A recent publication suggest that thymectomy is associated with increased mortality and cancer risk following the procedure. We aim in this study to validate and extend these findings.

We identified thymectomy patients and patients who underwent coronary artery bypass grafting (CABG) or valve replacement surgery between the years 1986-2025. All patients who died within 90 days of surgery were excluded. Controls with prior myocardial infarction or prior thymectomy were excluded. Kaplan–Meier analysis and propensity score matching by age and sex were used.

Among 425 thymectomy patients (median age 54 years; 50.4% women) and 5,401 matched controls (median age 67 years; 32.6% women), survival did not differ significantly after adjustment for baseline characteristics (hazard ratio 0.78; 95% CI 0.54–1.13; p = 0.19).Among thymectomy patients, survival varied according to indication. Those with thymic malignancy had markedly worse outcomes than patients without malignancy (p<0.0001), whereas myasthenia gravis (MG) was not associated with reduced survival (p=0.14). Survival did not differ by sex within the thymectomy group (p=0.64), although in the control cohort, female sex was associated with higher mortality (p<0.0001). In both cohorts, advancing age correlated with increased mortality (p<0.0001). After matching for age and sex, survival curves between the thymectomy and control groups showed no significant difference (p=0.077).

Thymectomy was not associated with increased mortality compared with matched controls. Thymic malignancy, but not myasthenia gravis, was linked to poorer survival. Older age remained the principal predictor of mortality, while sex influenced outcomes only in the control cohort. These findings suggest that previously reported adverse survival after thymectomy may reflect baseline confounding rather than a causal effect.