Higher Tumor Cellularity in Resected Pancreatic Ductal Adenocarcinoma Is a Negative Prognostic Indicator

Background/Aims: Desmoplasia is a prominent feature of pancreatic ductal adenocarcinoma (PDA). Stromal desmoplasia reflects the low cellularity that is characteristic of PDA, and it may play a role in PDA chemoresistance. In this retrospective study, we evaluated the relationship between tumor cellularity in resected PDA specimens and long-term patient outcomes. Methods: We retrospectively reviewed the data from 175 patients who underwent PDA resection between January 2010 and December 2015 at Seoul National University Bundang Hospital, and analyzed their clinicopathological features and the relationship between tumor cellularity (high vs low based on a cutoff of 30% cellularity) and patient outcomes. Results: The high-cellularity group had significantly shorter overall survival (OS) (18.7 months vs 26.6 months, p=0.006) and diseasefree survival (11.0 months vs 16.9 months, p=0.031) than the low-cellularity group. Multivariate analysis revealed that high tumor cellularity was an independent risk factor for poor OS (hazard ratio, 2.008; 95% confidence interval, 1.361 to 2.962; p<0.001). Adjuvant therapy improved OS in the low-cellularity group (16.3 months vs 41.3 months, p=0.001) but not in the high-cellularity group (15.9 months vs 24.4 months, p=0.107). Conclusions: Tumor cellularity in PDA specimens may be a prognostic and predictive biomarker that could aid in identifying patients who would benefit from adjuvant therapy for PDA.