A large study has revealed “the strongest evidence yet” supporting genetic susceptibility to myeloid malignancies, according to a researcher.
The study showed that first-degree relatives of patients with myeloid malignancies had double the risk of developing a myeloid malignancy themselves, when compared to the general population.
The researchers observed significant risks for developing acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), essential thrombocythemia (ET), and polycythemia vera (PV).
“Our study provides the strongest evidence yet for inherited risk for these diseases—evidence that has proved evasive before, in part, because these cancers are relatively uncommon, and our ability to characterize these diseases has, until recently, been limited,” said Amit Sud, MBChB, PhD, of The Institute of Cancer Research in London, UK.
Dr Sud and his colleagues described their research in a letter to Blood.
The researchers analyzed data from the Swedish Family-Cancer Database, which included 93,199 first-degree relatives of 35,037 patients with myeloid malignancies. The patients had been diagnosed between 1958 and 2015.
First-degree relatives of the patients had an increased risk of all myeloid malignancies, with a standardized incidence ratio (SIR) of 1.99 (95% CI 1.12-2.04).
For individual diseases, there was a significant association between family history and increased risk for:
- AML—SIR=1.53 (95% CI 1.21-2.17)
- ET—SIR=6.30 (95% CI 3.95-9.54)
- MDS—SIR=6.87 (95% CI 4.07-10.86)
- PV—SIR=7.66 (95% CI 5.74-10.02).
Dr Sud and his colleagues noted that the strongest familial relative risks tended to occur for the same disease, but there were significant associations between different myeloid malignancies as well.
Risk by age group
The researchers also looked at familial relative risk for the same disease by patients’ age at diagnosis and observed a significantly increased risk for younger cases for all myeloproliferative neoplasms (MPNs) combined, PV, and MDS.
The SIRs for MPNs were 6.46 (95% CI 5.12-8.04) for patients age 59 or younger and 4.15 (95% CI 3.38-5.04) for patients older than 59.
The SIRs for PV were 10.90 (95% CI 7.12-15.97) for patients age 59 or younger and 5.96 (95% CI 3.93-8.67) for patients older than 59.
The SIRs for MDS were 11.95 (95% CI 6.36-20.43) for patients age 68 or younger and 3.27 (95% CI 1.06-7.63) for patients older than 68.
Risk by number of relatives
Dr Sud and his colleagues also discovered that familial relative risks of all myeloid malignancies and MPNs were significantly associated with the number of first-degree relatives affected by myeloid malignancies or MPNs.
The SIRs for first-degree relatives with 2 or more affected relatives were 4.55 (95% CI 2.08-8.64) for all myeloid malignancies and 17.82 (95% CI 5.79-24.89) for MPNs.
The SIRs for first-degree relatives with 1 affected relative were 1.96 (95% CI 1.79-2.15) for all myeloid malignancies and 4.83 (95% CI 4.14-5.60) for MPNs.
The researchers said these results suggest inherited genetic changes increase the risk of myeloid malignancies, although environmental factors shared in families could also play a role.
“In the future, our findings could help identify people at higher risk than normal because of their family background who could be prioritized for medical help like screening to catch the disease earlier if it arises,” Dr Sud said.
This study was funded by German Cancer Aid, the Swedish Research Council, ALF funding from Region Skåne, DKFZ, and Bloodwise.