The Impact of Baseline Vitamin D Level in Patients Receiving Gefitinib-Directed Therapy for EGFR-Mutant Non–Small-Cell Lung Cancer

Abstract

Background: There is contradicting evidence on vitamin D levels and cancer mortality rates. In this study, we aimed to evaluate the impact of baseline vitamin D level on the outcome in patients with epidermal growth factor receptor (EGFR)-mutant advanced non–small-cell lung cancer (NSCLC) who received either gefitinib or gefitinib with chemotherapy (pemetrexed and carboplatin) as first-line therapy in a prospective randomized study. Methods: This was a post hoc analysis of a phase III randomized trial comparing gefitinib with gefitinib with carboplatin and pemetrexed in patients with advanced NSCLC with activating EGFR mutations in the first-line setting. As a part of regular practice, baseline vitamin D levels were measured using circulating 25(OH) levels in blood. We included 334 patients who had baseline vitamin D levels in the study and evaluated the effect of the vitamin D level on oncologic outcomes. Results: There were 136 (40.7%) patients with a sufficient (>20 ng/mL) baseline vitamin D level, and 198 (59.3%) patients who were deficient in vitamin D (<20 ng/mL). The median progression-free survival (PFS) in patients with normal vitamin D levels was 17 months, whereas that in patients with deficient vitamin D levels was 15 months, with a hazard ratio of 1.45 (95% confidence interval [CI] = 1.03-2.06). The median overall survival (OS) in patients with normal vitamin D levels was 28.6 months, whereas that in patients with deficient vitamin D levels was 28.5 months, with a hazard ratio of 1.17 (95% CI = 0.81-1.68). On multivariate analysis, only 2 factors impacted the PFS, the baseline vitamin D level, and the treatment regimen; other factors like age, sex, disease stage, and performance status did not. Conclusions: Baseline vitamin D levels have a significant impact on PFS, whereas OS is not affected by the baseline vitamin D levels on patients receiving targeted therapy for EGFR-mutant lung cancer. Trial registration: The trial was prospectively registered with the Clinical Trial Registry of India, registration number CTRI/2016/08/007149. The date of the registration was 5 August 2016.