Men have been found to be carriers of a genetic mutation which can cause ovarian cancer.
Fathers can pass on to their daughters the deadly cancer, which is the fifth-leading cause of cancer death for women, killing 14,000 a year in the US and more than 4,000 in the UK.
The genetic mutation, inherited from men’s mothers, raises their own risk of getting prostate cancer as well as threatening their daughters’ health.
Its discovery explains the mystery behind women being more likely to get ovarian cancer if their sisters have it than if their mother does. The common factor is their father, who has passed it on through the X chromosome.
The mutation, which has not been named, was discovered in a genetic study of 186 women with ovarian cancer done by Roswell Park Cancer Institute in Buffalo, New York.
Campaigners hope it will raise awareness that men can also pass on ovarian cancer, as they do with the BRCA gene mutation. This mutation, which famously caused Hollywood actress Angelina Jolie to have her ovaries and fallopian tubes removed to reduce her risk of ovarian cancer, is passed on by both men and women.
Dr Kevin Eng, who led the study, said: ‘Our study may explain why we find families with multiple affected daughters – because a dad’s chromosomes determine the sex of his children, all of his daughters have to carry the same X chromosome genes.
‘What we have to do next is make sure we have the right gene by sequencing more families.’
The researchers identified almost 3,500 grandmother and granddaughter pairs with ovarian cancer from health records, before sequencing the genes of 186 women.
They found women were twice as likely to get ovarian cancer from their grandmother on their father’s side, if they carried the genetic mutation, than from their mother’s mother.
The mutation is on the X chromosome, meaning their father passes it on from a grandmother to their granddaughter. The results could in future see men being screened to check their risk of carrying the defective gene.
It also explains why having a sister with ovarian cancer can quadruple a woman’ s risk of being diagnosed too. With more than 7,000 women a year being diagnosed with ovarian cancer, family history is the biggest predictor that someone is in danger.
Annwen Jones, chief executive of Target Ovarian Cancer, said: ‘A better understanding of the inherited genetic risk of ovarian cancer from the father’s side as well as from the mother’s side is vital for helping women to determine their individual risk of developing the disease and to make informed choices about preventative strategies, including surgery.
‘These findings, if borne out by further research, would represent a significant step forward in ovarian cancer prevention, saving thousands of lives.’
The study, published in the journal PLOS Genetics, found women inheriting the gene mutation from their father may be likely to develop ovarian cancer six years earlier than the average.
The defective gene is also associated with higher rates of prostate cancer in fathers and sons.
Dr Eng said: ‘This finding has sparked a lot of discussion within our group about how to find these X-linked families. It’s an all-or-none kind of pattern: A family with three daughters who all have ovarian cancer is more likely to be driven by inherited X mutations than by BRCA mutations.’