Embryos should not be screened for cancer genes, Jennifer Swift argues

Suppose you had seen your mother or sister sicken and die of breast cancer. Suppose you also knew that her fate was due not to chance mutation, but to one of the relatively rare cases of breast cancer - an estimated five to ten per cent - arising from a defective gene, and that you had inherited this gene yourself (as a consultation document from the Human Fertilisation and Embryology Authority (HFEA) says). Wouldn't you be eager to take steps to do what you could to prevent your children from being born with a genetic predisposition to develop breast cancer?

Thanks to breakthroughs in genetics and reproductive technology, this now appears to be possible. Scientists have identified the two genes linked to most cases of inherited breast and ovarian cancer, BRCA1 and BRCA2. Thus a woman can learn from a blood sample whether she carries a mutated copy of one of these genes and is prone to develop cancer herself.

Fertility doctors have discovered how to remove one or two cells from a very early human embryo and analyse its genes to see whether the embryo has mutations. This technique, known as pre-implantation genetic diagnosis (PGD), can be combined with in vitro fertilisation technology so that a couple who know they are carriers of a genetic disease can avoid having children with the disease.

The woman is given drugs to stimulate the release of ten to 12 human eggs at once. These eggs are collected and fertilised with the man's sperm, then the resulting embryos are studied to see which ones carry the genes for the disease. Only the embryos that are free of the disease are placed in the woman' s womb to develop and be born.

In the UK, any new use of PGD technology must first be authorised by the HFEA. So far, it has permitted couples to use PGD only to avoid having children suffering from diseases such as cystic fibrosis or haemophilia. These are early-onset diseases, handicapping the child from birth, and highly penetrant, meaning that a child carrying the trait is virtually certain to develop the disease. Therapies for treating them are currently very limited.

But the HFEA expects that very soon couples from families in which there is an inherited susceptibility to cancer (genes are known for familial forms of bowel and thyroid cancer, as well as breast cancer) will ask the authority to license the use of PGD to screen out embryos carrying predispositions to these cancers. So the HFEA is now carrying out a consultation, "Choices and Boundaries", which seeks the public's views on the issue.

Many in Britain, including some in the Churches, will welcome this possibility. Surely the only possible objection to it is the belief that human embryos have full moral personhood from conception, and must be given the opportunity to develop regardless of their genes. I acknowledge that the moral status of the human embryo is a very serious issue, but there are other grounds for objecting to this widening of embryo screening.

First, as the HFEA notes, unlike the conditions for which PGD is already authorised, only a proportion of those who inherit familial cancer genes actually develop cancer, and they will do so as adults. The risk can be high - it is estimated that a woman with the BRCA1 gene has an 80 per cent chance of developing breast cancer.

But it must be also borne in mind that survival rates from breast cancer have been steadily growing, and, if it is caught in the early stages, they are now approaching 90 per cent. Also, the close monitoring that BRCA carriers receive should increase the likelihood of detecting tumours before they have spread to other parts of the body (as Cancer Research UK says).

Recent studies suggest that breast cancer arising from a mutation in a BRCA gene is no more likely to kill a woman than a breast cancer arising by chance (according to M. Al Tamer in Annals of Surgical Oncology). Some women who are uncomfortable with watchful waiting have even opted for surgical removal of their breasts, which almost eliminates the risk of developing breast cancer.

Bilateral mastectomy is an operation that no woman would welcome, but is that such a tragedy that it would be better never to have been born? Also, IVF itself is not risk-free, even if the media generally fail to report this. Multiple pregnancies, with their concomitant risks of handicap or stillbirth, are much more common when in vitro fertilisation is used, and even singleton IVF babies are more likely to have a low birth weight and even to die soon after birth (Michael Le Page, New Scientist, 25 June 2005).

The IVF process is psychologically stressful for both parents, and the drugs used pose both short- and long-term health risks, possibly also including a greater chance of the woman's developing breast or ovarian cancer (according to Judy Norsigien at www.gene-watch.org).

If the HFEA licenses PGD so that parents can screen out embryos carrying traits that are as treatable as breast cancer, the authority might find it hard to draw the line and stop anxious parents from using the technique to prevent the birth of children affected by virtually any condition with a genetic link, whether it is adult-onset diabetes, schizophrenia, or even shyness.

Such parents would have to be well off in order to afford the expense of PGD plus IVF, but there is still a serious risk that the same sort of people who can afford to send their children to expensive schools will have their embryos routinely screened for "defects", and that this will increase the pressure on parents of all social classes to get as close as they can to having "perfect" children, too. We can see this process already under way in abortion, which is permitted right up to birth on the grounds of "serious handicap", a term left to the parents and two doctors to define.

A eugenic utopia is not more desirable because it arises from social pressures instead of state coercion.

Jennifer Swift is a writer on bioethics and co-convener of the Oxford University Genetics Forum.

The HFEA consultation is at www.hfea.gov.uk/consultations . The deadline for responses is 16 January.