ImportanceLittle is known about the nature of change in goals of care (GOC) over time among adolescents and younger adult (AYA) patients aged 12 to 39 years with cancer near the end of life. Understanding how GOC evolve may guide clinicians in supporting AYA patients in making end-of-life decisions.ObjectiveTo assess frequency, timing, and evolution of documented GOC among AYA patients with cancer in the last 90 days of life.Design, Setting, and ParticipantsThis cross-sectional study included a retrospective review of medical records from the Dana-Farber Cancer Institute, Kaiser Permanente Northern California, and Kaiser Permanente Southern California of AYA patients with cancer who were 12 to 39 years of age at death and who died between January 1, 2003, and December 31, 2019. Data were analyzed from July 1, 2023, through April 30, 2024.ExposuresStage IV cancer or stage I-III cancer with new metastasis or recurrence.Main Outcome and MeasuresThe primary outcome was documented GOC discussions, categorized by timing before death as initial (>60 days), middle (31-60 days), or late (≤30 days). Goals were classified as palliative, nonpalliative, undecided, or not discussed. Subgroup analysis according to race and ethnicity were also performed.ResultsAmong 1929 AYA patients with a mean (SD) age at cancer diagnosis of 28 (8) years, 1049 (54.5%) were female; 5 (0.3%) were American Indian or Alaska Native, 227 (11.8%) were Asian, 157 (8.1%) were Black or African American, 14 (0.7%) were Native Hawaiian or Other Pacific Islander, 1184 (61.4%) were White, 11 (0.6%) were of more than 1 race, 38 (2.0%) were categorized as other race, 293 (15.2%) were without documented race, 514 (26.6%) were Hispanic or Latino, 762 (39.5%) were not Hispanic or Latino, and 653 (33.9%) had no documented ethnicity. Few AYA patients had palliative goals documented in the initial period (139 [7.2%]), increasing to 331 (17.2%) in the middle period and 1113 (57.7%) in the late period. In total, 393 patients (20.4%) transitioned from documented nonpalliative goals in the initial or middle periods to palliative goals by the late period. Many patients had no documented GOC discussion until close to death (initial, 1364 [70.7%]; middle, 969 [50.2%]; and late, 322 [16.7%]). Among the 1929 patients, non-White patients were disproportionately represented among those not having documented GOC discussions (Black, 30 of 157 [19.1%]; Asian, 45 of 227 [19.8%]; and other or undocumented race, 80 of 361 [22.2%]) compared with White patients (167 of 1184 [14.1%]) (P < .001) as were Hispanic or Latino patients (116 of 514 [22.6%]) compared with non-Hispanic patients (93 of 762 [12.2%]) (P < .001) and individuals with no ethnicity documented (113 of 653 [17.3%]) (P < .001).Conclusions and RelevanceIn this cross-sectional study of AYA patients who died of cancer, palliative goals were rarely documented before the last month of life, highlighting the need for timely and ongoing GOC discussions.