Effect of first-line treatment on second primary malignancies and Richter's transformation in patients with CLL

This study aimed to assess the frequency of and the contributing factors for second primary malignancies (SPMs) and Richter's transformations (RTs) following first-line treatment of chronic lymphocytic leukemia within four phase II/III trials of the GCLLSG evaluating fludarabine (F) vs F+cyclophosphamide (FC), chlorambucil vs F, FC without or with rituximab, and bendamustine+R (BR). Among 1458 patients, 239 (16.4%) experienced either an SPM (N=191) or a RT (N=75). Solid tumors (N=115; 43.2% of all second neoplasias) appeared most frequently, followed by RTs (N=75; 28.2%). Patients showed a 1.23-fold increased risk of solid tumors in comparison to the age-matched general population from the German cancer registry. Age>65 (hazard ratio (HR) 2.1; P<0.001), male sex (HR 1.7; P=0.01), co-morbidities (HR 1.6; P=0.01) and number of subsequent treatments⩾1 (HR 12.1; P<0.001) showed an independent adverse prognostic impact on SPM-free survival. Serum thymidine kinase>10 U/l at trial enrollment (HR 3.9; P=0.02), non-response to first-line treatment (HR 3.6; P<0.001) and number of subsequent treatments⩾1 (HR 30.2; P<0.001) were independently associated with increased risk for RT.