Embryo testing should be extended to check for faulty genes not guaranteed to cause disease, a report by the UK fertility watchdog recommends.
Embryos could be checked for inherited forms of breast cancer
The Human Fertilisation and Embryology Authority currently allows embryos to be screened for inherited diseases such as cystic fibrosis.
But it now says it would be "appropriate" to screen for susceptibility genes linked to cancer.
The recommendations will be considered for final approval on Wednesday.
A public meeting of the authority in Belfast will discuss the issue.
The HFEA's recommendation refers to three genes which cause cancer later in life - usually when people are in their 30s or 40s.
BRCA1 and BRCA2 are linked to an 80% risk of breast cancer and a 40% risk of ovarian cancer.
And mutations in the HNPCC gene are linked to an 80% risk of colon cancer.
Carrying these genes does not mean a person will definitely develop disease, but puts them at an increased risk.
Screening and treatment are available for the conditions.
The HFEA issues licences permitting fertility clinics to use the embryo screening technique, called pre-implantation genetic diagnosis (PGD).
Ten clinics are currently allowed to use PGD to test for inherited conditions - which an embryo carrying the faulty genes will certainly develop.
The procedure is used around 200 times a year.
PGD is already permitted for two inherited cancer conditions which affect young adults and children - familial adematous polyposis (FAP), a type of bowel cancer, and cancer of the retina.
The paper which will be considered at Wednesday's meeting reports that the HFEA's ethics and law committee recommends it would be appropriate, in principle, to extend the use PGD for cancer genes "because the features of the conditions are not incompatible with them being regarded as serious genetic conditions."
The HFEA launched a discussion document and public consultation on the issue last November, asking patients, affected families and doctors, MPs and members of the public their views.
Its chair Dame Suzi Leather, said the HFEA wanted to "balance the views and interests of all groups and move towards building a consensus."
However, some have expressed reservations about the idea of extending the use of PGD.
Dr Richard Kennedy, former chair of the British Fertility Society, said: "As the precision and success rates of PGD increase, so the choice of avoiding the threat and consequences of cancer becomes legitimate."
And Dr Sarah Rawlings, of Breakthrough Breast Cancer, said: "This is a complex and personal issue which we've discussed at length with women with a family history of breast cancer.
"They tell us that what might be right for one woman may not be the best option for another but it's important for parents to have access to information and support so they can make the right choice for them."
But Josephine Quintavalle, director of the group Comment on Reproductive Ethics, said: "PGD is currently nothing more than a weapon of destruction, aimed at the ruthless elimination of any embryo which does not conform to eugenic concepts of perfection.
"Given the permissive track record of the HFEA, it is hardly surprising that we now see them recommending the inclusion of lower penetrance cancer susceptibility on the growing hit list of undesirable genetic conditions to be put to the test.
"What should really be under the axe is not the unfortunate embryo but the HFEA itself, which has neither the moral training nor expertise to make these decisions on behalf of a just society."
Rachel Hurst, of Disability Awareness in Action, said: "If you say that it's OK to say that you can eliminate embryos which would lead to disabled people, you're saying that disabled people are not people.
"And you're saying that their quality of life is not worth living, which is discriminatory and extremely prejudicial."