Chemotherapy and supportive care practice patterns among older adults with metastatic pancreatic cancer.

e16373 Background: Metastatic pancreatic ductal adenocarcinoma (mPDAC) is a leading cause of cancer-related mortality in the U.S. Multi-agent chemotherapy regimens, such as FOLFIRINOX and gemcitabine/nab-paclitaxel (GnP), have varying degrees of toxicity, and treatment practice patterns in older adults remain understudied. We sought to describe changes in chemotherapy selection over time, factors associated with treatment selection, and the use of supportive care interventions to address treatment toxicities in older adults with mPDAC. Methods: Using the SEER population-based cancer registry linked with Medicare administrative claims (SEER-Medicare), we identified a cohort of individuals 66 years of age and older diagnosed with mPDAC who initiated infusion chemotherapy within 90 days of diagnosis between 2010-2019. Age and sex-standardized temporal trends in first-line treatment selection were quantified for the overall population and stratified by levels (robust, prefrail, frail) of the validated Kim claims frailty index. We used multinomial logistic regression to describe associations between patient factors (age, sex, comorbidity, and frailty) and first-line regimen received. We characterized time on first-line therapy and use of supportive care interventions (granulocyte colony stimulating factor (G-CSF), erythropoietin-stimulating agents (ESAs), and transfusions). Results: We identified a cohort of 7,073 adults (median age = 74 , 50.9% female). Overall, gemcitabine monotherapy (GM) was the predominant first-line treatment in 2010 at 80.6%, and fell to 17.4% in 2019, representing the third most-used regimen behind GnP (47.3%) and FOLFIRINOX (21.1%). Treatment varied by frailty; in 2019, FOLFIRINOX was used by 29.7% of those in the robust group, while it was the least common (8.2%) regimen in the frail group. Factors associated with receipt of GM instead of GnP included older age (≥80 vs. 66-69: odds ratio (OR) = 2.44), female sex (OR = 1.23), and increasing burdens of comorbidity (OR = 1.38), and frailty (OR = 2.36). Receipt of G-CSF was considerably higher for patients receiving first-line FOLFIRINOX (71.9%) compared with those receiving GnP (22.5%) and GM (13.1%). Receipt of ESAs (5.1%) and transfusions (7.4%) was lower for FOLFIRINOX than GnP (ESAs: 9.2%, transfusions: 11.5%) and GM (ESAs: 12.9%, transfusions: 12.4%). The median time on treatment before discontinuation, switching regimens, or death was about 55 days in both FOLFIRINOX and GnP-treated individuals. Conclusions: Chemotherapy use has evolved for older adults newly diagnosed with mPDAC, and we observed differences across levels of baseline frailty. Notably, the marked heterogeneity we found in selecting chemotherapy regimens and practice patterns in older adults merits ongoing investigation to help ensure patients receive treatment tailored to their unique geriatric needs.