Adjuvant chemoradiation to improve survival compared to adjuvant chemotherapy in selected patients with pancreatic cancer.

Abstract

330 Background: While surgery remains the only potential curative option for resectable pancreatic cancer, adjuvant therapy improves outcomes over surgery alone; however, adjuvant recommendations of chemotherapy vs chemoradiation remain controversial. We present outcomes comparing the two adjuvant treatments. Methods: In our single institution review, 343 patients (2000-2012) had pancreatoduodenectomy for pancreatic cancer. Medical oncology made adjuvant recommendations. Chemotherapy was gemcitabine or 5-FU and radiotherapy prescription was 45-54 Gy. Locoregional recurrences (LRR) were operative bed or regional nodal failures. Results: Median follow up and median survival (MS) for all patients was 17.5 and 19.5 mo respectively. 130 patients had resection alone (A), 84 had adjuvant chemotherapy (B), and 129 had adjuvant chemoradiation (C). MS for groups A, B, and C were 13, 23 and 26 mo respectively. Locoregional recurrence (LRR) was 60%, 63%, and 38% and distant failure was 64%, 65%, and 66% for groups A, B, and C respectively. Group C had significantly lower LRR compared to group B (p=0.01) however, survival between groups B and C was not statistically significant (p=0.23). Angiolymphatic invasion (ALI) and perineural invasion were correlated with LRR (p<0.01). Multivariable analysis showed LRR, laparoscopy, ALI, and the interaction term of LRR with surgical margin were significant predictors of survival (p<0.05). MS of patients with lymph node ratio (LNR) > 0.2 and LNR ≤ 0.2 was 18 and 27 mo respectively. Subgroup analysis showed survival advantages to adjuvant chemoradiation compared with adjuvant chemotherapy. R1 resections in groups B and C were 37% and 39% (p=ns) with MS of 16 vs 27 mo respectively (p=0.01). For patients with ≥ 8 LN dissected and LNR ≤ 0.2, MS was 24 vs 32 mo for groups B and C respectively (p=0.04). Conclusions: Adjuvant chemoradiation significantly decreases LRR in resected pancreatic cancer patients. Compared to adjuvant chemotherapy alone, adjuvant chemoradiation improved survival for patients with a 1) positive surgical margin and/or 2) LNR ≤ 0.2 with ≥ 8 LNs dissected.