Researchers have used genetic testing to reveal why some families are affected by several different types of cancer.
Scientists tested 1,162 patients with sarcoma, a rare cancer disproportionately affecting children and young adults, and found that more than half were born with at least one gene mutation known to increase cancer risk.
The team of researchers discovered that inherited genes already linked to breast, ovarian and bowel cancer, among others, were more common in sarcoma patients, putting them and their families at increased of other cancers too.
The discovery of the inherited risks will enable medics to better target treatments and provide screening and advice to families affected by cancer.
The Institute of Cancer Research’s Professor Ian Judson told the BBC: “We are going to need to think differently about inheritance.
“Sometimes you are confident there is something going on in the family - but standard patterns of risk might not fit.
“Now we can work out why that is because there may be two or three mutations going on.”
Sarcoma affects around 3,000 people in the UK each year and has low survival rates. It develops in the bones, muscles or soft tissues of the body.
While half of patients were found to have mutations or errors in at least one of the cancer genes tested, 20% had mutations or errors in more than one of the genes.
Those who had mutations in different cancer genes were more likely to develop cancer at a younger age than those with a single genetic mutation.
Scientists believe, therefore, that sarcoma is caused in some cases by several genetic mutations working together, rather than just one.
Judson added that when these mutations were discovered, medics could offer families genetic screening, leading to earlier detection and more effective treatments.
The study was conducted by The Institute of Cancer Research, The Royal Marsden NHS Foundation Trust and University College London Hospitals NHS Foundation Trust and published in The Lancet Oncology.