Philadelphia chromosome-negative myeloproliferative neoplasms (Ph- MPNs) are characterized by clonal myeloproliferation and somatic mutations. Major complications of Ph-MPNs are thrombosis, bleeding, transformation to myelofibrosis and leukemia. One important concern in the course of Ph-MPNs is risk of development of secondary solid cancers (SSC). In a large cohort of Turkish Ph-MPN patients, we aimed to determine the types and frequencies of SSC, to identify risk factors for SSC including role of cytoreductive therapies and to study impact of SSC on survival in Ph-MPNs.

1013 patients diagnosed with Ph-MPN from 1995 and 2022 under follow up at adult hematology sections of Istanbul Bakırköy Dr Sadi Konuk Hospital and Istanbul University Medical Faculty were included in this retrospective study.

Of the 1013 Ph- MPN patients enrolled in our study, 65, 46 and 37 patients were diagnosed with essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF), respectively. Patient clinical and laboratory characteristics are summarized in Table 1. Sixty-seven patients (6.6%) developed SSC, predominantly carcinoma (64.2%), non-melanoma skin cancer (23.9%), sarcoma (4.5%), and melanoma (3%). Median time to SSC diagnosis was 80.03 ± 60.5 months with no significant difference among Ph- MPN subtypes. Compared to patients with no diagnosis of SSC, patients with SSC were older at time of Ph- MPN diagnosis (63 vs. 54 years; p<0.001) and included a higher proportion of males (p=0.025). Ph- MPN patients with SSC and without SSC showed no significant difference for complete blood count parameters, spleen size, Ph-MPN diagnosis groups, driver mutation frequencies and follow-up time. Arterial thrombosis frequency was higher in patients with SSC (37.3% vs. 25.3%; p=0.030). SSC rates were 5.7% in patients not exposed to cytoreductive treatment and 5.3%, 4% and 2.1% with exposure to ruxolitinib, anagrelide, and interferon (IFN), respectively. A trend toward lower SSC rates was noted with IFN therapy (3% vs. 97%; p=0.066). SSC incidence was significantly higher in patients exposed to hydroxyurea (HU) as first-line monotherapy compared to other treatment groups (7.8% vs. 4.6%; p=0.046). Median OS in patients with SSC and patients with no diagnosis of SSC group were 273 months and 195 months, respectively. PV patients, who developed SSC, had significantly worse median OS compared to PV patients without SSC (Figure-1).

The strengths of our study are that it enrolls a larger patient population, includes PV, ET and PMF subgroups, separately examines development of SSC after MPN, has a long follow-up period and has multicenter design. In MPN patients, malignancy screening gains more importance for those aged ≥65 and males. Our study evaluated with data from previous studies suggest that increased risk of developing SSC in MPN patients may be associated with cytoreductive therapy. Further studies with more pateints are needed to determine whether Ph- MPN patients are predisposed to development of SSC independent of cytoreductive therapy, to better assess risk of HU or RUX in promoting SSC development in MPNs, and to elucidate the potential protective effect of IFN.