Palliative radiotherapy in advanced cancer patients treated with immune-checkpoint inhibitors: The PRACTICE study

In the present study, the influence of purely palliative radiotherapy (pRT) on the outcomes of patients with advanced cancer undergoing immune checkpoint blockade was evaluated. Patients were stratified into three groups: Patients who had received pRT within 6 months prior to the initiation of immunotherapy (previous pRT); patients who received pRT during immunotherapy (concurrent pRT); and patients who did not receive RT prior to or during immunotherapy (no RT group), and these groups were compared. The median overall survival (mOS), median progression free survival (mPFS) and median time-to-treatment failure (mTTF) for the previous pRT group were significantly shorter compared with the no RT group (mOS, 3.6 vs. 12.1 months, respectively, P=0.0095; mPFS 1.8 vs. 5.4 months, respectively, P=0.0016; mTTF 1.8 vs. 5.7 months, respectively, P=0.0035). The concurrent pRT group had a longer mTTF compared with the previous pRT group and similar outcomes to the no RT group. In the previous pRT group, 26.9% of the patients experienced immune-related adverse events compared with 40.1% of patients in the no RT group. Despite the use of pRT during immunotherapy being considered safe, the results of the present study suggest that pRT has a negative effect on immune balance.