Thyroid Cancer in Inflammatory Bowel Disease

Background:
The incidence of malignancy is increased in patients with inflammatory bowel disease (IBD), with increased incidence of colorectal cancer in patients with ulcerative colitis (UC) prompting more frequent colon cancer screening. There is an increased risk in extra intestinal malignancies in patients with IBD. This study aims to bring attention to the risk of thyroid cancer (TC) in patients with IBD.
Methods:
This was a retrospective review of patients with ulcerative colitis or Crohn’s disease and a diagnosis of thyroid cancer. An IRB was approved to capture patients with these diagnoses between January 2020 and July 2023. The primary objective was to identify whether patients with UC or CD have a higher incidence of thyroid cancer than the general population. Secondary endpoint was to determine whether other variables are associated with a higher incidence of thyroid cancer.
Results:
Five patients were identified who had a diagnosis of both IBD and TC. Four patients had UC 1 patient had CD. Average age at time of IBD diagnosis was 47, average age at TC diagnosis 59 with mean time between diagnoses of 12 years. Four patients had co-morbidities of hypercholesterolemia, 2 with type 2 diabetes. Only 1 patient had a family history of thyroid cancer. Three of the patients had significant tobacco use history, 2 with no prior tobacco use. IBD involvement was limited to ileum in the 1 patient with CD. IBD involvement was either sigmoid or sigmoid and transverse in 2 and pancolitis in 2 patients with UC. Treatments prior to TC diagnosis were limited to none or Pentasa in 3 patients, with 2 patients having had colectomies due to refractory disease prior to TC diagnosis. Three of these patients had papillary thyroid cancer, 1 with medullary thyroid cancer and 1 with follicular carcinoma. None of these patients had or developed colorectal cancer.
Conclusions:
Current literature shows an increased overall risk of EICs in patients with IBD, in particular of some specific solid tumors. Among these include thyroid cancer with older age shown to be a protective factor. There was a slight propensity in these patients towards development of papillary thyroid carcinoma. This study also suggests development of TC to be unrelated to treatment regimens and perhaps related to obesity, co-morbidities or diet with underlying genetic predispositions. Studies with more power are needed to further understand the incidence of EICs in patients with IBD.