Background: Second hematologic cancers in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) are well documented and include Hodgkin lymphoma, therapy-related acute myeloid leukemia/myelodysplastic syndromes, and transformation to diffuse large B-cell lymphoma. Although cutaneous T-cell lymphoma (CTCL) has been reported in patients with CLL, the incidence and comparison to expected rates are unknown. We evaluated the incidence of CTCL among patients with CLL or other non-Hodgkin lymphoma (NHL) subtypes using data from the Surveillance, Epidemiology, and End Results (SEER) Program. Methods: We searched the SEER 13 registries for patients with a diagnosis of CLL and NHL between 1992 and 2008. Among patients identified, we evaluated the incidence of CTCL. Results: Among 31,286 patients with CLL, the incidence of CTCL was not significantly higher in men than women: 104.2 (95% CI, 50.0–191.8) and 28.1 (95% CI, 3.4–101.3) per 1,000,000 person-years, respectively (P = 0.06). Among 97,691 patients with NHL, the incidence of CTCL was similar in men and women (97.9 [95% CI, 62.0–146.9] and 92.0 [95% CI, 56.2–142.1] per 1,000,000 person-years, respectively; P = 0.84). The incidence of CTCL among males with CLL (standardized incidence ratio [SIR], 3.0 [95% CI, 1.4–5.5]), males with NHL (SIR, 3.7 [95% CI, 2.3–5.5]), and females with NHL (SIR, 5.9 [95% CI, 3.6–9.1]) was significantly higher than expected in the general population (all P < 0.001). Conclusion: The risk of CTCL is greater in men with CLL than in the general population. In patients with NHL, both men and women are at greater risk for CTCL than in the general population.
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