Background: Palliative care (PC) improves outcomes for patients with advanced cancer, and current ASCO guidelines recommend early outpatient referral. However, recent data show that PC teams at many cancer centers see more inpatient consults than outpatient visits; the comparative impact of inpatient versus outpatient PC is not well-described. For this reason, we conducted a retrospective cohort study of hospitalized cancer patients to quantify exposure to inpatient/outpatient PC, and to describe associations between PC exposure and end-of-life (EOL) quality measures including hospice utilization, advance care planning (ACP), and intensity of care. Methods: We identified all patients admitted to one cancer center’s inpatient oncology unit during one fiscal year (10/1/2017-9/30/2018). Demographics, admission statistics, inpatient/outpatient PC visits, and EOL outcomes were abstracted from the electronic medical record. Decedents were identified through chart review and public obituaries. Results were summarized by descriptive statistics, and standard statistical tests were used to evaluate associations between PC exposure and EOL outcomes. Results: 842 patients were hospitalized in one year. 522 patients died by the study end-date of 10/1/2020 and were included in analysis. 50% of decedents had any PC exposure prior to death, but only 21% had an outpatient PC visit. Patients seen by PC were younger at time of death, (median: 67 vs 72 years; p <.001) and more likely to be female (52% vs 42%; p =.03). Compared to patients never seen by PC, patients with any PC exposure were significantly more likely to enroll in hospice (78% vs 44%; p <.0001), have do-not-resuscitate status (87% vs 55%; p <.0001), have scanned ACP documents (53% vs 31%; p <.0001), and die at home or inpatient hospice instead of in the hospital (67% vs 40%; p <.01). PC exposure was not associated with differences in 30-day re-admissions, systemic cancer therapy in the last 14 days of life, or intensive care (ICU) utilization in the last 30 days of life. Notably, PC exposure was associated with longer hospital length-of-stay (LOS) (8.4 vs 7.2 days), but this association was reversed for patients seen by outpatient PC versus all others (6.3 vs 8.2 days; p <.01). Patients seen by outpatient PC also had longer hospice LOS (46.5 vs 27.1 days; p <.01) and less EOL ICU use (6% vs 15%; p <.05) compared to all others. Conclusions: In this large retrospective study of hospitalized patients with cancer, PC exposure was associated with significant improvements in multiple EOL quality measures. The subset of patients seen by outpatient PC experienced additional benefits, including shorter hospital LOS, longer hospice LOS, and less EOL ICU utilization. These findings point to differential effects between inpatient and outpatient PC, underscoring the importance of early, longitudinal PC involvement.