Significance of pathologic response to preoperative therapy in pancreatic cancer.

Abstract

4067 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 gemcitabine or 5-fluorouracil-based chemoradiation followed by pancreatectomy for adenocarcinoma of the pancreatic head and/or body between July 1987 and May 2009 were reviewed. Prospective histopathologic examination was performed in 108 patients to determine pathologic response, defined as minor (<50% fibrosis relative to residual neoplastic cells), partial (50- 94% fibrosis), and major (95-100% fibrosis). Results: Minor, partial, and major pathologic response rates were 17% (n=18), 64% (n=69), and 19% (n=21), including a 7% (n=8) complete pathologic response rate. Pathologic response correlated with R0 resection (p=0.019), positive lymph nodes (p=0.006), and tumor size (p=0.001, Table). Median survival rates by pathologic response were as follows: 10 months (95% confidence interval [CI], 0-25 months) minor response, 14 months (95% CI, 11-17 months) partial response, and 51 months (95% CI, 29-73 months) major response (minor vs. partial response, p=not significant; partial vs. major response, p=0.011). Multivariate analysis revealed that major pathologic response (p=.029; hazard ratio [HR], 2.51) and R0 resection (p=0.001; HR, 2.33) were independent predictors of survival. Conclusions: Major pathologic response to preoperative therapy occurs in a minority of patients with pancreatic adenocarcinoma and is independently associated with prolonged survival. Pathologic response R0 resection, n (%) Positive lymph nodes, n (%) Median tumor size (range), cm Minor, n = 18 12 (67%) 4 (22%) 3.5 (1-5.5) Partial, n = 69 36 (52%) 24 (35%) 2.5 (1-5.7) Major, n = 21 18 (86%) 0 0.3 (0-6.5) No significant financial relationships to disclose.