Chronic lymphocytic leukemia and secondary hematological malignancies: A nation-wide cancer registry study

Objective Chronic lymphocytic leukemia (CLL) treatment has changed dramatically, and landscape of second hematologic malignancies (SHM) evolves in the new era of targeted therapy. No data were available about the real‐world burden of SHM. Methods All 2631 patients with CLL in the Cancer registry of Norway registered 2003‐2012 were included. Results After median follow‐up of 6.6 years, 103 patients (4%) developed SHM. Diffuse large B‐cell lymphoma (DLBCL) was most common (n = 65; 63%). Median survival was 9.3 years (95% CI; 8.9‐9.8) in non‐SHM patients and 1.7 years in DLBCL, 0.8 years in Hodgkin lymphoma (n = 12), and 2.8 years in myeloid neoplasia (n = 15; 95% CI: 0.3‐2.6, 0.6‐2.9, and 0.4‐5.3, respectively; P < .001). Outcomes were poorest for SHM patients treated for CLL (HR 2.76, 95% CI 1.4‐5.5, P = 0.003). A higher proportion of men and younger age were found in SHM patients (median age 66 vs 72 years in non‐SHM; P < .001; men 68% vs 57%, P = .03). Myeloid neoplasia was rare (incidence rate 1/1000 person‐years; 95% CI: 0.6‐1.5) and tended to occur later than DLBCL in patients treated for CLL (median time from CLL to SHM 62 vs 45 months; P = .09). Conclusions SHM and especially myeloid malignancies were rare in chemoimmunotherapy era.