Colorectal Cancer: RNA Biomarkers Detected in Wastewater for Population Surveillance
Researchers have detected RNA biomarkers associated with colorectal cancer in community wastewater, offering a potential new tool for population-level surveillance of the disease. The proof-of-concept study, published in the Journal of Epidemiology & Community Health, demonstrates the feasibility of tracking signals related to cancer burden through analysis of wastewater samples.
The study focused on identifying ribonucleic acid (RNA) biomarkers shed from tumors into sewage systems. Specifically, researchers targeted cadherin 1 (CDH1), a biomarker known to be associated with colorectal neoplasia, alongside a housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), for normalization. This approach builds on the growing field of wastewater surveillance, previously used to monitor public health threats like COVID-19, and adapts it to address cancer detection.
Traditional colorectal cancer (CRC) screening methods, such as colonoscopies and stool tests, rely on individual participation and can be limited by access and compliance. Wastewater surveillance offers a complementary approach, potentially providing a broader, population-level view of disease prevalence without requiring individual testing. What we have is particularly relevant as CRC rates are increasing among younger adults, where screening participation may be lower.
The research team collected wastewater samples from four residential sewer sheds in Kentucky: three identified as having a higher incidence of CRC and one serving as a control group. The high-incidence areas were determined by mapping patient addresses from a specialized care center and utilizing statewide cancer registry data. Researchers analyzed samples collected at three different times of day – morning, mid-morning, and early afternoon – to capture variations in biomarker levels.
Analysis revealed detectable levels of human RNA biomarkers in all samples. While GAPDH levels were consistent, CDH1 levels varied significantly between the clusters. The first cluster, which included patients from the specialized care center, exhibited the highest normalized CDH1/GAPDH values, reaching 20.0, aligning with clinical data. The second and third clusters showed lower levels at 2.2 and 4.0 respectively, while the control cluster had an average of 2.6. Notably, CDH1 levels spiked in the early afternoon samples from the first cluster.
The pronounced CDH1 signal in the first cluster suggests a potential correlation between wastewater biomarker levels and local disease burden, while researchers emphasize that this does not establish a definitive link. The control sewershed, while showing detectable CDH1, generally had lower levels, with two out of three measurements below 1.0, indicating low background levels.
Researchers acknowledge limitations in the study, including a limited number of samples, a single day of sampling, and the lack of statistical testing. They emphasize the demand for larger, longitudinal studies with more frequent sampling and stronger integration with cancer registry data to validate the findings and determine the sensitivity and specificity of wastewater biomarkers. Further investigation is likewise needed to address ethical and privacy considerations associated with this type of surveillance.
The study’s findings support the potential for wastewater surveillance to contribute to, rather than replace, traditional CRC detection methods. If validated, this approach could inform public health policy, optimize resource allocation, and guide targeted screening programs, particularly in areas with limited access to traditional screening services. Researchers plan to expand sampling sites and frequency in future studies to refine spatial mapping of CRC risk.