Significance of pathologic response to preoperative therapy in pancreatic cancer

Background: Pathologic response to preoperative therapy is increasingly recognized as an important prognostic factor in solid tumors. The impact of pathologic response on survival in pancreatic adenocarcinoma is not well established. Methods: Data on 135 consecutive patients treated with chemoradiation followed by pancreatectomy for adenocarcinoma of the pancreatic head and/or body between July 1987 and May 2009 were reviewed. Histopathologic examination was performed in 107 patients to determine pathologic response, defined as minor (<50% fibrosis relative to residual neoplastic cells), partial (50-94% fibrosis), or major (95-100% fibrosis). Results: Minor, partial, and major pathologic response rates were 17% (n = 18), 64% (n = 68), and 19% (n = 21), including a 7% (n = 8) complete pathologic response rate. Pathologic response correlated with R0 resection (P = 0.019), negative lymph nodes (P = 0.006), and smaller tumor size (P = 0.001). Median survival rates by pathologic response were as follows: 17 months [95% confidence interval (CI), 0-36 months] for minor response, 20 months (95% CI, 17-23 months) for partial response, and 66 months (95% CI, 8-124 months) for major response (minor versus partial response, P = not significant; partial versus major response, P < 0.001). On multivariate analysis, major pathologic response was the only factor significantly associated with improved survival (P = 0.025; hazard ratio, 2.26). Conclusions: Major pathologic response to preoperative therapy occurs in a minority of patients with pancreatic adenocarcinoma and is independently associated with prolonged survival.