National Study Finds 2-Fold Risk of IBD Among Patients With MPNs

A large study of patients with myeloproliferative neoplasms (MPNs) is revealing that the chronic hematologic cancers are associated with a more than 2-fold risk of inflammatory bowel disease (IBD) in patients.

The researchers included over 8000 patients with MPN as well as more than 8000 sex- and age-matches controls, finding that patients with MPN were 2.4 times more likely to be diagnosed with IBD. They were 2.6 times more likely to develop ulcerative colitis and 2.4 times more likely to develop Crohn disease. These patients were also 40% more likely to have a prior diagnosis of IBD.

“Since we now find both an increased risk of IBD in patients with an already established diagnosis of MPN and an increased [overall risk] of IBD prior to the MPN diagnosis, converging causes of MPN and IBD must be considered,” wrote the researchers. “The development of these apparently disparate diseases in the same patient likely involve complex interactions between multiple environmental, treatment-related, and inflammation- and immune-mediated factors. Common genetic susceptibility may also contribute, and genome-wide associated studies indicate overlap in genes associated with both diseases (e.g., the JAK2 and STAT3 genes).

Over a mean follow-up time of 5.5 years, 80 patients with MPN were diagnosed with IBD, of which 37 had essential thrombocythemia, 28 had polycythemia vera, 14 had unclassifiable MPN, and 1 had myelofibrosis (MF). Meanwhile, 380 controls developed IBD.

According to the researchers, because more than half of patients can experience abdominal discomfort commonly caused by an enlarged spleen and/or treatment side effects, physicians may not readily attribute abdominal symptoms to IBD in some patients with MF, who often have severe disease and symptom burden.

“Our results pose intriguing questions about the casual pathways linking MPN and IBD, which may include genetic, treatment-related and immune-medicated factors,” wrote the researchers. “Moreover, it shows that abdominal symptoms in MPN patients may not only be caused by an enlarged spleen or treatment side-effects. Conversely, persistent leucocytosis and/or increased platelets in IBD patients may reflect concomitant MPN.”

Based on the rate of diagnosis, the overall rate of IBD per 1000 person-years in patients with MPN was 1.8, while the overall rate for controls was 0.8. Patients with MPN had double the 10-year risk of developing IBD than controls (0.8% vs 0.4%, respectively).

The researchers found that the risk of IBD increased with time, with risk significantly increasing within the first year (HR, 4.6; 95% CI, 2.8 to 7.6) as well as more than 5 years following MPN diagnosis (HR, 3.0; 95% CI, 2.1 to 4.2).

Reference

Bak M, Jess T, Flachs E, Zwisler A, Juel K, Frederiksen H. Risk of inflammatory bowel disease in patients with chronic myeloproliferative neoplasms: a Danish nationwide cohort study. Cancers. Published online September 21, 2020. doi:10.3390/cancers12092700