Background: Glutamine (Gln) supplementation during concurrent chemoradiotherapy (C-CRT) effectively reduces the incidence and severity of acute radiation-induced esophagitis (RIE). However, there are concerns that Gln might stimulate tumor growth, and therefore negatively impact the outcomes of anticancer treatment. We retrospectively investigated the effect of co-administration of oral Gln during C-CRT on survival outcomes of patients with stage IIIB non-small cell lung carcinoma (NSCLC). We additionally evaluated role of oral Gln in preventing C-CRT-induced weight change, acute and late toxicities.
Methods: The study included 104 patients: 56 (53.8%) received prophylactic powdered Gln (Gln+) orally at a dose of 10 g/8 h and 48 (46.2%) did not receive Gln (Gln-) and served as controls. The prescribed radiation dose to the planning target volume was 66 Gy in 2-Gy fractions. Primary endpoints of progression-free survival (PFS), local/regional progression-free survival (LRPFS), and overall survival (OS) were correlated with status of Gln supplementation.
Results: Oral Gln was well tolerated except for mild nausea/vomiting in 14 (25.0%) patients. There was no C-CRT-related acute or late grade 4-5 toxicity. Administration of Gln was associated with a decrease in the incidence of grade 3 acute radiation-induced esophagitis (RIE) (7.2% vs. 16.7% for Gln+ vs. Gln-; p=0.02) and late-RIE (0% vs. 6.3%; p=0.06), a reduced need for unplanned treatment breaks (7.1% vs. 20.8%; p=0.04), and reduced incidence of weight loss (44.6% vs. 72.9%; p=0.002). At a median follow-up of 24.2 months (range 9.2-34.4) the median OS, LRPFS, and PFS for Gln+ vs. Gln- cohorts were 21.4 vs. 20.4 (p=0.35), 14.2 vs.11.3 (p=0.16), and 10.2 vs. 9.0 months (p=0.11), respectively.
Conclusion: In our study, supplementation with Gln during C-CRT had no detectable negative impact on tumor control and survival outcomes in patients with Stage IIIB NSCLC. Furthermore, Gln appeared to have a beneficial effect with respect to prevention of weight loss and unplanned treatment delays, and reduced the severity and incidence of acute- and late-RIE.