INCREASED INCIDENCE OF NEOPLASMS IN PATIENTS WHO DEVELOP SUSTAINED LEUKOPENIA DURING OR AFTER TREATMENT WITH 6 MP FOR INFLAMMATORY BOWEL DISEASE

Abstract

Purpose: Studies to date have not confirmed an association between neoplasms and IBD treated with 6MP. We have observed the occurrence of a number of neoplasms in IBD patients who developed sustained leukopenia due to treatment with 6MP. As a result, we sought to compare the incidence of neoplasms in patients who developed sustained leukopenia after treatment with 6 MP relative to patients treated with 6 MP who did not develop sustained leukopenia. Methods: A database representing the medical records of over 600 patients treated with 6MP for IBD at one center between 1969 and 2004 was searched. The patients were divided into 2 groups. The study group consisted of patients who developed sustained leukopenia, defined as a white blood cell count below 4,000 for greater than 2.5 weeks. The control group patients matched those in the study group for date of birth, sex and type of IBD (UC vs. CD). There were 3 matched controls for each patient in the study group. Data collected included disease location, cbcs, 6MP dosing information, malignancy history, family history and smoking history. Results: 31 patients developed sustained leukopenia, and of these, 8 developed neoplasms(26%). Median duration of leukopenia was 45 (17–1514) days. Of 93 patients without sustained leukopenia in the control group, 7 developed neoplasms (8%)(p = .017). The neoplasms in the study group were assorted, including 2 leukemias, 1 NHL but no colon cancers. 2 of the 7 neoplasms in the control group were colon cancers. There was no significant difference between the two groups in terms of family history, history of smoking and disease location. Cases also developed neoplasms significantly earlier than controls (log rank test = 4.34, p = .037)(Fig.1). [figure 1]FigureConclusions: There is an increased risk of neoplasms, in total number and in earlier onset, in patients who develop sustained leukopenia following treatment with 6MP. Perhaps, persistence of leukopenia for greater than 2.5 weeks should prompt discontinuation of 6MP.