BACKGROUND AND AIM: Small‑cell lung cancer (SCLC) is fast‑growing disease with high mortality and prognosis is worse when hyponatremia develops. In our study, we aimed to determine the frequency of hyponatremia in SCLC and the relationship with the prognosis.

MATERIALS AND METHODS: Patients diagnosed with SCLC between 2012 and 2017 were retrospectively screened. Stages, hyponatremia levels, and survival times were recorded.

RESULTS: A total of 466 patients diagnosed with SCLC, 423 (90.8%) of whom were male were included in the study. The average age was 67 ± 10 years. About 126 (27%) of the patients were hyponatremic and 340 (73%) were normonatremic. Hypertonic saline treatment was performed in 52 (41.3%) patients. In total, hyponatremia improved in 49.2% (n = 62). While the expected survival means were 12.6 months in those with improved hyponatremia, 5.0 months in those with not improved, and 12.3 months in the normonatremic group. Survival in the group of whom hyponatremia could not be corrected was found to be statistically different (P < 0.05).

CONCLUSION: The improvement of hyponatremia was found to be a positive independent factor on the survival of SCLC.