This nationwide, multicentric, retrospective analysis of 1,126,946 COVID-19 cases (March 2020-June 2022) aims to elucidate the impact of COVID-19 vaccination on mortality in patients with a sole solid malignancy.

Using data from the national digital medical record repository, outcomes were compared among fully vaccinated and nonvaccinated cohorts, factoring in gender, virus type, age, vaccination status, vaccine type, and cancer type. Logistic regression calculated odds ratios (OR) and their significance.

Among 6,050 patients with both cancer and comorbidities, 1,797 had only solid malignancy. Vaccinated individuals in this group had reduced mortality rates, especially those >63 years (OR 0.169 [95% confidence interval [CI] 0.090-0.317]; P < .001). Lower deaths were observed in non-ICU (OR 0.193 [95% CI 0.097-0.382]; P < .001) and ICU cases (OR 0.224 [95% CI 0.077-0.646]; P = .003), with both vaccine types. No statistically significant benefits were observed against delta and omicron variants. Intrathoracic malignancies (OR 0.376 [95% CI 0.146-0.971]; P = .043) and palliative treatment (OR 0.384 [95% CI 0.192-0.766]; P = .006) showed vaccination benefits. Logistic regression revealed a higher fatal risk in nonvaccinated males >63. Propensity score matching supported these outcomes.

Patients with sole solid malignancies face elevated COVID-19 mortality risk, particularly without active cytostatic therapy, with advanced disease on palliative treatment, or intrathoracic malignancies.