NTU Reveals Colorectal Cancer Risk Indicator: Fecal Hemoglobin Levels Guide Colonoscopy Follow-Up Schedules

(Taipei, 13th - Reporter Chen Chieh-ling) Researchers from National Taiwan University (NTU) have analyzed data from nearly 4 million colorectal cancer screenings and found that individuals with higher fecal hemoglobin concentrations still face a colorectal cancer risk approximately 1.7 times higher than those with lower levels—even after polyp removal. This confirms that fecal hemoglobin concentration can serve as a reliable basis for scheduling follow-up colonoscopies.

Colorectal cancer is the second most commonly diagnosed cancer in Taiwan, with over 10,000 new cases and more than 5,000 deaths annually. However, it is a highly treatable cancer when detected early. The Ministry of Health and Welfare’s Health Promotion Administration provides free biennial quantitative immunochemical fecal occult blood tests (FIT) for individuals aged 45 to 74, and for those aged 40 to 44 with a family history of colorectal cancer.

This research has been published in Gastroenterology, a leading international journal in digestive medicine. Conducted by a team from NTU Hospital’s Department of Internal Medicine and NTU’s College of Public Health, the study used data from Taiwan’s national colorectal cancer screening program. It analyzed records from 3,929,387 individuals who underwent FIT screening between 2010 and 2015.

The study further included 89,771 individuals who tested positive for fecal occult blood, underwent colonoscopy, and had polyps removed, with an average follow-up period of 5.5 years. Dr. Han-Mo Chiu, Director of the Health Management Center at NTU Hospital, stated at a press conference that this is one of the few large-scale real-world studies globally, confirming that fecal hemoglobin concentration can be a crucial indicator for scheduling post-polypectomy colonoscopy follow-ups.

Approximately 400,000 people in Taiwan undergo colonoscopy annually under the National Health Insurance program. Dr. Chiu emphasized that an initial colonoscopy provides about 80% protection, but the remaining 20% risk must be managed through follow-up monitoring, making regular follow-up visits critically important. However, Taiwan exhibits an extreme dichotomy in follow-up behavior: one group avoids returning for check-ups despite medical recommendations, while another group, fearing cancer, schedules a colonoscopy every year.

Patients often worry: "Do I need to keep getting colonoscopies? How often should I be screened?" Currently, guidelines suggest that about 80% of patients fall into a low-risk category, with a recommended follow-up interval of 7 to 10 years, while about 20% are high-risk and should be monitored every 3 years. Cancers diagnosed within these recommended intervals are known as "interval cancers."

Dr. Chiu noted that interval cancers are the most undesirable outcome for both physicians and patients. About 60–80% arise from overlooked or incompletely removed lesions, while the rest stem from rapidly growing new lesions, often detected at an advanced stage. Precisely scheduling follow-ups to reduce interval cancer incidence is therefore crucial. Previous studies have shown that fecal hemoglobin levels reflect true intestinal conditions and can predict cancer risk.

This study focused specifically on individuals with positive fecal occult blood tests to evaluate whether fecal hemoglobin concentration could further refine colonoscopy follow-up scheduling. The results showed that even after polyp removal, those with higher fecal hemoglobin levels still had a 1.7-fold higher risk of developing colorectal cancer compared to those with lower levels.

For low-risk individuals, further stratification by fecal hemoglobin concentration allows for more precise follow-up scheduling. This approach could reduce colonoscopy demand by about 40% while further lowering cancer risk by approximately 7%. It enables a balance between efficient healthcare resource use and effective disease prevention—achieving both goals simultaneously.

Dr. Chiu warned that annual colonoscopies do not increase protective benefits. The bowel-cleansing agents used can disrupt the gut microbiome, taking 2–3 weeks to recover, thereby imposing unnecessary physical strain. He compared it to waking up every 30 minutes at night to check the gas valve out of fear of fire—not only does it not enhance safety, but it exhausts the mind.

Dr. Pi-Chun Chuang, attending physician in the Division of Gastroenterology and Hepatology at Hsinchu Branch of NTU Hospital, stated that only a very small number of extremely high-risk individuals require annual colonoscopies. Colonoscopy is not risk-free, especially for elderly patients on long-term anticoagulants or other medications that increase bleeding risk. The optimal follow-up schedule should always be determined through physician evaluation. (Editor: Kuan Chung-wei) 1150713