By Elodie Vaz | Published on March 25, 2026 | 4 min readColorectal
cancer remains a major public health issue. In the United States, more than
154,000 new cases are recorded each year, making it the third most common
cancer and the second leading cause of cancer-related death. This heavy burden
is largely due to late diagnosis, often when the disease is already advanced.
At the same time, a concerning rise in incidence among younger populations
underscores the need to rethink early detection strategies.
Detecting
the invisible
In this context, a study published on March 17 in the Journal of
Epidemiology & Community Health explores an innovative approach:
wastewater surveillance as an early warning tool for colorectal cancer.
Researchers are focusing on a promising suspect: CDH1 RNA, a biomarker
associated with the disease. In practical terms, the idea is to determine whether
biological signals found in human waste can reflect the health status of a
population at the community level.
A
territory-scale methodology
To test this hypothesis, researchers analyzed data from patients treated
between 2021 and 2023 at a tertiary care center in Jefferson County (Kentucky,
USA). They identified high-incidence areas (defined as more than four cases
within an 800-meter radius) and compared them with a control area where no
cases were recorded.
Wastewater
samples (175 mL) were collected from four catchment areas at three different
times of day. Analyses targeted two markers: CDH1, associated with cancer, and
GAPDH, used as a control for general cellular activity. Ratios between these
two biomarkers were then compared across the different areas.
Biological
signals correlated with high-risk areas
Results show that all samples contained detectable levels of both markers.
However, CDH1/GAPDH ratios varied across areas: 20 in the most affected group,
compared with 2.2 and 4 in the other high-incidence zones, and 2.6 in the
control area.
This
variability appears consistent with the distribution of clinical cases. The
group with the highest ratio also had a higher proportion of patients monitored
for colorectal cancer. However, researchers note potential biases, including
the possibility that residents from the control area may have been treated
elsewhere.
Limitations
but promising potential
The authors emphasize the exploratory nature of their work. Several
uncertainties remain, particularly the precise relationship between CDH1 levels
in wastewater and actual—diagnosed or undiagnosed—cases of colorectal cancer.
The small sample size and limited geographic scope also call for caution.
Nevertheless,
“the recent trend toward increasing colorectal cancer incidence in younger
populations highlights the need to improve public health approaches. While
existing screening methods such as colonoscopy and stool tests remain
effective, their reliance on individual adherence is problematic, especially in
communities facing structural and social barriers to healthcare,” the study
authors state in a press release.
Toward
sewer epidemiology?
Despite its limitations, the study opens new perspectives. “Detecting elevated
(colorectal cancer) markers in broader community areas, before high incidence
is recorded by tertiary care centers or state cancer registries, could help
target areas for practical and cost-effective community screening,” the
researchers suggest.
“This
approach could enable earlier diagnosis while identifying regions where the
likelihood of case detection is lower, thereby alerting clinicians in a timely
manner.”
Ultimately,
wastewater monitoring could complement existing systems by providing a
population-level view independent of individual screening behaviors. This
approach has already proven effective for infectious diseases and may now
extend to chronic conditions.
While
large-scale validation is still needed, this strategy points toward a shift in
screening paradigms—from reactive, individual-centered medicine to proactive,
population-based surveillance. In a context of increasing pressure on
healthcare systems, wastewater epidemiology could become a key tool for earlier
and more effective detection of silent diseases.
Read
next: CAR-T cells in colorectal cancer:
the challenge of solid tumors
About the Author – Elodie Vaz
Health journalist, CFPJ graduate (2023).
Élodie explores the marks diseases leave on bodies and, more broadly, on
human life. A registered nurse since 2010, she spent twelve years at patients’
bedsides before exchanging her stethoscope for a notebook. She now investigates
the links between environment and health, convinced that the vitality of life
cannot be reduced to that of humans alone.
