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Very Early Detection? British Group Gauges Public Interest in Embryo Testing for Cancer
Last fall, the Human Fertilization and Embryology Authority (HFEA), which regulates British fertility treatment and embryo research, posed a tough question to the public: Should embryo testing for cancer susceptibility genes be made widely available in the United Kingdom?
Preimplantation genetic diagnosis (PGD) can be used in in vitro fertilization to test embryos for conditions such as cystic fibrosis, Huntington disease, and hemophilia. But unlike these diseases, cancer susceptibility conditions have a lower penetrance (that is, not everyone with the faulty gene will develop the cancer); the occurrence of disease may have a later age of onset; and there is the possibility of preventive surgery, early detection, and effective treatment for some of these cancers in susceptible individuals.
Although the HFEA has already licensed PGD for conditions that may have one or two of these features—for example, for late-onset diseases such as Huntington disease—it is the combination of all three features that makes genetic susceptibility to cancer different from any conditions for which PGD licenses have previously been granted.
PGD is still seldom used in the United Kingdom, with only about 200 tests administered per year. This low rate is partly because the number of conditions for which it can be used is very limited and partly because it is extremely expensive. But the HFEA is concerned that they may receive a licensing application to use PGD for an inherited predisposition to cancer without having taken into account the views of the people the organization represents—the public, patients, the medical profession, and politicians. So the agency developed a document that discusses the considerations for testing for such conditions as familial adenomatous polyposis, retinoblastoma, multiple endocrine neoplasia 2, BRCA1 and BRCA2 mutations, and hereditary nonpolyposis colorectal cancer.
Reactions from pro-life organizations have been generally negative, with representatives talking about "a first step toward eugenics." Josephine Quintavalle, of the group Comment on Reproductive Ethics, said: "It's all about making endless decisions about who is better off dead. What we don't know is why some people with inherited susceptibility develop cancer and some don't, and that's the information we need."
But Shirley Hodgson, M.D., professor of cancer genetics at St. George's Hospital in London, who conducts research in inherited cancer susceptibility said, "Of course we are looking at a predisposition to cancer, and this does not mean that everyone who is predisposed will develop it. But some of the cancers involved are particularly nasty. Li–Fraumeni syndrome, for example, can cause a high risk of childhood cancers such as adrenal cancer, leukemia, and brain tumors. This is a very unpleasant condition in which it is hard to screen for cancers once a child is born.
"With regard to the later onset cancers, there are clearly good chances for better management, treatment, and screening options, say, 20 years on, so there is that option for avoiding testing for those genes in embryos. But lots of families have seen many relatives die of cancer at young ages and it is hard to convince them that this is not a serious genetic predisposition. They would often like to eradicate this from the family and remove the guilt of worrying that they may have passed it on to their children."
Breakthrough Breast Cancer, a leading U.K. research charity, welcomed the opportunity to comment on the issue. "We welcome a public debate on this complex and personal issue," said Sarah Rawlings, Ph.D., the organization's head of policy. "Women with a family history of breast cancer have told us that what is right for one person may not be right for another. Any potential parents need to be given the information and support they need in order to make informed choices."
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Other cancer charities were less enthusiastic, taking the view that there are enough problems with screening for cancer in adults without extending these obstacles to embryos. And, if licensed, the test will be a hugely expensive procedure, which leads to questions about the extent to which health care providers will make it available.
But Hodgson thinks that as long as the cancer susceptibility gene being tested for is highly penetrant, "say, over 60% risk of cancer developing in a mutation carrier," and the cancer is difficult to treat and serious (for example, gastric cancer), the benefits of allowing PGD for those who wish to have it would outweigh the risks.
However, she is firm about where the line should be drawn. "I think it would be a big mistake to start testing embryos for mutations that only alter susceptibility a little, by a factor of 2 or 3, for example," she said. "There are lots of such gene mutations with low penetrance for cancer and that would certainly imply a big slippery slope. So the main criteria for allowing PGD would be the serious nature of the cancer and the high risk, as well as difficulty with screening."
Ethicist Françoise Shenfield, M.D., from University College London, said, "In my view, PGD is acceptable in the case of multifactorial diseases, like cancer linked to BRCA, notwithstanding the uncertainties about the genetic predisposition and the epigenetic influence. It is, however, essential to take into account the severity of the illness and the effects on the quality of life of the future offspring, even though it is almost impossible to objectively assess the suffering and quality of life of any individual. But it is always advisable to test only embryos of couples who agree to know the results and who accept all the implications of the test."
Whatever the views of interested parties, the opportunity for the public to express their views before a decision is taken has been largely welcomed. The comment period on the issue closed in January. After considering reactions, the HFEA intends to develop and release a statement on the use of PGD in inherited susceptibility to cancer sometime this year.
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  A.L. Bredenoord, G. Pennings, H.J. Smeets, and G. de Wert Dealing with uncertainties: ethics of prenatal diagnosis and preimplantation genetic diagnosis to prevent mitochondrial disorders Hum. Reprod. Update, January 1, 2008; 14(1): 83 - 94. [Abstract] [Full Text] [PDF]
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