Thoracic Radiotherapy Benefits Patients With Extensive-Stage Small Cell Lung Cancer Who Responded to Chemotherapy
In a phase III trial reported in The Lancet, Slotman et al found that while thoracic radiotherapy vs no thoracic radiotherapy was not associated with a significant improvement in 1-year overall survival, the primary endpoint of the study, it significantly improved 2-year overall survival and reduced risk of progression in patients with extensive-stage small cell lung cancer who had responded to prior chemotherapy.
Study Details
In this unblinded trial, 495 patients with extensive-stage small cell lung cancer from 42 hospitals in the Netherlands, United Kingdom, Norway, and Belgium who responded to four to six cycles of standard chemotherapy (platinum and etoposide) were randomly assigned between February 2009 and December 2012 to receive thoracic radiotherapy at 30 Gy in 10 fractions (n =247) or no thoracic radiotherapy (n = 248). All patients had prophylactic cranial irradiation.
The radiotherapy and control groups were generally balanced for age (median 63 years in both, 6% and 9% ≥ 75 years), sex (55% male in both), World Health Organization performance status (0 in 39% and 28%, 1 in 49% and 63%), response to chemotherapy (complete in 5% in both, partial in 73% and 69%, good in 22% and 26%), and persistent intrathoracic disease (87% and 88%). The mean duration between diagnosis and randomization was 17 weeks.
Efficacy Outcomes
Median follow-up was 24 months. Overall survival at 1 year was 33% (95% confidence interval [CI] = 27%–39%) in the radiotherapy group vs 28% (95% CI = 22%–34%) in the control group (hazard ratio [HR] = 0.84, P = .066), with no differences observed between treatments in subgroup analyses. Median overall survival was 8 months in both groups. Two-year overall survival was 13% (95% CI = 9%–19%) vs 3% (95% CI = 2%–8%; P = .004). Progression was less likely in the thoracic radiotherapy group vs the control group (HR = 0.73, P = .001). Median progression-free survival was 4 months vs 3 months; 6-month progression-free survival was 24% vs 7% (P = .001).
Adverse Events
Adverse events of ≥ grade 3 occurred in 10.5% of the radiotherapy group, with the most common being fatigue (4.5%), esophagitis (1.6%), dyspnea (1.2%), insomnia (1.2%), and headache (1.2%) vs 7.3% of the control group (P = .28), with the most common being fatigue (3.6%) and dyspnea (1.6%).
The investigators concluded: “Thoracic radiotherapy in addition to prophylactic cranial irradiation should be considered for all patients with [extensive-stage small cell lung cancer] who respond to chemotherapy.”
Ben J. Slotman, MD, of VU University Medical Center, Amsterdam, is the corresponding author for The Lancet article.
The study was funding by the Dutch Cancer Society, Dutch Lung Cancer Research Group, Cancer Research UK, Manchester Academic Health Science Centre Trials Coordination Unit, and UK National Cancer Research Network.
The study authors reported no potential conflicts of interest.
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