Patients with chronic constipation at increased risk of colorectal cancer, benign neoplasms

Study demonstrates association, not causation, researchers say

Patients with chronic constipation may be at increased risk of developing colorectal cancer and benign neoplasms, according to study findings unveiled today at the American College of Gastroenterology's (ACG) 77th Annual Scientific meeting in Las Vegas.

The study, "Risk of Developing Colorectal Cancer and Benign Neoplasm in Patients with Chronic Constipation," investigated the prevalence and incidence of colorectal cancer and benign neoplasms in 28,854 patients with chronic constipation (CC) and 86,562 controls without CC that were identified from a large retrospective U.S. claims database (January 1999-September 2011). Patients with at least two diagnoses of constipation were required to be 18 years or older and continuously enrolled in their health plan for at least one year following the study index date, which was the patient's first eligible diagnosis of constipation. Patients with diagnoses of irritable bowel syndrome or diarrhea were excluded.

Researchers found that: 

• Both colorectal cancer (CRC) and benign neoplasms are more prevalent in chronic constipation patients compared to a control population free from chronic constipation.
• Among the patients that were not previously diagnosed with CRC or benign neoplasms prior to their index date, and after controlling for potential confounding factors including age, gender, family history of malignancies, and other non-gastrointestinal comorbidities, patients with CC were more at risk to develop CRC or benign neoplasms.
• The risk of developing CRC was 1.78 times higher for chronic constipation (CC) patients and the risk of developing benign neoplasms was 2.70 times higher. After adjusting for potential confounding factors, which are potentially also associated with the CC conditions, the incremental risk of developing CRC and benign neoplasms remained "consistently high."

"This study demonstrates an association, not causation, between chronic constipation and both colorectal cancer and benign neoplasms" said co-investigator Nicholas Talley, M.D., Ph.D., of the University of Newcastle. "The postulated causal link between constipation and increased colorectal cancer risk is that longer transit times increase the duration of contact between the colonic mucosa and concentrated carcinogens in the lumen, such as bile acids or other carcinogens."

"The association between constipation and colorectal cancer deserves further exploration to better understand possible causal elements," said Dr. Talley. "Moreover, a review of the existing literature suggests prospective cohort studies have not identified this association. Thus, the findings may reflect recall bias."

"In this study, patients with chronic constipation were found to be at increased risk of developing colorectal cancer and benign neoplasms, said Dr. Talley. "Although chronic constipation is considered a relatively benign disease, practitioners should be aware of this potential association to monitor and treat accordingly," said Dr. Talley. "We encourage anyone with questions related to their condition to talk to their health care professional so that the specific health needs of each patient can be balanced with the risks and benefits of medications."

He also noted that further research is warranted to evaluate whether patients who have their constipation well controlled are at lower risk of developing CRC and benign neoplasms. "Longitudinal prospective studies to understand the causal relationship between chronic constipation and CRC would advance our understanding of prevention and management of these disorders."