ObjectiveTo investigate the clinical characteristics of patients with small cell lung cancer (SCLC) complicated with hyponatremia and its relationship with chemotherapy efficacy, so as to provide theoretical basis for improving the prognosis of patients with SCLC complicated with hyponatremia.

MethodsOne hundred and six SCLC patients were selected, including 38 patients with hyponatremia and 68 patients with normal serum sodium level.All patients were treated with etoposide combined with platinum regimen for 2 consecutive cycles.The general clinical data of hyponatremia group and normal blood sodium group were analyzed, the short-term efficacy was evaluated according to the RECIST 1.1, and the adverse reactions were analyzed according to NCICTCAE 3.0.Th e hyponatremia group was subdivided into blood sodium corrected group and blood sodium uncorrected group according to whether the blood sodium was corrected or not after chemotherapy, and the relationship with clinical efficacy was analyzed.The patients were divided into disease control group and disease progression group according to the chemotherapy efficacy.The levels of gastrin-releasing peptide precursor (ProGRP) and neuron-specific enolase (NSE) before and after chemotherapy were compared between the two groups, and the correlation between the serum sodium level and ProGRP, NSE levels was analyzed.

ResultsThe incidence of SCLC complicated with hyponatremia was 15.83% (38/240).There were significant differences in clinical stage, bone metastasis, pleural effusion, NSE level and ProGRP level between SCLC with hyponatremia group and normal sodium group (P < 0.05).The objective remission rate (ORR) and disease control rate (DCR) in the hyponatremia group were lower than those in the normal sodium group (P < 0.05).Compared with the normal blood sodium group, the patients in the hyponatremia group were more likely to have gastrointestinal reactions, and the difference of which was statistically significant (P < 0 05).The ORR and DCR of patients in the sodium corrected group were higher than those in blood sodium uncorrected group (P < 0.05).Before chemotherapy, there was no significant difference in NSE level between the disease progression group and the disease control group (P>0.05), and the level of ProGRP in the disease progression group was higher than that in the disease control group (P < 0.05).The difference of ProGRP and NSE levels in the disease progression group between before and after chemotherapy was not statistically significant (P>0.05), and the levels of ProGRP and NSE in the disease control group after chemotherapy were lower than those before chemotherapy (P < 0.05).After chemotherapy, there was no significant difference in NSE level between the two groups (P>0.05), and the level of ProGRP in the disease progression group was significantly higher than that in the disease control group (P < 0.01).The serum sodium level in SCLC patients was negatively correlated with NSE and ProGRP levels (r=-0.588, -0.642, P < 0.05).

ConclusionsPatients with SCLC complicated with hyponatremia have a later clinical stage, are more likely to have bone metastasis and pleural effusion, have poor response to chemotherapy and similar adverse reactions, but the patients with hyponatremia are more likely to have gastrointestinal adverse reactions.The prognosis of patients with corrected blood sodium after treatment is better than that of patients with uncorrected hyponatremia.Serum sodium level is negatively correlated with ProGRP and NSE levels.Therefore, SCLC with hyponatremia is an indicator of poor prognosis, and correction of hyponatremia may improve the prognosis of patients.