Rare Disease Report

Young Myeloproliferative Neoplasms Patients Have Longer Survival than Older Counterparts

NOVEMBER 28, 2018
Rachel Lutz
Younger patients with myeloproliferative neoplasms (MPN)—that is, those patients under 40—are a steadily growing population and seem to have longer survival than their older counterparts, according to new findings.

Investigators from the Mayo Clinic in Rochester, Minnesota, found 361 young MPN patients from their mater institution database in order to understand survival trends in these patients. These patients were seen at the Mayo Clinic between 1967 and 2017. For reference, the center saw 3023 MPN patients between the time frame.

The investigators followed up with the MPN patients (seeing patients with polycythemia vera [PV] for 11.3 years on average; patients with essential thrombocythemia [ET] for 13 years; and patients with primary myelofibrosis [PMF] for 7.1 years) or until their deaths. They identified 79 patients with PV, 219 patients with ET, and 63 patients with PMF.

According to the investigators, oftentimes, the diagnosis of MPN occurs in patients who are in their 60s, and patients younger than 40 only make up between 2% and 8% of the MPN population. However, more recent studies have indicated that younger patients with MPN, especially those with PV and ET, can make up as much as 20% of the population.

The average age of the patients with PV was 32 years, the investigators said, and males made up about half the group. Patients younger than 40 presented less frequently with leukocytosis but more frequently with palpable splenomegaly compared with older patients with PV. Over the follow-up period, the investigators noted that instances of fibrotic transformation were 22% versus 25% versus 10% in those younger than 40, between 40 and 60 years, and over 60 years, respectively. Younger patients had a lower incidence of arterial events at diagnosis, but they had a higher incidence of venous thrombosis at any time during the course of their disease compared to older patients.

Patients with ET were an average age of 32 years, and about a third were males. Younger patients with ET had higher platelet counts than those between 40-60 years and those over 60. Over the follow-up period, the incidences of fibrotic progression were 16%, 16%, and 9% in the 3 age groups, respectively.

The average age of the patients with PMF was 37 years. Compared with older patients with PMF, younger patients had higher hemoglobin values, reduced transfusion dependence, higher platelet counts, fewer instances of thrombocytopenia, lower leukocyte counts, and less frequent leukocytosis. During the follow-up period, the investigators discovered leukemic conversions in 10% of patients, which is a similar rate found in the older patients.

The younger patients were also allocated to a “low-risk” category; “high-risk” patients were typically older.

Younger patients had longer median survival estimates than older patients across all disease subtypes, according to the investigators. For example, patients with PMF were still projected to have a median life expectancy of 20 years, compared with 8 years in patients between 40-60 years, and 3 years in patients over 60.

“When comparing MPN subtypes, PV and ET patients in all age tiers had a statistically significant survival advantage over their aged matched PMF cohorts,” the study authors wrote, adding that it was not entirely unexpected. They acknowledged that their findings highlight the importance of an accurate diagnosis, especially in young patients.

“Caution must thus be exercised in counseling and managing this population as historical ‘one-size-fits-all’ data fails to reflect the true natural history and disease biology in the young,” they concluded.

The study, titled “Myeloproliferative neoplasms in the young: Mayo Clinic experience with 361 patients aged 40 years or younger,” was published in the American Journal of Hematology.

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