Predictors of adjuvant treatment for pancreatic adenocarcinoma at the population level

Abstract

Background: In the present study, we aimed to describe, at the population level, patterns of adjuvant treatment use after curative-intent resection for pancreatic adenocarcinoma (pcc) and to identify independent predictors of adjuvant treatment use.

Methods: In this observational cohort study, patients undergoing pcc resection in the province of Ontario (population 13 million) during 2005-2010 were identified using the provincial cancer registry and were linked to administrative databases that include all treatments received and outcomes experienced in the province. Patients were defined as having received chemotherapy (ctx), chemoradiation (crt), or observation (obs). Clinicopathologic factors associated with the use of ctx, crt, or obs were identified by chi-square test. Logistic regression analyses were used to identify independent predictors of adjuvant treatment versus obs, and ctx versus crt.

Results: Of the 397 patients included, 75.3% received adjuvant treatment (27.2% crt, 48.1% ctx) and 24.7% received obs. Within a single-payer health care system with universal coverage of costs for ctx and crt, substantial variation by geographic region was observed. Although the likelihood of receiving adjuvant treatment increased from 2005 to 2010 (p = 0.002), multivariate analysis revealed widespread variation between the treating hospitals (p = 0.001), and even between high-volume hepatopancreatobiliary hospitals (p = 0.0006). Younger age, positive lymph nodes, and positive surgical resection margins predicted an increased likelihood of receiving adjuvant treatment. Among patients receiving adjuvant treatment, positive margins and a low comorbidity burden were associated with crt compared with ctx.

Conclusions: Interinstitutional medical practice variation contributes significantly to differential patterns in the rate of adjuvant treatment for pcc. Whether such variation is warranted or unwarranted requires further investigation.

Keywords: Pancreatic cancer; adjuvant chemotherapy; combined-modality therapy; medical practice variation; population analyses.

FIGURE 1

Distribution of patients not receiving adjuvant therapy, by geographic region of primary residence. Black circles denote designated hepatopancreatobiliary centres. LHIN = local health integration network.

FIGURE 2

Distribution of patients receiving adjuvant chemoradiation therapy, by geographic region of primary residence. Black circles denote designated hepatopancreatobiliary centres. LHIN = local health integration network.