Individuals with chronic conditions are more inclined to attribute bowel habit changes to medication side effects rather than suspecting colorectal cancer despite it being a red flag, a new study has found.
Although screening practices and early diagnosis have improved, many colorectal cancer cases are diagnosed at an advanced stage, highlighting that symptoms can be challenging to recognise.
In fact, for patients with chronic conditions, overlapping symptoms or medication side effects may obscure warning signs. With multimorbidity and polypharmacy rising in older adults – those already at a higher risk of cancer – understanding symptom interpretation is increasingly important.
This study therefore examined whether people with common chronic conditions are more likely to attribute new-onset colorectal cancer symptoms to their existing medications.
Attributing colorectal cancer symptoms
The researchers conducted an online vignette survey among UK adults aged 50 and over, to explore how chronic conditions influence the attribution of colorectal cancer symptoms. Participants reviewed two symptom scenarios of new-onset rectal bleeding and change in bowel habit followed by questions on symptom attribution.
Responses from 1,287 participants were analysed, most of whom were women (61%) aged between 50 and 59 years (62%), with common conditions including obesity (31%), type 2 diabetes (25%), hypertension (25%) and arthritis (22%).
Participants with type 2 diabetes, obesity or arthritis were more likely to attribute changes in bowel habits to their medications, with 7-8% in these groups compared to 2-3% without these conditions.
Patients with diabetes had a two-fold higher likelihood of attributing change in bowel habit to medications, compared to those without the condition.
No chronic condition was associated with attributing rectal bleeding to medications.
Greater clinician and patient awareness needed
The researchers concluded that patients with common chronic conditions have a higher likelihood of attributing change in bowel habit to medications rather than colorectal cancer, and advised clinicians to be aware of this ‘alternative explanation’ bias.
They noted that their findings highlighted the need for clinicians to inform patients with chronic conditions of the overlap between medication side effects and potential cancer symptoms.
‘Patients should be encouraged to discuss any new or unusual symptoms promptly with their healthcare provider,’ they said.
Recognising the limitation of not having data on the specific treatments each patient was receiving, the researchers said future research should address this.
They added that future work should also explore the interplay between medications, symptom attribution and help-seeking behaviour using longitudinal and interdisciplinary approaches, which could determine causal relationships.
Such research would support the development of targeted communication strategies and diagnostic tools for older patients with multimorbidity, they concluded.
Reference
Ricciardi GE et al. Attribution of colorectal cancer symptoms to medications for pre-existing chronic conditions: a secondary analysis of a vignette study in England. Journal of Public Health. 2025;, fdaf014.
