Secondary malignancies in mantle cell lymphoma patients—A nationwide population‐based study in Sweden

Introduction: With modern treatments, mantle cell lymphoma (MCL) patients may experience long-lasting remission resulting in a growing population of long-term survivors. Follow-up care includes identification and management of treatment-related late effects, such as secondary malignancies (SM). We conducted a population-based study to describe the burden of SM in MCL patients in Sweden. Methods: All Swedish patients with a primary diagnosis of MCL, aged >18 years and diagnosed between 2000 and 2017 were included, along with 6–10 matched population comparators. Patients and comparators were followed from twelve months after diagnosis/matching until death, emigration, or December 2019, whichever occurred first. Rates of SM among patients and comparators were estimated using the Anderson-Gill method (accounting for multiple events) and presented as hazard ratios (HR) with 95% confidence intervals (CI) adjusted for age, calendar year, sex and a time-dependent variable indicating the number of previous events. Results: Overall, 1452 patients and 13 992 comparators were followed for 6.6 years on average. Among patients, 230 (16%) developed at least one SM and a total of 264 SMs were observed. Relative to comparators, patients had a higher rate of SM, HRadj = 1.6(1.4–1.8) (Figure 1). Higher rates in patients were observed across all primary treatment groups: Nordic-MCL2 protocol (250 patients, HRadj = 1.4(1.0–2.0)), R-CHOP single (144 patients, HRadj = 2.0(1.3–2.9)), R-bendamustine (302 patients, HRadj = 2.2(1.7–2.7)), lenalidomide (16 patients, HRadj = 4.3(2.0–9.0)) (Figure 1), R-CHOP/Cytarabine (145 patients, HRadj = 1.6(1.0–2.5)), and ibrutinib (9 patients, HRadj = 4.8(1.2–18.7)) contrasted with comparators. Compared to Nordic-MCL2, treatment with R-bendamustine was independently associated with an increased risk of SM, HRadj = 2.0(1.2–3.3). Within patient groups, higher rates of SM were also seen with increasing age at diagnosis (p-trend < 0.001), for males (p = 0.006) and for patients with a family history of lymphoma (p = 0.009). Melanoma/skin cancer (n = 109, 41%), cancer of male genital organs (n = 38, 14%), digestive organs (n = 38, 14%), respiratory (n = 18, 7%), urinary tract (n = 17, 6%) and lympho-hematopoietic malignancies (excluding MCL, n = 17, 6%) were the most frequent SM. The research was funded by: The Swedish Cancer Society, project number: 22 2167 PI Ingrid Glimelius Keyword: Late Effects in Lymphoma Survivors No conflicts of interests pertinent to the abstract.