CHICAGO – Thoracic radiation used in combination with chemotherapy may improve survival outcomes compared with chemotherapy alone in patients with extensive-stage small cell lung cancer, according to findings presented at the ASCO Annual Meeting.
“There is conflicting prospective data about whether the receipt of thoracic radiation confers a survival benefit in patients who also received chemotherapy compared with patients who received chemotherapy alone,” Kristin Higgins, MD, assistant professor in the department of radiation oncology at Emory University School of Medicine and medical director of radiation oncology at The Emory Clinic at Winship Cancer Institute's Clifton campus, said in an interview. “We performed a retrospective analysis of patients with extensive-stage small cell lung cancer to analyze the effects of consolidative radiation after chemotherapy.”
Higgins and colleagues used the National Cancer Database to analyze OS in patients treated with chemotherapy alone compared with patients who received chemotherapy and thoracic radiation between 2010 and 2013. Patients with brain metastases at the time of diagnosis and patients who were treated with radiation prior to the start of chemotherapy were omitted.
The median age of patients in the study was 66 years. The median age of patients who received chemotherapy was also 66 years, but the median age of patients treated with chemotherapy and radiation was 63 years (P < 0.001).
“There were some differences in the baseline characteristics of the patient population; the main one is that patients who received thoracic radiation were slightly younger and had a better performance status,” Higgins told HemOnc Today. “These are the caveats of a retrospective analysis.”
The study included 14,367 patients. Most were treated with chemotherapy alone (n = 12,019); the rest received chemotherapy and thoracic radiation (n = 2,348). Slightly more than half of the patients were men (51%); 52% of patients in the chemotherapy arm were men compared with 49% in the chemotherapy plus thoracic radiation arm (P < .001). A Charlson/Deyo combined comorbidity score of zero was reported in 53% of the total patient population; a score of zero was more common among patients in the chemotherapy plus thoracic radiation arm (57%) compared with the chemotherapy arm (52%; P < .001).
The median total dose of thoracic radiation was 45 Gy in the chemotherapy plus thoracic radiation group. A multivariate analysis demonstrated that chemotherapy alone correlated with a higher risk for death compared with chemotherapy and thoracic radiation [HR = 1.74 (range, 1.65-1.84); P < .001]. The 5-year OS was 7% for patients receiving chemotherapy plus thoracic radiation and 2% for patients receiving chemotherapy alone (P < .001). Chemotherapy plus thoracic radiation enhanced 5-year OS compared with chemotherapy alone on propensity matched analysis (8% vs. 2%; P < .001). Multivariate analysis of propensity-matched samples demonstrated that chemotherapy alone was consistently associated with decreased survival [HR = 1.76 (range, 1.62-1.91); P < .001).
“At five years, the receipt of thoracic radiation conferred a survival benefit,” Higgins said. “With the conflicting prospective data, this is important information to have.”
The results could help to streamline the next steps for patients with extensive-stage small cell lung cancer who have received chemotherapy, she continued.
“When these patients relapse after chemotherapy, there aren’t many effective systemic therapies,” Higgins said. “This study demonstrates that we can potentially increase survival with thoracic radiation.” – by Julia Ernst, MS
Higgins KA, et al. Abstract 8565. Presented at: ASCO Annual Meeting; June 2-6, 2017; Chicago.
Disclosures: Higgins reports that she serves as a consultant for AstraZeneca. Please see the full study for a list of all other researchers’ relevant financial disclosures.