Impacts of perioperative hyponatremia relevant to outcomes and prognosis of non-small cell lung cancer in octogenarians.

BACKGROUND: A recent study reported the effect of preoperative hyponatremia on postoperative outcomes of patients with non-small cell lung cancer. However, the influence of postoperative hyponatremia on postoperative outcomes has not been completely investigated. METHODS: We retrospectively studied 75 octogenarians who underwent pulmonary surgery for non-small cell lung cancer between 2009 and 2018. We divided them into hyponatremic and non-hyponatremic groups, depending on preoperative and immediate postoperative serum sodium levels, and investigated their clinicopathological characteristics and outcomes. Disease-specific survival and cumulative incidence of relapse rates between the two groups were calculated and compared using the stratified Kaplan-Meier method. Univariable and multivariable analyses were performed to identify prognostic factors. RESULTS: Preoperative hyponatremia was associated with 66.7% of postoperative respiratory and 88.9% of non-cardiovascular complications. The long-term prognosis of the postoperative hyponatremic group was significantly worse than that of their counterpart. The 3-year disease-specific survival and 3-year cumulative incidence of relapse rate were 55.9% and 46.2%, respectively, and the median observation period after surgery was 37.4 (interquartile range, 23.7-51.0) months for the entire cohort. Kaplan-Meier curves showed that hyponatremia was associated with worse disease-specific survival and cumulative incidence of relapse. Multivariable analysis identified hyponatremia as a factor that predicted unfavorable disease-specific survival and cumulative incidence of relapse. CONCLUSIONS: Immediate postoperative hyponatremia is an independent predictor of non-small cell lung cancer outcomes among octogenarians. Preoperative hyponatremia was associated with a high frequency of postoperative respiratory and non-cardiovascular complications. Surgical indications in older patients with hyponatremia should be carefully considered with follow-up.