Association of urinary sodium and potassium excretion with outcomes of neuroendocrine cancer.

Background: Sodium and potassium imbalances are pervasive in patients with neuroendocrine cancer (NEC), partly due to syndrome of inappropriate antidiuretic hormone secretion, which impact their prognosis. Whether urinary sodium and potassium excretion is associated with outcomes in patients with NEC remains unknown. Methods: We conducted a retrospective analysis of 759 patients diagnosed with NEC enrolled in a UK biobank cohort range from 2000 to 2020. Cox proportional hazards models was used to examine the associations between urinary sodium and potassium excretion. Interaction and stratified analyses were conducted including gender, age, NEC primary site, hypertension and sodium intake. Results: Among the 759 NEC patients, 54.81% were male and 45.19% were female, with a mean age of 52.69 ± 6.11 years. During a median follow-up period of 14.0 months, there were 586 overall deaths and 549 cancer-specific deaths. After adjusting for confounding factors, the urinary sodium-to-potassium ratio (STP) was significantly associated with both overall mortality (HR = 1.16, 95% CI: 1.05-1.28) and cancer-specific mortality (HR = 1.16, 95% CI: 1.05-1.28). When comparing the higher STP group (≥1.29) with the lower STP group (<1.29), the HR was 1.26 (95% CI: 1.04-1.52) for overall mortality and 1.26 (95% CI: 1.04-1.53) for cancer-specific mortality after full adjustment. Additional sensitivity analyses restricted to pulmonary NEC and stratified by primary tumor site showed directionally consistent results. Conclusion: Higher urinary sodium and lower potassium excretion, as measured by the STP ratio, were associated with increased risks of both overall mortality and cancer-specific mortality in patients with NEC. Our findings suggest that the STP ratio, a parsimonious clinic-ready marker, could provide incremental prognostic information for NEC patients.