10 Background: Among individuals with advanced cancer (AC), frequent hospitalization is often at odds with patient preference and is increasingly viewed as a hallmark of poor quality care. Hospitalization contributes substantially to costs and regional spending variation in this population, but patterns and reasons are poorly described in the literature. Methods: California Cancer Registry data linked with hospital claims were used to quantify hospitalization in the year after diagnosis among individuals with AC [colorectal, pancreatic, prostate, breast, non-small cell lung cancer (NSCLC)] between 2009-2012 (n = 25, 032). Multi-state models and multilevel log-linear Poisson regression were used to model re-hospitalizations as a function of individual and hospital characteristics, accounting for the competing risk of mortality. Results: Among individuals with AC, 71% were hospitalized, 16% had at least 3 hospitalizations, and 64% of hospitalizations originated in the emergency department. Re-hospitalization rates were significantly higher for black, non-Hispanic (IRR 1.3; 95% CI: 1.1-1.4); Hispanic (IRR 1.1; 95% CI: 1.0-1.2); or Asian/Pacific Islander (IRR 1.1; 95% CI: 1.0-1.2) race/ethnicity vs. white, non-Hispanic; for public (IRR 1.4; 95% CI: 1.3-1.5) or no insurance (IRR 1.2; 95% CI: 1.0-1.5) vs. private; for lower SES quintiles (IRRs 1.1-1.3) vs. the highest; for 1 and 2 or more (IRR 1.1-1.6) comorbidities versus none, and for pancreatic cancer (IRR 2.1; 95% CI 1.9-2.2) and NSCLC (IRR 1.7; 95% CI 1.5-1.9) vs. colorectal cancer. Re-hospitalization rates were significantly lower after discharge from a hospital reporting an outpatient palliative care program (IRR 0.90; 95% CI 0.84-0.96). Conclusions: Individuals with AC experience a heavy burden of hospitalizations, many of which originate in the ED. Discharge from a hospital reporting an outpatient palliative care program appears to protect against re-hospitalization. Efforts to reduce hospitalization and provide care congruent with patient preferences might focus on improving access to outpatient palliative care, particularly among subgroups at greater risk, including racial/ethnic minority groups, those with lower SES, comorbidities and pancreatic or NSCLC.