Abstract
To evaluate the impact of comorbidities on treatment allocation and prognosis in anaplastic thyroid cancer, 137 patients from 10 German tertiary cancer centers treated with radiotherapy between 2001 and 2020 were analyzed. Four validated comorbidity scores were applied to assess comorbidity burden. The primary objective was to identify prognostic factors for the survival rate at 6 months after radiotherapy and discriminate the comorbidity scores using concordance statistics, ROC curve net reclassification index, and integrated discrimination improvement for 6-month survival. The median overall survival (OS) of the entire cohort was 4 months (95% CI = 2.72-5.28). The 6-, 12- and 24-months survival rates were 42.1%, 29.0% and 15.0%, respectively. In the univariate analysis, Karnofsky Performance Score (KPS) (> 70%, p < 0.001), UICC stage (p < 0.001), treatment modality (p < 0.001), intention of treatment (p < 0.001) as well as lower scores in the conventional Charlson Comorbidity Index (cCCI, p < 0.001), the updated Charlson Comorbidity Index (uCCI, p < 0.001) were associated with improved OS. KPS (> 70%, p = 0.06) and type of therapy (p = 0.087) showed a trend in multivariate analysis. Higher comorbidity burden (cCCI and uCCI) was associated with less intensive treatment and lower cumulative radiation doses in univariable analyses. However, after adjustment for age and metastatic status, none of the comorbidity indices remained independently associated with the use of multimodal therapy or the prescribed EQD2 dose (p > 0.05). Age, but not metastatic status, was linked to a reduced likelihood of receiving multimodal treatment. In contrast, KPS emerged as the only independent predictor of higher EQD2 dose levels in the multivariable models.