Background: Financial distress has been established as a clinically relevant patient-reported outcome (PRO) associated with worse mortality and quality of life, but remains under-recognized by health care providers. Our goal was to define factors associated with financial toxicity (FT) in a public healthcare system. Methods:Patients with advanced lung cancer were recruited from outpatient clinics at the Princess Margaret Cancer Centre (Toronto, Canada). FT was measured with the validated Comprehensive Score for Financial Toxicity (COST) instrument, a 12-item survey scored from 0-44 with lower scores reflecting worse financial well-being. Data on patient and treatment characteristics, total out-of-pocket costs (OOP) and extended insurance coverage (EIC) were collected. Multivariable logistic regression models were fit for COST score and each variable, to determine factors associated with greater FT (COST < 21). Results:Of 251 patients approached, 200 (80%) participated. Median age of the cohort was 65 years; 56% were female, 64% immigrants and 77% employed or on pension. Median total OOP while on treatment ranged between $1000-5000 CAD. Median COST score was 21 (range 0-44). FT was associated with age, with patients < 65 years reporting greater FT than older patients (COST 18.0 vs. 24.0, p < 0.0001). In multivariable logistic regression analysis, younger age was associated with greater FT, when adjusting for income, employment status, OOP and EIC (OR 3.6, [95% CI, 1.5-9.1]; p < 0.0001). Total OOP > $1000 and EIC also were associated with greater FT (adjusted OR 5.0 [95% CI, 2.0-12.1] and 3.7 [95% CI, 1.5-9.1], respectively). Conclusions:Age is significantly associated with FT in the Canadian (Ontario) public healthcare system, with younger lung cancer patients reporting greater financial distress. This study highlights priority patient populations where FT should be routinely assessed and appropriate resources for support offered.