Should Radiotherapy Be Added to Immunotherapy in Small Cell Lung Cancer?

ContributorsProf. Dr. Mustafa ÖzdoğanAuthor · Medical review · Editorial approval

PublishedJan 6, 2026

UpdatedOct 17, 2026

3 min read

Should Radiotherapy Be Added to Immunotherapy in Small Cell Lung Cancer?

In this article

Adding Radiotherapy to Immunotherapy Shifts the Balance in Small Cell Lung Cancer

Why Does It Matter?

Extensive-stage small cell lung cancer (ES-SCLC) is known for rapid spread. Until recently, standard treatment was chemotherapy alone. Adding immunotherapy, atezolizumab or durvalumab, has created a new standard and extended survival.

Yet oncologists still had a major question: "Thoracic radiotherapy (cTRT) helped when we gave chemotherapy alone. Should it still be added with immunotherapy, or would increased side effects, particularly lung inflammation, harm patients?"

On 5 January 2026, Radiotherapy and Oncology published a large analysis involving over 5000 patients that answers yes. It demonstrates that adding radiotherapy in appropriately selected patients extends survival by 40 percent .

Clinical Glossary: Understanding the Terms

ES-SCLC (Extensive-Stage Small Cell Lung Cancer): Disease extending beyond the lung into the opposite lung or distant organs.

cTRT (Consolidative Thoracic Radiotherapy): Consolidation radiation to the chest after chemotherapy and immunotherapy, intended to eliminate or control residual lung tumor.

Chemo-Immunotherapy: Standard chemotherapy, usually platinum+etoposide, combined with drugs that enhance immune activity.

Pneumonitis: Inflammation of lung tissue. Both immunotherapy and radiotherapy can cause it, and combining them may increase risk.

A Large Meta-Analysis: Data from 5000 Patients

Dr. Dominik Wróbel and colleagues at Poland's Jagiellonian University combined 20 studies with 5282 patients worldwide. Patients fell into two main groups:

Group 1: Triple Treatment (2436 Patients)

Chemo-immunotherapy plus thoracic radiotherapy (cTRT).

Group 2: Standard Treatment (2846 Patients)

Chemo-immunotherapy without radiotherapy.

Results: Radiotherapy Makes a Difference

The analysis found a statistically significant and clinically substantial survival advantage from adding radiotherapy.

Average Survival (Median OS)

Radiotherapy Group 20.25 Months

Drug-Treatment-Only Group 14.55 Months

Radiotherapy provided an average of 6 additional months of life (HR: 0.57, P < .001).

Progression-Free Survival (PFS)

Without Radiotherapy: 6.47 Months

With Radiotherapy: 9.85 Months

Who Should Receive Radiotherapy?

The most critical findings identify which metastatic sites are associated with radiotherapy benefit.

Brain Metastases: CLEAR BENEFIT In patients with brain metastases at baseline, thoracic radiotherapy improved overall survival (HR: 0.57) and intracranial disease control. Researchers suggest an abscopal effect, in which radiation stimulates immunity at a distance to affect the brain.

Liver Metastases: NO BENEFIT Adding radiotherapy did not extend survival in patients with liver metastases. Avoiding its additional burden may be more appropriate for this group.

The Other Side: Adverse Effects

Both immunotherapy and radiotherapy can inflame the lungs. Does combining them increase risk? Yes.

Pneumonitis (Lung Inflammation): Risk rose substantially with radiotherapy. Severe pneumonitis (Grade 3 or higher) occurred in 3.86%.
Esophagitis (Esophageal Inflammation): Severe esophageal inflammation occurred in 1.27% of radiotherapy-treated patients.

DROZDOGAN Academy Commentary

Small cell lung cancer is entering the personalized medicine era. Treatment should be tailored to metastatic sites rather than applied identically to everyone.

The study strongly supports cTRT after a good initial chemo-immunotherapy response in patients with brain metastases as part of standard treatment. A median survival of 20 months is a major gain in this disease.

For patients with liver metastases or limited lung capacity and high pneumonitis risk, avoiding radiotherapy appears more consistent with first doing no harm. Ongoing RAPTOR and TREASURE trials will clarify the strategy.

Source:

Wróbel D, Wojewoda B, Ziółek W, et al. Consolidative thoracic radiotherapy in the immunotherapy era for extensive-stage small cell lung cancer: a systematic review and meta-analysis with emphasis on brain and liver metastases. Radiotherapy and Oncology. Published online December 10, 2025. doi:10.1016/j.radonc.2025.111328

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Should Radiotherapy Be Added to Immunotherapy in Small Cell Lung Cancer?