E230: Impact of initial resectability and neoadjuvant chemotherapy on overall survival for pancreatic adenocarcinoma

A retrospective review was performed for patients who underwent PDAC resection between January 2010 and December 2020 at a tertiary hospital.  OS was assessed by the Kaplan Meier method and univariate cox models.  Survival was calculated based on the date of initial tumor diagnosis. 

Results:

In this cohort, 356 patients underwent PDAC resection.  Neoadjuvant chemotherapy was administered to 129 patients (36%) while 227 patients (64%) went straight to resection. 254 patients (71%) were classified as initially resectable, with a higher percentage going upfront surgery (P< 0.001).  Adjuvant chemotherapy was administered in 64% of patients.  Median OS was not significantly different between patients who underwent neoadjuvant chemotherapy (P=0.59) or based on initial resectability (P=0.25) in this cohort.  By univariate cox analysis, factors associated with worse OS included advanced age, Stage 3 disease, positive lymph nodes, positive margins, T3 or T4 tumors, large tumor size, poor grade, perineural invasion, and lymphovascular invasion (P< 0.01, all) while  adjuvant chemotherapy (P=0.02) was associated with improved OS.  By multivariate analysis, only positive lymph nodes (P=0.006) and T3/T4 tumors (P=0.008)  remained independent predictors of poor survival while adjuvant chemotherapy was associated with improved survival (P< 0.001).  When stratified by initial resectability and neoadjuvant chemotherapy, the highest median OS was seen in resectable patients who received neoadjuvant treatment (68.8 months) while the worst was in resectable patients who did not receive neoadjuvant chemotherapy (22 months) (Figure 1).  Initially borderline resectable or locally advanced patients who underwent neoadjuvant chemotherapy had similar survival to resectable patients that did not (32.7 vs. 31 months). 

Conclusions: In a selected retrospective cohort, neither neoadjuvant chemotherapy or initial resectability was associated with improved median OS indicating the impact of histopathologic and biologic factors.  Neoadjuvant chemotherapy appears to improve survival in resectable patients and also plays an important role in converting patients to resectable disease.