ONCOLOGIC OUTCOMES OF CYST-ASSOCIATED VS. CLASSICAL PANCREATIC DUCTAL ADENOCARCINOMA
Timothy E. Newhook*, Michael P. Kim, Yi-Ju Chiang, Ching-Wei Tzeng, Naruhiko Ikoma, Jean-Nicolas Vauthey, Thomas Aloia, Jeffrey E. Lee, Matthew Katz, Hop Tran Cao
Surgical Oncology, MD Anderson Cancer Center, Missouri City, TX
Background: Differences between mucinous cyst-associated pancreatic cancer (CA-PC) and classic pancreatic ductal adenocarcinoma (PDAC) are poorly understood and mostly derived from small series. We sought to characterize contemporary presentations, treatment patterns, and outcomes for patients with CA-PC vs. PDAC in a large national dataset.
Methods: This is a retrospective cohort study of patients designated as CA-PC vs. PDAC from the National Cancer Data Base (2004-2016). Survival was estimated using the Kaplan-Meier method. Association between tumor type and overall mortality death was evaluated using multivariable regression analysis.
Results: Among 211,016 evaluable patients, 4.7% (n=9,920) had CA-PC and 95.3% (n=201,096) had PDAC. Patient demographics were not clinically different. Compared to PDAC, CA-PC were more likely to be diagnosed at an earlier stage (cT0/T1 11.5% vs. 5.0%, p<0.001) and with smaller tumors (size ≤2 cm, 12.3% vs. 8.2%, p<0.001). CA-PC patients were more likely to undergo resection (40.5% vs. 24.3%, p<0.001) and less likely to receive adjuvant chemotherapy (46.0% vs. 58.6%, p<0.001) or radiotherapy (15.0% vs. 20.8%, p<0.001). Among resected patients, those with CA-PC were more likely to have early-stage disease (AJCC 8 Stage 0-II 81.9% vs. 65.1%, p<0.001), no nodal involvement (65.9% vs. 32.5%, p<0.001), and R0 resection (81.0% vs. 73.1%, p<0.001). When only surgical patients were considered, median overall survival (OS) was longer for CA-PC vs. PDAC (57.3 vs. 19.4 months, p<0.001; Fig. 1), and on multivariate analysis, CA-PC was associated with a 50% reduction in risk of death compared to PDAC (HR 0.49, 95% CI 0.47-0.51, p<0.001).
Conclusions: In this national study comparing CA-PC with PDAC, CA-PC was associated with improved OS following pancreatectomy when compared to PDAC, even after adjustment for patient demographics, disease stage, and non-surgical oncologic treatments. Our findings of more favorable outcomes and potentially greater post-resection benefits for CA-PC may be informative in the shared decision-making of CA-PC patients and their clinicians.
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