anatomic stage group is considered relatively nondiscriminatory for predicting differences in survival after pancreatectomy for ductal adenocarcinoma, a perception confirmed in the authors' patients and by other reports. The authors' aim was to investigate the potential for improving the predictive value of AJCC staging by incorporating individually predictive histologic features into AJCC tumor-node-metastasis classification of anatomic extent, and determine the simplest combination of tumor characteristics predicting survival.

Methods: The authors determined survival of 137 patients who underwent pancreatectomy for ductal adenocarcinoma with curative intent (stage Groups IA-IIB) at Moffitt Cancer Center during the last 2 decades using data obtained from medical record review, the Moffitt Cancer Registry, and the Social Security Death Index. Histologic characteristics were confirmed by expert review.

Results: Median survival was 21.2 months after pancreatectomy with a 3-year disease-specific survival of 36%. Univariate Kaplan-Meier analysis and multivariate Cox proportional hazard modeling found worse survival with local extrapancreatic extension, poorly differentiated histology, and lymphatic invasion within tumor (P<.05). Survival was not worse with nodal metastases, microscopically positive resection margins, and perineural or venous invasion, nor was survival better with cancer arising from an intraductal papillary mucinous neoplasm. Kaplan-Meier estimates for different variable combinations showed prognosis was best for well- or moderately differentiated tumors without lymphatic invasion and confined to the pancreas (9.9 years median survival), worst for poorly differentiated tumors with lymphatic invasion and local extension beyond the pancreas (8.5 months median survival), and intermediate for well- or moderately differentiated tumors with either lymphatic invasion or local extension beyond the pancreas (21.2 months median survival).

Conclusions: A simple combination of tumor differentiation, lymphatic invasion within the tumor, and local extrapancreatic extension predicts survival after pancreatectomy for ductal adenocarcinoma.