Background: Within melanoma, comorbidity is associated with delayed diagnosis, advanced stage, and less aggressive treatment. Using the National Cancer Database (NCDB), this is the largest study to determine the influence of comorbidity (Charlson-Deyo) on receipt of adjuvant immunotherapy and survival in stage III melanoma.
Methods: We identified 10,739 patients with stage III melanoma between 2006-2012, for which high dose interferon was the standard adjuvant treatment. The probability of receipt was estimated using multivariable marginal logistic regression model, whereas survival was estimated using both the Kaplan-Meier method and multivariable marginal Cox regression model. Multivariable models adjusted for patient and facility-level characteristics.
Results: Greater receipt of adjuvant immunotherapy was observed in patients with fewer comorbidities (28.2%, 23.6%, and 13.8%, respectively, for 0, 1, and 2 or more comorbidities; P < .001). Patients with two or more comorbid conditions had a 44.0% lower adjusted odds of receiving adjuvant immunotherapy relative to patients with none (P < .001), and 45.5% lower adjusted odds relative to 1 comorbidity (P < .001). Regarding survival estimates, patients receiving adjuvant immunotherapy had significantly longer survival with fewer than 2 comorbid conditions (both P < .001); no difference was observed in patients with 2 or more (P = .077). In patients with no comorbidities, at 5-years postdiagnosis, 60.4% of those receiving adjuvant immunotherapy were alive compared to 49.8% of those who did not. In patients with 1 comorbid condition, 51.3% of those receiving adjuvant immunotherapy were alive compared to 37.7% of those who did not. The adjusted risk of death in patients who received adjuvant immunotherapy was not moderated by the number of comorbidities (χ2 = 0.51, P = .775). As such, the 20.4% lower risk of death favoring patients who received adjuvant immunotherapy (P < .001) was constant across different numbers of comorbidities. Lower risk of death and receipt of adjuvant immunotherapy were observed in younger patients with private insurance.
Conclusions: Risk of death findings suggest that adjuvant immunotherapy works equally well across numbers of comorbidities, despite a decrease in receipt with greater comorbidity. Additionally, overall survival findings support this in patients with 1 comorbidity.
