Patients with inflammatory bowel disease (IBD), especially those with ulcerative colitis, may be at a higher risk of developing thyroid cancer. Use of immunosupressant drugs was also found to possibly contribute to an increased risk for this cancer, according to researchers.
Their study, “Assessment of thyroid cancer risk in more than 334,000 patients with inflammatory bowel disease: a case-control study and a meta-analysis,” was published in the World Journal of Surgical Oncology.
IBD is considered a precancerous disease of colorectal cancer, also known as bowel cancer or colon cancer, and characterized by the growth of tumor cells in the colon or rectum (parts of the large intestine).
Researchers have previously found an increased risk of different types of cancer in IBD patients, including lung, skin, bladder and blood (leukemia).
Located in the front of the neck below the Adam’s apple, the thyroid gland is an important regulator of our body’s metabolism by producing several hormones involved in the digestion, heart function and growth processes, among others.
Deregulation of thyroid function is linked to numerous diseases and conditions, including auto-immune diseases, cognitive disability, and some types of cancer.
While some studies reported a higher risk of thyroid cancer in IBD patients, other failed to do so.
Lihong Cao, a researcher at Tianjin Medical University General Hospital in Tianjin, China, and his team analyzed the prevalence of thyroid cancer in IBD patients using two methods: a case-control study, where 1,392 IBD patients (1,022 with ulcerative colitis and 370 with Crohn’s disease) were compared with 1,392 controls (diagnosed with diverticulitis, an infection of the colon wall), admitted to the hospital between 1991 and 2000; and a meta-analysis, by searching different studies in online databases.
In the case-control study, IBD patients received 5-ASA medication (mesalamine), a medicine used to treat IBD (available under different brand names), or a similar treatment, but did not receive any kind of immunosuppressants or surgical therapy.
A history of smoking, drinking, ionized salt intake, radiation exposure, and a familiar history of thyroid cancer were analyzed.
Results showed that papillary thyroid carcinoma (PTC), a specific type of thyroid cancer, was more common in IBD patients than in controls.
However, no statistically significant association was found between thyroid cancer risk and IBD history. In fact, only a history of radiation exposure and family PTC history significantly correlated with a higher risk of PTC.
In the meta-analysis study, studies referring to IBD and thyroid cancer were searched in different online databases between 1998 and 2017. A total of 334,015 patients were included in the analysis.
In the meta-analysis, patients with total IBD or ulcerative colitis showed an increased risk of developing thyroid cancer, while Crohn’s disease patients did not.
Additional analysis revealed a link between immunosuppressive therapy intake and an increased risk of this type of cancer.
With these data, Cao observed a possible correlation between IBD, particularly ulcerative colitis, and a higher risk of developing thyroid cancer. Moreover, the study found that the inflammatory status associated with the disease and the use of immunosuppressants might be behind the development of this type of cancer.
“Based on the results of our case-control study and meta-analysis, we suggested that the risk of thyroid cancer probably elevated in patients with IBD, and this increase was more significant in its subtype ulcerative colitis,” Cao wrote in the study.
“Inflammatory response of IBD itself, use of immunosuppressant and other undefined factors contributed to the development of thyroid cancer. Well-adjusted and population-based studies should be conducted to verify our conclusion,” Cao added.