Several chronic inflammatory conditions are associated with an increased risk of lymphoma.
Whether this applies to inflammatory bowel disease is still unclear but of paramount interest, particularly in the safety evaluation of newer immunosuppressive drugs.
Reports also indicate a possible increase in the risk of leukaemia in IBD.
Dr Askling and colleagues from Sweden therefore assessed the risk of haematopoietic cancers in a large cohort of patients with IBD.
The investigative team performed a population based cohort study using prospectively recorded data.
The data was assembled from regional cohorts of IBD from 1955 to 1990 (n = 8028) and from the Inpatient Register of 1964–2000 (n = 45,060), with follow up until 2001.
The researchers included data from 47,679 Swedish patients with Crohn’s disease or ulcerative colitis.
|Haematopoietic cancers correspond to a 20% increased risk in ulcerative colitis and Crohn’s|
|European Journal of Gastroenterology and Hepatology|
Relative risks were expressed as standardised incidence ratios.
The research team observed 264 haematopoietic cancers during follow up, which corresponded to a borderline significant 20% increased risk in both ulcerative colitis and Crohn’s disease.
In ulcerative colitis, lymphomas occurred as expected with an incidence ratio of 1 (n= 87).
The researchers reported that myeloid leukaemia occurred significantly more often than expected with an incidence ratio of 1.8 (n= 32).
In addition, the team found a borderline significant increased lymphoma risk in Crohn’s disease with an incidence ratio of 1.3 (n= 65).
The team report that the results are essentially confined to the first years of follow up. and that proxy markers of disease activity had little impact on lymphoma risk.
Dr Askling’s team concludes, “On average, patients with IBD have a marginally increased risk of haematopoietic cancer.”
In ulcerative colitis, this is accounted for by an excess of myeloid leukaemia.”
“In Crohn’s disease, a modest short term increase in the risk of lymphoma of unknown significance cannot be excluded but any long term risk increase seems unlikely.”