Substantial familial risks of haematological cancers have been shown in a European study that found people who have a parent, sibling or child with a condition such as lymphoma have up to a 17-fold higher likelihood of being diagnosed with the same disease.
Younger age of diagnosis and the number of affected first-degree relatives were important factors in defining the relative risk of developing blood cancers, according to a study published in Blood .
In the most extensive analysis of familial risk of blood cancers to date, researchers identified 153,115 patients in a Swedish database diagnosed with a primary haematological malignancy.
They then quantified familial relative risks (FRRs) by calculating standardised incident ratios (SIR) in 391,131 first-degree relatives.
Most haematological malignancies showed increased FRRs for the same tumour type, with the highest risks being observed for mixed cellularity Hodgkin lymphoma (SIR=16.7), lymphoplasmacytic lymphoma (SIR=15.8) and mantle cell lymphoma (SIR=13.3).
The increases in family risk were 1.5-fold for acute myeloid leukaemia, 6.8 for essential thrombocythemia, 6.9 for myelodysplasia and a 7.7-fold increase in risk for polycythemia vera
For the B-cell tumours, relatives had two-fold increases in risk for diffuse large B-cell lymphoma (DLBCL), follicular lymphoma and multiple myeloma, and 5.6- 8.3- and 9.8-fold increases in risk for CLL, hairy cell leukaemia and nodular sclerosing Hodgkin lymphoma, respectively.
There was no evidence to support familial clustering of CML, myelofibrosis and T-cell neoplasms.
However, chronic lymphocytic leukaemia (CLL) was associated with an elevated familial risk of other B-cell tumours and myeloproliferative neoplasms.
Overall, familial cases represented 4.1% of all haematological malignancy diagnoses, which is higher than cancers of the nervous system (1.8%), kidney (2.8%) and pancreas (3.0%) but lower than those of the breast (8.5%), colorectal (10.1%) and prostate (15.3%) cancers.
Familial risk factors varied between cancers, with non-Hodgkin lymphoma, Hodgkin lymphoma and CLL having a greater risk among those who had a sibling with the disease, whereas others blood cancers were more likely to occur if a parent had been diagnosed.
“This information improves our understanding of the causes of – and potential inherited predisposition to – blood cancers and should inform the identification and characterization of genetic risk factors for blood cancer, as well as how we best clinically manage patients and their relatives,” said lead investigator Dr Amit Sud of the Institute of Cancer Research, London.
“The results should also encourage conversations among families, clinicians, and patients about familial risk,” he added.
Familial risk data may also have implications for genetic testing and screening initiatives for blood cancers, according to Dr Sud.
“Certainly there are a number of individuals, such as those with a relative diagnosed at a young age and or with more than one affected first-degree relatives, for whom counseling, genetic testing, and surveillance may be appropriate,” he said.
The analysis also has potential implications for the selection of related stem-cell donors used for the treatment of these malignancies, he added.