AbstractBackgroundKidney function is associated with clinical outcomes in patients with cancer.ObjectivesThis study aimed to assess the association between kidney function decline and cancer‐related mortality among community‐dwelling elderly individuals.DesignThis was a retrospective longitudinal cohort study.ParticipantsThe 61,988 participants were from an elderly health examination database in Taipei City from 2005 to 2012.MeasurementsMultivariable logistic regression was used to assess the association between baseline covariates and rapidly deteriorating estimated glomerular filtration rate (eGFR). In addition, Cox proportional hazards model and the Fine–Gray model were used to quantify the effects of covariates on total cancer mortality and six specific cancer mortalities.ResultsDuring the follow‐up period, 1482 participants died of cancer. Their baseline average eGFR was 73.8 ± 19.9 mL/min/1.73 m2, and 18.3% had rapid renal function decline (≥5 mL/min/1.73 m2per year). Rapid renal function decline was positively related to age, baseline eGFR, proteinuria, hypertension, waist circumferences, high log triglyceride levels, and diabetes mellitus (DM) history. In Cox proportional hazard models, participants with rapid eGFR decline had an increased risk of cancer mortality [hazard ratio (95% CI): 1.97 (1.73, 2.24);p< 0.001] compared to those without rapid eGFR decline. In the analysis of site‐specific cancer mortality risk, rapid eGFR decline was associated with six site‐specific cancer mortality, namely gastrointestinal tract, hepatobiliary, lung, prostate, urinary tract, and hematological malignancies.ConclusionsElderly individuals with rapid kidney function decline had higher cancer mortality risks. Serial assessments of dynamic changes in eGFR might provide information relevant for cancer prognosis.