Blood cancers

More data required on Australian rates of myeloproliferative neoplasms

Australian researchers have called for improved notification of genetic testing for myeloproliferative neoplasms (MPNs) into population-based cancer registries.

The call follows identification of changes in the incidence of polycythaemia vera (PV) and essential thrombocythaemia (ET) between 2003 and 2014,

As reported in the American Journal of Hematology, 8,604 Australians were diagnosed with one of the classic MPNs during the study period – an incidence rate of 23 cases per million population.

The research, led by Professor Peter Baade from Cancer Council Queensland, showed PV incidence had decreased by 8.8% per year in males and 7.8% in females over time.

In contrast, rates of ET had been increasing by 4.9% in males and a non-significant 3.4% in females.

Professor Baade told the limbic that one of the possible reasons for the trends was the changes in genetic testing – such as the JAK2 mutation – for the different cancers.

“There is a possibility that initially the PVs were actually overdiagnosed and carrying out the genetic testing is actually correctly diagnosing it,” he said.

“The role of genetic testing works the other way in terms of the ETs, because it increases the likelihood of diagnosing it.”

“Where the difficulty comes in about this is that given we don’t actually know the details about the prevalence of genetic testing, we can’t rule out the possibility that there might be real changes [in incidence] as well.”

The study found the overall five-year survival for MPNs was 80.8% and 10-year survival 67.7%. Five-year survival was higher in PV (91.1%) and ET (86.1%) than in primary myelofibrosis (50.1%).

Survival for all classic MPNs was about 50% worse in males than females.

Professor Baade, a biostatistician, said delayed diagnosis in men may explain the different survival rates.

“Males often have poorer survival across multiple cancer types because males often aren’t actually utilising their GP as much as women generally do.”

“We don’t actually get the details about the severity of disease when people are diagnosed which is another gap in the data. These are the kinds of questions which we can’t actually answer properly.”

He said he hoped that identifying some of the knowledge gaps about MPNs might motivate change and see more clinical characteristics and genetic information delivered into cancer registries.

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