Impact of thoracic radiation therapy after chemotherapy on survival in extensive-stage small cell lung cancer: A propensity score-matched analysis

The benefit of radiotherapy in distant metastatic small-cell lung cancer: A retrospective study based on propensity score matching (PSM)

Due to extensive tumor spread, systemic chemotherapy is the main treatment for distant metastatic small-cell lung cancer (DM-SCLC). It is still unclear whether adding local radiotherapy (RT) on the basis of chemotherapy can improve the long-term survival of patients with DM-SCLC. This study aims to explore the population with DM-SCLC who can benefit from RT. Patients with metastatic SCLC with complete data were collected from the Surveillance, Epidemiology, and End Results database and divided into 2 groups according to whether RT was given or not. The propensity score matching method was used to balance the covariate differences between the RT group and the non-RT group. Lasso Cox regression model and Cox proportional hazards regression analyses were used to identifying independent risk factors affecting survival. Kaplan-Meier method was used to calculate the survival rate. P < .05 was considered statistically significant. After matching, there were 3150 patients in both groups. Sex, tumor size, N stage, RT, chemotherapy, brain metastasis, liver metastasis, age, and site metastasis were independent factors of survival in DM-SCLC. The 1- and 2-year survival rates were 24.5% and 5.8% in the RT group and 14.8% and 2.3% in the non-RT group (P < .001). The median survival time of the RT group was 9 months, and that of the non-RT group was 7 months, and the difference was statistically significant (P < .001). RT improved survival in all sex subgroups, any N stage subgroup, any tumor size subgroup, no brain metastases subgroup, no liver metastases subgroup, any age subgroup, and 1-2 organ metastases subgroup. RT improves 1- and 2-year survival in DM-SCLC.

Radiation therapy for extensive-stage small-cell lung cancer in the era of immunotherapy

Unlike non-small-cell lung cancer (NSCLC), the progression of small-cell lung cancer (SCLC) is slow. Extensive-stage SCLC (ES-SCLC) is a serious threat to human health, with a 5-year survival rate of <7%. Chemotherapy has been the first-line treatment for the past 30 years. The anti-PD-L1 checkpoint blockades durvalumab and atezolizumab have greatly prolonged overall survival and have become the standard first-line therapy for ES-SCLC since the CASPIAN and IMpower133 trials. In the era of chemotherapy, radiation therapy (RT), including thoracic radiation therapy (TRT) and brain radiation therapy (BRT), has shown clinical effects in randomized and retrospective studies on ES-SCLC. RT-immunotherapy has shown exciting synergistic effects in NSCLC. For ES-SCLC, the clinical effects of combining TRT/BRT with immunotherapy have not yet been systematically explored. In this review, we found that studies on RT-immunotherapy in ES-SCLC are relatively few and limited to early phase studies focusing on toxicity. The efficacy and safety profiles of early phase studies encourage prospective clinical trials. In this review, we discuss the best population, optimum TRT dose, proper TRT time, and strategies for reducing radiation-induced neurotoxicity. Furthermore, we suggest that biomarkers and patient performance status should be fully assessed before RT-immunotherapy treatment. Prospective trials are needed to provide more evidence for RT-immunotherapy applications in ES-SCLC.

Role of thoracic radiotherapy in extensive stage small cell lung cancer: a systemic review and meta-analysis

Background

The role of thoracic consolidation radiotherapy in patients with extensive stage small cell lung cancer (ES-SCLC) remains controversial. This study aimed to evaluate the efficacy of thoracic radiotherapy (TRT) in these patients.

Methods

A systematic literature search was performed in PubMed, Embase, and the Cochrane library to identify qualified clinical studies. The hazard ratios (HRs) and 95% confidence intervals (CIs) of overall survival (OS), progression-free survival (PFS) and local recurrence-free survival (LRFS) were extracted, and toxicity of the TRT group versus non-TRT group was analyzed.

Results

A total of 12 studies were included in this meta-analysis, including 936 patients in the TRT group and 1,059 patients in the non-TRT group. The combined results showed that TRT significantly improved OS (HR =0.65; 95% CI: 0.55–0.77, P<0.00001), PFS (HR =0.64; 95% CI: 0.56–0.72, P<0.00001) and LRFS (HR =0.38, 95% CI: 0.26–0.53, P<0.00001). Subgroup analysis showed that OS benefits were observed in patients receiving sequential TRT (HR =0.67; 95% CI: 0.54–0.84, P=0.0006). The addition of TRT significantly improved OS in patients over 65 years of age (HR =0.55; 95% CI: 0.40–0.74, P=0.0001). For patients with only one organ metastasis, there was no significant difference in OS between the two groups (HR =0.61; 95% CI: 0.36–1.01, P=0.06). There was no statistical difference in hematologic toxicity (leukopenia, thrombocytopenia, anemia) and non-hematologic toxicity (nausea or vomiting) between the two groups. The incidence of grade ≥3 esophageal toxicity was 4.6% in the TRT group and 0% in the non-TRT group (P=0.0001). Grade ≥3 bronchopulmonary toxicity was 2.9% in the TRT group and 0.8% in the non-TRT group (P=0.02).

Conclusions

TRT improves OS, PFS and LRFS in patients with ES-SCLC, with a low increase in esophageal and bronchopulmonary toxicity. More randomized controlled trials (RCTs) are expected to confirm our conclusions.

PROSPERO registration number

CRD42020190575.