Positive FOBT Without Follow-Up Colonoscopy Linked to Increased Risk of Colorectal Cancer: JAMA
Sweden: Patients with a positive fecal occult blood test (FOBT) who skipped the recommended follow-up colonoscopy faced nearly four times higher risk of developing colorectal cancer. In contrast, individuals who underwent colonoscopy and received negative results had a markedly reduced cancer risk, even lower than that seen in the general population.
These findings underline the importance of completing colonoscopy after a positive FOBT and suggest that improving adherence to follow-up screening could significantly lower colorectal cancer burden in high-risk individuals.
A new study published in JAMA Network Open by Hanna Heyman and colleagues provides important insights into how colorectal cancer (CRC) risk differs depending on follow-up actions after a positive screening test. The research specifically examined outcomes in individuals who either had a negative colonoscopy or did not undergo the recommended procedure after testing positive in biennial FOBT screening.
The investigators conducted a large prospective cohort study within a population-based screening program in Stockholm-Gotland, Sweden, spanning 2008 to 2021.
The analysis revealed the following findings:
- The study included over 318,000 individuals aged 60–69 years invited for screening, of whom 14,873 tested positive for FOBT.
- Among those with positive FOBT results, 87.3% underwent colonoscopy.
- Nearly 75% of the colonoscopies performed showed no evidence of malignancy.
- Individuals with negative colonoscopy findings had a significantly reduced risk of colorectal cancer (SIR 0.52) compared to the general screened population.
- The reduction in colorectal cancer risk after a negative colonoscopy was more pronounced in men than in women.
- Participants who did not undergo follow-up colonoscopy after a positive FOBT had a markedly increased risk of colorectal cancer (SIR 4.21).
- Nonadherence to recommended colonoscopy was associated with substantially higher cancer risk, underscoring its clinical importance.
These findings clarify how colorectal cancer risk varies after screening outcomes. Individuals with negative colonoscopy may need less intensive follow-up, while those skipping colonoscopy after a positive FOBT form a high-risk group requiring targeted intervention.
The authors advocate for a more individualized, risk-based screening approach. Factors such as age, sex, and FIT levels could help refine follow-up strategies. With increasing pressure on colonoscopy services and expanding screening programs, prioritizing high-risk individuals may enhance efficiency and outcomes.
However, some limitations exist. The sample size was smaller than certain previous studies, with relatively few cancer events. Inclusion of both guaiac-based FOBT and FIT may affect applicability to current practice. Data on confounders beyond age were lacking, and although follow-up reached nearly 14 years, longer-term data would provide clearer insights.
Overall, the study reinforces that completing the diagnostic pathway after a positive screening test is crucial. It also identifies a clear opportunity for targeted strategies aimed at improving adherence and enhancing early detection of colorectal cancer.
Reference:
Heyman H, Saraste D, Jonsson H, Blom J. Colorectal Cancer Risk With Negative Colonoscopy or Nonadherence After Positive FOBT Screening. JAMA Netw Open. 2026;9(3):e262404. doi:10.1001/jamanetworkopen.2026.2404
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