Objective Assess validity of the retrospective Dartmouth hospital referral region (HRR) end‐of‐life spending measures by comparing with health care expenditures from diagnosis to death for prospectively identified advanced lung cancer patients. Data/Setting/Design We calculated health care spending from diagnosis (2003–2005) to death or through 2011 for 885 patients aged ≥65 years with advanced lung cancer using Medicare claims. We assessed the association between Dartmouth HRR‐level spending in the last 2 years of life and patient‐level spending using linear regression with random HRR effects, adjusting for patient characteristics. Findings For each $1 increase in the Dartmouth metric, spending for our cohort increased by $0.74 (p < .001). The Dartmouth spending variable explained 93.4 percent of the HRR‐level variance in observed spending. Conclusions HRR‐level spending estimates for deceased patient cohorts reflect area‐level care intensity for prospectively identified advanced lung cancer patients.