Patterns of Adjuvant Chemotherapy Use and Association With Survival in Adults 80 Years and Older With Pancreatic Adenocarcinoma

Importance

Patients 80 years and older with pancreatic ductal adenocarcinoma (PDAC) have not consistently received treatments that have established benefits in younger older adults (aged 60-79 years), yet patients 80 years and older are increasingly being offered surgery. Whether adjuvant chemotherapy (AC) provides additional benefit among patients 80 years and older with PDAC following surgery is not well understood.

Objective

To describe patterns of AC use in patients 80 years and older following surgical resection of PDAC and to compare overall survival between patients who received AC and those who did not.

Design, Setting, and Participants

Retrospective cohort study among patients 80 years or older diagnosed with PDAC (stage I-III) between 2004 to 2016 who underwent a pancreaticoduodenectomy at hospitals across the US reporting to the National Cancer Database.

Exposures

AC vs no AC 90 days following diagnosis of PDAC.

Main Outcomes and Measures

The proportion of patients who received AC was assessed over the study period. Overall survival was compared between patients who received AC and those who did not using Kaplan-Meier estimates and multivariable Cox proportional hazards regression. A landmark analysis was performed to address immortal time bias. A propensity score analysis was performed to address indication bias. Subgroup analyses were conducted in node-negative, margin-negative, clinically complex, node-positive, and margin-positive cohorts.

Results

Between 2004 and 2016, 2569 patients 80 years and older (median [IQR] age, 82 [81-84] years; 1427 were women [55.5%]) underwent surgery for PDAC. Of these patients, 1217 (47.4%) received AC. Findings showed an 18.6% (95% CI, 8.0%-29.0%;P = .001) absolute increase in the use of AC among older adults who underwent a pancreaticoduodenectomy comparing rates in 2004 vs 2016. Receipt of AC was associated with a longer median survival (17.2 months; 95% CI, 16.1-19.0) compared with those who did not receive AC (12.7 months; 95% CI, 11.8-13.6). This association was consistent in propensity and subgroup analyses. In multivariable analysis, receipt of AC (hazard ratio [HR], 0.72; 95% CI, 0.65-0.79;P < .001), female sex (HR, 0.88; 95% CI, 0.80-0.96;P < .001), and surgery in the more recent time period (≥2011) (HR, 0.90; 95% CI, 0.82-0.99;P = .02) were associated with a decreased hazard of death. An increased hazard of death was associated with higher pathologic stage (stage II: HR, 1.68; 95% CI, 1.43-1.97;P < .001; stage III: HR, 2.39; 95% CI, 1.88-3.04;P < .001), positive surgical margins (HR, 1.49; 95% CI, 1.34-1.65;P < .001), length of stay greater than median (10 days) (HR, 1.17; 95% CI, 1.07-1.28;P < .001), and receipt of oncologic care at a nonacademic facilities (Community Cancer Program: HR, 1.20; 95% CI, 1.07-1.35;P < .001; Integrated Network Cancer Program: HR, 1.25; 95% CI, 1.07-1.46;P < .001).

Conclusions and Relevance

In this cohort study, the use of AC among patients who underwent resection for PDAC increased over the study period, yet it still was administered to fewer than 50% of patients. Receipt of AC was associated with a longer median survival.