Using a proof-of-concept approach, researchers demonstrated that colorectal cancer-associated RNA biomarkers, including CDH1, can be detected in community wastewater.
Research: Use of wastewater for population-level colorectal cancer surveillance: A future research agenda. Image credit: Siyanight / Shutterstock
A proof-of-concept feasibility study Journal of Epidemiology and Community Health reveals a feasibility-based approach to detect colorectal cancer (CRC)-related signals at the community level through wastewater monitoring systems.
Researchers have for the first time detected specific human ribonucleic acid (RNA) biomarkers associated with colorectal tumors in community wastewater using a biomarker used in a sensitive multi-targeted fecal RNA (mt-sRNA) assay used for early detection of colorectal cancer in adults aged 45 and older.
The detection of biomarkers such as cadherin 1 (CDH1) highlights the feasibility and potential utility of this method to complement traditional screening and provides future research avenues for community-driven public health interventions and targeted prevention programs, especially as colorectal cancer incidence increases, especially in younger populations.
Limitations of conventional colorectal cancer screening methods
CRC remains a major health threat, and early detection is important to improve outcomes. Traditional screening with colonoscopies and stool tests relies on individual participation, which is often limited in low-resource settings.
Wastewater surveillance offers a potential supplementary population-level approach, detecting RNA biomarkers shed in wastewater to explore patterns associated with community-level CRC burden, rather than directly measuring individual risk. This approach could enable broader, more equitable, community-focused CRC screening and population-level risk monitoring by potentially reducing reliance on individual compliance.
Previous studies have focused on anticancer drugs or nonspecific mitochondrial deoxyribonucleic acid (DNA) in wastewater. Targeting CRC-specific biomarkers may enhance early detection in future studies and complement existing prevention strategies.
Study design and wastewater sampling methods
In this retrospective study, researchers assessed the feasibility of detecting human RNA biomarkers of colorectal cancer in neighborhood-level wastewater, with the aim of tracking signals that may be related to colorectal cancer burden in local communities.
Researchers used traditional methods to select RNA biomarkers informed by multitarget fecal RNA assays for exploratory population-level colorectal cancer surveillance. They collected wastewater samples from four residential wastewater facilities, three high-incidence CRC clusters, and one control area.
RNA extracted from the samples was subjected to digital polymerase chain reaction (PCR) to quantify biomarker expression. These biomarkers include the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and CDH1, which is associated with colorectal tumors.
The research team collected colorectal cancer data from specialty care centers from 2021 to 2023. They then mapped patients’ residential addresses to identify areas with high rates of colorectal cancer. The first two clusters represented areas with four or more cases within a half-mile of the center.
Researchers used demographics consistent with statewide cancer registry data to select a third cluster representing a high-incidence area that did not completely overlap with the care center cluster.
The fourth cluster (controls) included sewer huts with no confirmed cases in the specific dataset used, but residents may still be diagnosed or treated for CRC outside of these sources.
To complement this, the researchers analyzed state-level cancer registry data from 1995 to 2018 and calculated sex- and age-standardized colorectal cancer rates across Kentucky census tracts. Using Getis-Ord Gi* spatial statistics, researchers identified additional high-incidence areas and confirmed three CRC clusters to support management sewer tailing selection.
All sewage facilities were located in residential areas. The researchers used the Environmental Systems Research Institute’s (ESRI) Business Analyst platform to obtain demographic data. They collected wastewater samples from the manholes of each sewer shed at three points in the day: mid-morning, mid-morning, and early afternoon to improve coverage.
The sewer system included both an integrated stormwater/wastewater system and a separate sanitary line. These samples captured patterns of RNA biomarkers over time and across communities, but sampling was limited to one day and no statistical testing was performed on a small number of samples, thus supporting wastewater surveillance for CRC monitoring.
Detection of CRC biomarkers in wastewater
Wastewater analysis confirmed the presence of human RNA biomarkers at detectable levels in all samples. GAPDH averaged approximately 52 copies per microliter, confirming consistent RNA extraction.
Colorectal tumor-associated CDH1 normalized to GAPDH was generally lower in morning and mid-morning samples. In contrast, CDH1 levels spiked in early afternoon samples from the first cluster.
Normalized mean CDH1/GAPDH values ​​differed between clusters. The researchers found levels of 20.0 in the first cluster, 2.2 in the second cluster, and 4.0 in the third cluster, compared to a level of 2.6 in the control cluster.
The first cluster included known patients from a specialized treatment center and showed the highest CDH1 signal, consistent with clinical data. In control sewers, CDH1 remained detectable but generally lower, with two out of three measurements below 1.0, indicating low background levels. The prominent CDH1 signal in the first cluster suggests, but has not been established, that wastewater monitoring may reflect the underlying local disease burden.
Implications for public health and colorectal cancer monitoring
The results of this study demonstrate that CRC-associated RNA biomarkers, including CDH1, can be detected in community wastewater, supporting a viable but preliminary and hypothesis-generating community-level epidemiological surveillance approach.
Initial evidence suggests that non-invasive monitoring can potentially contribute to, rather than replace, traditional colorectal cancer detection and support population-level risk assessment.
By identifying high-risk areas with minimal patient participation, this method, if validated, could ultimately inform public health policy, optimize resource allocation, and guide targeted screening programs.
Future research and validation needs
Future studies should expand the number and frequency of sampling sites, validate the sensitivity and specificity of wastewater biomarkers, integrate findings with cancer registry data to improve spatial mapping of colorectal cancer risk, and carefully address ethical and privacy considerations.
Larger, longer-term studies with repeated sampling and stronger associations with confirmed colorectal cancer incidence are essential to determine efficacy, sensitivity, specificity, and real-world applicability. These steps will help establish a robust, evidence-based framework for community-level colorectal cancer monitoring and support the development of targeted public health interventions.
