Background: Use of chemotherapy at end-of-life (EOL) is associated with adverse quality of life, higher costs, increased hospitalizations (HL), emergency department (ED), and intensive care unit (ICU) utilization and lower hospice (HP) use. While EOL chemotherapy use has declined in recent years, EOL immunotherapy use has increased. It is unknown how the trend of increased immunotherapy use at the EOL is associated with healthcare utilization. We evaluated the association between types of systemic anticancer therapy (SACT) within 30 days of death and hospitalizations, emergency department, intensive care unit, and hospice use. Methods: We identified patients in the SEER-Medicare database with a diagnosis date of 2005-2019 and death date of 2015-2020 with the following cancers: breast, colorectal, lung, prostate, bladder, cervix, kidney, leukemia, liver, lymphoma, myeloma, ovarian, pancreas, skin, and uterine. EOL SACT was defined as SACT received within 30 days of death, categorized as combination chemo-immunotherapy, immunotherapy, and chemotherapy. We analyzed associations between EOL SACT use (overall and by type), and healthcare utilization in the last 30-days of life (ED, HL, ICU, and HP) with chi-square tests and multivariable regression, controlling for sociodemographic and cancer covariates. Results: Of 499,607 beneficiaries, 37,595 (7.5%) received SACT within 30 days of death. Compared to no EOL SACT, any SACT use was associated with higher ED [75.5% vs 50.8%], HL [71.0% vs 48.7%] and ICU (35.7% vs 23.3%) and lower HP enrollment (46.1% vs 59.3%) and number of days in HP (2.4 vs 6.5 days) (all p<0.001, table). After adjusting for covariates, patients with EOL SACT were more likely to have HL (odds ratio [OR], 2.43; 95% confidence interval [CI], 2.38-2.49), ED visits (OR, 2.87; 95% CI, 2.80-2.94), and ICU stay (OR, 1.66; 95% CI, 1.62-1.70), and less likely to receive HP care (OR, 0.62; 95% CI: 0.61-0.64)-compared to no SACT use; All subtypes of EOL SACT were significantly more likely to have ED, HL, and ICU use and less likely to use HP than those with No EOL SACT (p-values <0.001). Conclusions: All types SACT within 30 days of death were associated increased healthcare use compared with no EOL SACT, with combination chemo-immunotherapy having the highest ED, hospitalizations and ICU use and lowest hospice enrollment and duration.

*P-values for statistical difference between each individual SACT subgroup and No SACT and Any SACT and No SACT group.