Combining Radiotherapy and Immunotherapy: Adverse Events in Lung Cancer

In a retrospective analysis of 29 patients with metastatic lung cancer treated with thoracic radiotherapy and immune checkpoint inhibitors, 3 patients (10%) experienced severe, possibly treatment-related toxicity. Researchers presented these results at the 2017 Multidisciplinary Thoracic Cancers Symposium.¹

Increasingly, cancer therapy combines radiotherapy with immune checkpoint inhibitors to control thoracic tumors within an acceptable limit of treatment-related toxicity. Some effects of this combination had not, however, been thoroughly examined.

In this study, 29 patients received immunotherapy until disease progression. Patients underwent thoracic radiotherapy within 6 months of immunotherapy. Patients had a median of 3 metastatic sites.

Median progression-free survival was 3.8 months; median overall survival was 9.2 months.

One patient experienced a grade 5, possibly treatment-related adverse effect 2 weeks after completion of radiotherapy and 6 weeks after the completion of immunotherapy.

In 2 cases of possible grade 3 treatment-related adverse effects, both patients finished radiotherapy 2 and 4 months previously, respectively, and immunotherapy was completed around 1 to 2 months before initiation of radiotherapy.

“Our results suggest that a treatment regimen combining thoracic radiation therapy and immune checkpoint inhibitors may carry a modest risk of severe side effects,” said lead author Kamran A. Ahmed, MD, a resident in radiation oncology at the Moffitt Cancer Center in Tampa, Florida.

“These findings should be evaluated further within the context of prospective clinical trials, particularly those that examine the risk of lung toxicity and the potential opportunity to improve outcomes with this emerging form of combination therapy.”

Reference

1. Ahmed KA, Grass GD, Creelan B, et al. Tolerability and safety of thoracic radiation and immune checkpoint inhibitors among patients with lung cancer. Paper presented at: 2017 Multidisciplinary Thoracic Cancers Symposium; March 16-18, 2017; San Francisco, CA.