Completion of Adjuvant Chemotherapy After Upfront Surgical Resection for Pancreatic Cancer Is Uncommon Yet Associated With Improved Survival

Abstract

Background: Multiple trials have demonstrated a survival benefit for adjuvant chemotherapy after resection of pancreatic adenocarcinoma. This study aimed to identify the rate for completion of adjuvant chemotherapy, factors associated with completion, and its impact on survival after surgical resection.

Methods: The Surveillance Epidemiology and End Results Medicare-linked data was used to identify patients who underwent upfront resection for pancreatic adenocarcinoma from 2004 to 2013. Billing codes were used to quantify receipt and completion of chemotherapy. Factors associated with completion of chemotherapy were identified using multivariable regression. Kaplan-Meier and Cox proportional-hazards modeling were used to examine survival.

Results: The inclusion criteria were met by 2440 patients. Of these patients, 65% received no adjuvant chemotherapy, 28% received incomplete therapy, and 7% completed chemotherapy. The factors associated with chemotherapy completion were nodal metastases and treatment at a National Cancer Institute-designated cancer center (p ≤ 0.05). Comorbidities decreased the odds of completion (p ≤ 0.05). The median overall survival (OS) was 14 months for the patients who received no adjuvant chemotherapy, 17 months for those who received incomplete adjuvant chemotherapy, and 22 months for those who completed adjuvant chemotherapy (p ≤ 0.05). More recent diagnosis, comorbidities, T stage, nodal metastases, and no adjuvant chemotherapy were associated with an increased hazard ratio for death (p ≤ 0.05). Evaluation of 15 or more nodes and completion of chemotherapy decreased the hazard ratio for death (p ≤ 0.05).

Conclusions: Only 7% of the Medicare patients who underwent upfront resection for pancreatic cancer completed adjuvant chemotherapy, yet completion of adjuvant chemotherapy was associated with improved OS. Completion of adjuvant chemotherapy should be the goal after upfront resection, but neoadjuvant chemotherapy may ensure that patients receive systemic chemotherapy.

FIG. 1

Rates for initiation and completion of chemotherapy by year of diagnosis. Numbers represent the percentage of patients with a diagnosis of pancreatic adenocarcinoma who underwent upfront surgical resection and subsequently received complete, incomplete, or no chemotherapy in the adjuvant setting (p = 0.49)

FIG. 2

Kaplan-Meier survival curve for all the patients in the SEER-Medicare-linked data who underwent upfront surgical resection for pancreatic adenocarcinoma from 2004 to 2013 stratified by receipt of adjuvant chemotherapy. The median overall survival was 14 months for the patients who received no adjuvant chemotherapy, 17 months for those who received incomplete adjuvant chemotherapy, and 22 months for those who completed adjuvant chemotherapy (p < 0.05)