(ChemotherapyAdvisor) – Patients with chronic constipation had a significantly greater risk of developing colorectal cancer and benign neoplasms than those without chronic constipation, according to a study of a retrospective U.S. claims database reported during the American College of Gastroenterology’s 77th Annual Scientific Meeting, Las Vegas, LV.

Nicholas Talley, MD, PhD, of the University of Newcastle, Callaghan, NSW, Australia, and colleagues identified 28,854 patients with at least two diagnoses of chronic constipation from January 1999 to September 2011 in the database who were matched 1:3 with 86,562 controls by year of birth, sex, and region of residence. Those without chronic constipation “were defined as patients who had never been diagnosed for constipation and never had a prescription filled for a laxative during the entire observation period,” they noted.

Mean age of the patients in both groups was 61.9 years; 33.3% were male. The average observation period was 3.99 years. At 1 year, prevalence of colorectal cancer was 2.7% in the chronic constipation arm vs 1.7% in those without chronic constipation; benign neoplasms occurred in 24.8% vs 11.9% in each group, respectively.

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In the chronic constipation group, incidence per 1,000 patient years of colorectal cancer was 5.2 vs 2.9 for those without chronic constipation; incidence rate ratio (IRR) was 1.78. When adjusted for age, gender, index year, comorbidities, family history of malignancies, IRR was 1.59; and, when adjusted for number of colonoscopies, 1.20. Similarly, incidence per 1,000 patient years of benign neoplasms was 71.9 in the chronic constipation arm vs 26.6 in those without chronic constipation; unadjusted IRR was 2.70 and adjusted ratios were 2.60 and 2.06, respectively.

“This study demonstrates an association, not causation, between chronic constipation and both colorectal cancer and benign neoplasms,” said Dr. Talley “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.”

He 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 colorectal cancer would advance our understanding of prevention and management of these disorders.”

The study was supported by Takeda Pharmaceuticals International, Inc.

Abstract (select Oral & Posters, Browse by Number and select Abstract Number P866)