Additional B-cell malignancies in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL)

Family and migration studies suggest a genetic risk of developing chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL). We hypothesized that CLL patients have an increased risk of additional clonally unrelated B-cell malignancies. To test this, we studied 467 CLL patients (2743 person-years (PYs)) at a single institution over 17 years. The incidence rate (IR) of any additional B-cell lymphoid malignancy was 10.9 per 1000 PYs (n = 30, 6.4%). Eighteen (4%) patients had a clonally unrelated B-cell malignancy (IR = 6.6 per 1000 PYs). Standardized incidence ratios (SIRs) were used to compare the incidence of additional clonally unrelated B-cell malignancies in CLL patients to the age- and sex-matched expected rates in the USA generated from the Surveillance, Epidemiology, and End Results (SEER) database. For the subset of 13 patients having data for comparison in the SEER database, the SIR was 5.41 (95% CI = 2.9, 9.3) which is supportive of our hypothesis.