Predictors of two-year survival in patients receiving chemotherapy for metastatic pancreatic ductal adenocarcinoma (mPDAC): A single-center retrospective cohort study.

Abstract

666 Background: Median survival in patients with mPDAC is typically between 6 and 11 months, and survival of more than two years is uncommon. Given the high mortality of mPDAC, identifying prognostically favorable characteristics could improve risk stratification and better inform early goals of care discussions. We conducted an exploratory analysis to identify characteristics associated with survival of ≥2 years among patients with mPDAC. Methods: We conducted a retrospective study of patients receiving chemotherapy for mPDAC within a single health system from 2015-2024. We abstracted patient demographic and clinical characteristics, baseline laboratory values, and overall survival (OS, defined as days between the first chemotherapy administration for mPDAC and date of death). We compared the distribution of demographic and clinical characteristics and baseline laboratory values across cohorts of ≥2 vs. <2-year overall survival, using chi-square tests for categorical variables and Wilcoxon rank-sum tests for continuous variables. Patients censored prior to 2 years were retained and analyzed as <2-year survivors. Results: We identified 287 patients who started chemotherapy for metastatic pancreatic cancer during the study period (FOLFIRINOX, 40%; gemcitabine + nab-paclitaxel, 49%; other, 11%). The median age was 69 years, and 45% were female. KRAS mutations were present in 110 of 112 patients (98%) with available somatic genomic data. Median survival among all patients was 7.0 months (IQR 3.4, 14.0), and 33 patients (12%) were confirmed ≥2-year survivors. Patients with a history of pancreatectomy prior to diagnosis of metastasis had a 2.7 times greater odds of being 2-year survivors (95% CI 1.2-5.8, P=0.01). There was no significant difference between the 2-year survivors and reference patients with respect to age, sex, primary tumor subsite, body mass index, initial chemotherapy regimen, or treatment era. Baseline laboratory values associated with survival of ≥2 years included higher albumin (median 4.1 vs. 3.8 g/dL, P<0.01) and lower neutrophil count (median 3.5 vs 5.3 K/mm 3 , P<0.01), neutrophil-to-lymphocyte ratio (median 2.8 vs 4.6, P<0.01), platelet count (median 199 vs 229 K/mm 3 , P=0.03), bilirubin (75 th percentile 0.6 vs 1.0 mg/dL, P=0.02), and CA19-9 (median 229 vs 1154 units/mL, P=0.01). Lymphocyte count, hematocrit, sodium, AST, and ALT were not significantly associated with 2-year survival (P>0.05 for all). Conclusions: Two-year survival was observed in 12% of patients receiving chemotherapy for mPDAC. Prior history of pancreatectomy and several baseline laboratory measures of inflammation and disease burden were significantly associated with increased likelihood of 2-year survival. Age and initial chemotherapy regimen were not associated with 2-year survival.