Impact of comorbidity on survival after palliative radiotherapy.

Abstract

To evaluate prognostic factors for survival after palliative radiotherapy (PRT) with consideration of different comorbidities and the Charlson comorbidity index (CCI). Between 2007 and 2012, 525 consecutive patients were treated with PRT and included in this retrospective study. Most patients received PRT for bone metastases, for brain metastases, or in order to improve thoracic symptoms from lung cancer. Median age was 69 years. Uni- and multivariate analyses were performed. Only 7% of patients had no comorbidity. A CCI of 1–2 was present in 49%, a CCI of 3–4, in 36%, and a higher CCI in 9% of patients. Younger patients, female patients, and patients who had not been smokers had significantly less comorbidity. Patients without comorbidity had significantly better median performance status (PS) and were more likely to receive palliative systemic therapy. Both lower CCI and absence of more than one cancer diagnosis independently predicted longer survival. Further significant parameters in multivariate analysis were PS and number of organs with metastatic involvement. Exploratory analyses suggested that the impact of CCI was largest in patients older than 60 years and was absent in those with brain metastases. We recommend assessment of comorbidity when prescribing PRT and selecting the optimal fractionation regimen, because most patients with severe comorbidities had limited survival. One of the possible explanations could be that only a minority of these patients are fit for systemic therapy, which plays an important role in the overall treatment concept.