Association between proteinuria changes and colorectal cancer incidence: evidence from a nationwide cohort study.

Background: The presence of excess proteins in the urine, known as proteinuria, has been linked to various health conditions, including chronic kidney disease and cancer. Emerging evidence suggests an association between proteinuria and colorectal cancer, a leading global cause of cancer-related morbidity and mortality. However, the impact of changes in proteinuria status on colorectal cancer risk remains unclear. Understanding this relationship may identify proteinuria as a modifiable risk factor for colorectal cancer prevention.

Methods: This retrospective cohort study analyzed data from 3,043,138 adults aged over 19 years who participated in biennial health screenings by the South Korean National Health Insurance Service in 2010 and 2012. Participants were classified into four groups based on changes in proteinuria status: no proteinuria, newly developed proteinuria, recovered proteinuria, and persistent proteinuria. Proteinuria was measured using dipstick urinalysis, and colorectal cancer diagnoses were identified using medical records. Cox proportional hazards models adjusted for age, sex, body mass index, lifestyle behaviors, and other confounders were used to estimate cancer risk.

Results: Over a median follow-up period of 9.19 years, 36,846 participants (1.2%) developed colorectal cancer. After adjusting for multiple confounding factors, including age, sex, lifestyle behaviors, medication use, diabetes, hypertension, dyslipidemia, and chronic kidney disease, the persistent proteinuria group demonstrated a significantly higher risk of colorectal cancer compared with the proteinuria-free group (adjusted hazard ratio [aHR], 1.27; 95% CI, 1.13-1.42). Additionally, greater severity of proteinuria was associated with progressively increased colorectal cancer risk (aHR for overt proteinuria [+ 2 to + 4], 1.17; 95% CI, 1.05-1.29).

Conclusions: Changes in proteinuria status are significantly associated with colorectal cancer risk. Persistent proteinuria poses the highest risk, while transient proteinuria also elevates risk compared to individuals without proteinuria. Regular monitoring and management of proteinuria could potentially be beneficial in identifying individuals at higher colorectal cancer risk, suggesting its possible role as an indicator for targeted prevention strategies. However, further research, including randomized controlled trials, is necessary to confirm any causal relationship.