To determine the risk of a wide range of second malignancies in patients with myeloproliferative neoplasms (MPNs), we conducted a large population-based study and compared the results to matched controls. From national Swedish registers, 9379 patients with MPNs diagnosed between 1973 and 2009, and 35,682 matched controls were identified as well as information on second malignancies, with follow-up until 2010. Hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated using Cox regression and a flexible parametric model. There was a significantly increased risk of any non-hematologic cancer with HR of 1.6 (95% CI: 1.5-1.7). The HRs for non-melanoma skin cancer was 2.8 (2.4-3.3), kidney cancer 2.8 (2.0-4.0), brain cancer 2.8 (1.9-4.2), endocrine cancers 2.5 (1.6-3.8), malignant melanoma 1.9 (1.4-2.7), pancreas cancer 1.8 (1.2-2.6), lung cancer 1.7 (1.4-2.2), and head and neck cancer 1.7 (1.2-2.6). The HR of second malignancies was similar across all MPN subtypes, sex, and calendar periods of MPN diagnosis. The risk of developing a hematologic malignancy was also significantly increased; the HR for acute myeloid leukemia was 46.0 (32.6-64.9) and for lymphoma 2.6 (2.0-3.3). In conclusion, our study provides robust population-based support of an increased cancer risk in MPN patients.

Infections are a common complication in patients with many hematologic malignancies, however whether patients with myeloproliferative neoplasms (MPN) also are at an increased risk of infections is largely unknown. To assess the risk of serious infections, we performed a large population-based matched cohort study in Sweden including 8 363 MPN patients and 32 405 controls using high-quality registers between the years 1992-2013 with follow-up until 2015. The hazard ratio (HR) of any infection was 2.0 (95% confidence interval 1.9-2.0), of bacterial infections 1.9 (1.8-2.0), and of viral infections 2.1 (1.9-2.3). One of the largest risk increases was that of sepsis, HR 2.6 (2.4-2.9). The HR of any infection was highest in primary myelofibrosis 3.7 (3.2-4.1), and significantly elevated in all MPN subtypes; 1.7 (1.6-1.8) in polycythemia vera and 1.7 (1.5-1.8) in essential thrombocythemia. There was no significant difference in risk of infections between untreated patients and patients treated with hydroxyurea or interferon-α during the years 2006-2013. These novel findings of an overall increased risk of infections in MPN

Background The reported incidence of Philadelphia‐negative myeloproliferative neoplasms (MPNs) differs substantially between previous reports, likely due to true regional differences in incidence and/or variations in the quality and coverage of the cancer registers. Objective We therefore assessed MPN incidence in Sweden during recent years using prospectively collected information captured in Swedish health registers. Methods Patients with MPNs were identified through the Swedish Cancer Register and Swedish Blood Cancer Register between 2000 and 2014. Information on the Swedish population was obtained from the Human Mortality Database. Crude and age‐standardized incidence rates of MPNs with 95% confidence intervals (CIs) were calculated. Results A total of 6281 MPN cases were reported to the Swedish Cancer Register and Swedish Blood Cancer Register during 2000–2014. The age‐standardized, to the Swedish population in 2000, incidence for all MPNs was 4.45 (95% confidence interval [CI] 4.34–4.56)/100 000 person‐years. The age‐standardized incidence for polycythemia vera was 1.48 (1.42–1.54), for essential thrombocythemia 1.60 (1.53–1.66) and for primary myelofibrosis 0.52 (0.48–0.56)/100 000 person‐years, respectively. The incidence rate of MPNs was substantially higher in the older compared to the younger age groups. The incidence increased during the study period, likely to do better reporting and increasing age of the general population. Conclusion The reported MPN incidences in our study, which were in the higher interval of previously published studies, are likely more accurate compared to previous reports due to the population‐based setting and high level of coverage in the Swedish Cancer and Blood Cancer Registers.