Prognostic Importance Of Pretreatment Sodium Levels In Patients Of Nsclc Treated With Pemetrexed- Platinum Doublet Chemotherapy

e18510 Background: A recent study has shown pretreatment sodium level to be a predictive and prognostic marker in NSCLC patients treated with erlotinib. Low serum sodium (LSS) has been associated with poor outcome in other conditions such as hepatocellular carcinoma, gastric cancer and small cell lung cancer. The objective of this study was to evaluate the prognostic impact of pretreatment sodium levels on progression free survival (PFS) and overall survival (OS) in patients of NSCLC treated with pemetrexed-platinum doublet chemotherapy. Methods: Stage IIIB/IV NSCLC patients aged ≥ 18 years treated between January 2011 to November 2014 at our centre were included in this retrospective study. Patients received pemetrexed 500 mg/m2 with either cisplatin 75 mg/m2or carboplatin (AUC 5) on day 1 of a 21 day cycle for 6 cycles followed by maintenance pemetrexed till progression. Electronic medical record (EMR) database of our hospital was used to retrieve demographic data, pretreatment sodium levels, PFS and OS data. LSS was defined as serum sodium < 136mEq/L. Survival analysis was performed using Kaplan-meier curves and compared between LSS and normal serum sodium (NSS) groups using Log-Rank test. Results: Data was available for 256 patients (M/F = 172/84) with median age of 53 (25-79) yrs. Majority had EGOG PS of 1 (0 = 34, 1 = 172, 2 = 44, 3 = 6). Stage IIIb = 24 (9%), stage IV = 232 (91%). Pretreatment LSS was observed in 75(29%) patients while 181(71%) had NSS. Baseline characteristics were comparable between LSS and NSS groups. Median duration of follow-up was 17 months. Patients with NSS had significantly longer PFS (10.7 vs. 7.4 months; P < 0.05) and OS (17.6 vs. 13.4 months; P < 0.05) compared to LSS group. Conclusions: Pretreatment serum sodium levels is an important prognostic marker in stage IIIB/IV NSCLC patients. The simple possibility of testing coupled with low cost makes it an attractive marker to implement in clinical practice.