The research, which com drew on evidence that people with inflammatory bowel disease (IBD) are at an increased risk of colorectal cancer (CRC), primarily as the result of chronic intestinal inflammation.
Findings are reported in the study, “Crohn’s Disease Is Associated with the Risk for Thyroid Cancer,” recently published in the journal Inflammatory Bowel Diseases.
“Our results show that thyroid cancer is more prevalent in patients with IBD [inflammatory bowel disease] than the control group,” and the risk was “specifically” high in those with Crohn’s disease, Bo Shen, MD, with the Center for Inflammatory Bowel Diseases at the Cleveland Clinic Foundation, and colleagues wrote, according to a news release.
Another IBD subtype, ulcerative colitis (UC), was not found to be associated with a higher risk of thyroid cancer.
“It is recommended that patients with CD may need a close monitoring of thyroid diseases,” the researchers added.
To assess the risk factors associated with thyroid cancer, the team performed a case-control study using the 2012 National Inpatient Sample database. Researchers evaluated more than 28 million hospitalizations, 289,935 of which were related with IBD, and 315,145 of which were related with diverticulitis, cases that served as controls. (Diverticulitis results from inflammation in pouches that form in the large intestine and, typically, is a more mild than IBD.)
They found that IBD patients had a significantly higher risk for thyroid cancer compared to diverticulitis patients. Disease prevalence was comparable between men and women with IBD.
Looking at Crohn’s and ulcerative colitis separately, they also found that CD was highly associated with thyroid cancer, with CD patients more than two times more likely to develop this cancer than diverticulitis patients. Those with UC, in comparison, had about the same risk as people with diverticulitis.
Age was shown to be a protective factor in the presence of thyroid cancer, and a higher Charlson comorbidity index (an index that predicts one-year mortality for a patient who may have a range of comorbid conditions) was associated with the presence of thyroid cancer.
In a secondary analysis, researchers found that IBD patients overall had a higher prevalence of thyroid cancer compared with patients with two benign conditions — chronic constipation and atonic colon (loss of muscle strength).
More studies are needed to confirm these findings, since “to prove causation between IBD and thyroid cancer, analytical and prospective studies would be required,” the researchers concluded.