Researchers have detected colorectal cancer-associated RNA markers in community wastewater, raising the prospect of using sewage surveillance to identify high-risk neighbourhoods and guide earlier targeted screening.
Wastewater surveillance may offer a new way to track colorectal cancer risk at neighbourhood level, opening the door to earlier targeted screening and public health intervention, researchers say.
A proof-of-concept US study has detected colorectal cancer-associated RNA biomarkers in community wastewater.
The researchers said this suggested sewage monitoring could eventually complement traditional bowel cancer screening program and help identify communities at elevated risk before cases were formally recorded through cancer registries or tertiary care centres.
Results have been published in the BMJ’s Journal of Epidemiology & Community Health.
“Our data provide proof of principle for a novel application of wastewater surveillance to track potential cancer burden,” the researchers wrote.
“We demonstrate that CDH1 is detectable in wastewater, potentially accelerating the development of this approach for epidemiological studies.
“Further investigation with additional samples and closer alignment with documented case activity will be necessary in future population-level CRC surveillance research.”
The research focused on detecting CDH1, a biomarker associated with colorectal neoplasia, in wastewater collected from four neighbourhood sewer catchments in Kentucky, including three areas linked to higher colorectal cancer incidence and one control area.
Using droplet digital PCR, investigators successfully identified human RNA and measurable levels of CDH1 in every wastewater sample analysed.
One cluster with known tertiary care colorectal cancer patients recorded markedly elevated normalised CDH1 expression compared with the control region, with average CDH1/GAPDH ratios reaching 20.0 versus 2.6 in the control catchment.
The researchers cautioned that the study was too small for statistical testing, but said the findings established biological feasibility for wastewater-based colorectal cancer surveillance.
“The findings of this study underscore the potential feasibility of expanding wastewater-based epidemiology as a community-level and population-level surveillance tool for CRC,” they wrote.
“By integrating environmental surveillance with biomolecular detection of CRC-associated markers, this study provides encouraging, though not definitive, preliminary data that help address the current limitations of CRC screening methodologies.”
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Wastewater monitoring became widely recognised during the covid pandemic as a tool for tracking infectious disease trends at community level.
The authors suggested the same principles could be extended to chronic disease surveillance, particularly for cancers that shed detectable biomarkers into stool.
They also highlight unresolved ethical and privacy considerations where a small number of diagnosed patients may contribute to detectable signals in a confined catchment area.
Future research priorities include larger-scale sampling, integration with cancer registry data, analysis of biomarker decay across sewer systems, and development of targeted intervention strategies informed by wastewater signals.
The researchers proposed that even annual sampling could help direct cost-effective screening resources toward underserved or high-risk communities.
While the technology remains experimental, they said their study represented one of the first demonstrations that human colorectal cancer-associated RNA markers could be identified in wastewater.
