Immunotherapy has become standardized in treating patients with stage IV non-small cell lung cancer (NSCLC), although little is known about the appropriate timing of immunotherapy following ablative therapy. In a study presented at the 2019 ASCO Annual Meeting, researchers used data from the National Cancer Database (NCDB) to analyze trends in immunotherapy use and its timing related to stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) in stage IV NSCLC patients.
NCDB patients included in the analysis were those diagnosed with stage IV NSCLC between 2004 and 2015, treated with SRS or SBRT at any site, and had a minimum of three months follow up. Predictors of immunotherapy use were identified via multivariable logistic regression, and the optimal timepoint between SBRT and immunotherapy correlating with overall survival was found using receiver operator curve analysis. Overall survival was determined through Kaplan-Meier curves, and multivariable Cox regression was employed to identify the predictive factors of survival. By generating a propensity score and integrating it into Kaplan-Meier and cox regressions, the researchers accounted for indication bias.
Of the 13,862 patients included in the analysis, 371 had received immunotherapy treatment, and three-quarters had received chemotherapy as well. Those with adenocarcinoma presence, chemotherapy treatment, and more recent year of treatment were more likely to receive immunotherapy. Improved median survival with immunotherapy was shown via univariable Kaplan-meier analysis (17 months vs. 13 months, P<0.0001). Younger age, lower comorbidity score, lower grade, private insurance, and female gender were found to be significant predictors for improved overall survival through multivariable propensity-adjusted cox regression.
Regarding immunotherapy treatment after SBRT, patients who received treatment at least 21 days after the start of the radiotherapy were found to survive longer (median survival of 19 months vs. 15 months, P=0.0335).
The researchers concluded that the use of immunotherapy in treating stage IV NSCLC after SBRT has increased over time, particularly in patients with adenocarcinoma and those receiving chemotherapy. They also noted that their findings indicate improved outcomes in patients who received immunotherapy at least three weeks after starting SBRT.
Wegner R, Abel S, Hasan S, et al. Time from stereotactic body radiotherapy to immunotherapy as a predictor for outcome in metastatic non small cell lung cancer. Abstract # 9024. Presented at the 2019 ASCO Annual Meeting, Chicago, IL, May 31-June 4, 2019.