A population level analysis of second hematological malignancies in chronic lymphocytic leukemia/small lymphocytic lymphoma survivors in the era of targeted therapies.

With improvement in survival after chronic lymphocytic leukemia (CLL) diagnosis, the real-world burden of second hematological malignancies (SHM) has not been comprehensively assessed in recent era. We analyzed risk, incidence, and outcomes of SHM in CLL patients between 2000 and 2019 using SEER database. CLL patients had greater risk for hematological malignancies than general population [SIR, standardized incidence ratio (95% CI):2.58 (2.46-2.70); p < 0.05]. The risk for subsequent lymphoma increased by 1.75 folds in 2015-2019 compared to 2000-2004. The duration, after CLL diagnosis, of maximum risk for SHM decreased as 60-119 months for time-period 2000-2004, 6-11 months for 2005-2009 to 2-5 months for 2010-2014 and 2015-2019. Incidence of SHM was 2.5% in CLL survivors (1736/70,346) with lymphoid SHM being more common than myeloid SHM, and DLBCL being the most common pathology (n = 610, 35% of all SHM). Male sex, age ≤65 years at CLL diagnosis, and chemotherapy treatment were associated with higher risk for SHM. The median gap between CLL and SHM diagnoses was 46 months. The median survival for de-novo-AML, t-MN, CML, and aggressive NHL was 63, 86, 95, and 96 months respectively. Although SHM remains rare, there is increased risk in recent era, likely due to improved survival in CLL patients, necessitating active surveillance strategies.