Genetic defect linked with cancer

Press, 15 August 1984, Page 6

Genetic defect linked with cancer

NZPA-AP Bar Harbour, Maine A childhood bone cdncer called osteosarcoma has been linked to the same genetic defect that causes an inherited children’s eye cancer, according to researchers. The discovery suggests that many forms of adult and childhood cancers might be caused by a kind of genetic defect, or mutation, that until now has been thought to occur only in inherited cancers, the researchers said. Webster Cavenee, one of the scientists who made the discovery, said officials at the National Institute of Health in Bethesda, Maryland, have given him S 4 million to begin searching immediately for this kind of defect in virtually every other kind of children’s cancer. Ray White of the University of Utah, who with Mr Cavenee was the first to discover the defect in the

eye cancer, said he already is looking for a similar link in breast and colon cancer. For several years researchers have known that certain genes, now called cancer genes, contributed to the formation of cancer. The discoveries involve entirely different genes that protect against cancer. In this case, cancer arises when these genes are absent or damaged. Messrs White. and Cavenee reported last year that they had identified this kind of defect in the eye cancer called retinoblastoma. The defect occurred in a gene on chromosome 13. (Humans have 23 pairs of chromosomes.) Earlier, this year Mr Cavenee reported finding a similar defect in a childhood kidney cancer called Wilms tumour. This defect was located on chromosome 11. Doctors had known for some time that children who survived retinoblas-

toma were at high risk of developing bone cancer in their teen-age years.

Mr Cavenee therefore looked at the bone cancer and found it was caused by a defect in the same gene that is reponsible for retinoblastoma.

Thaddeus Dryja, an ophthalmologist at the Massachusetts Eye and Ear Infirmary in Boston who had collaborated with Messrs Cavenee and White, then found the defect existed in bone cancer patients who had not had retinoblastoma.

The discovery suggests that this kind of defect in protective genes is not limited to inherited cancers.

The identification of such defects makes it possible to predict in some cases which children will develop disease.

It is now possible, for example, to test a foetus to determine before it is born whether it has inherited from its parents the genetic

defect responsible for retinoblastoma.

If, as the scientists hope, similar genetic defects turn out to be involved in many other cancers, it may ultimately be possible to screen for a variety of cancers. That does not necessarily mean that the cancers could therefore be prevented, but it does mean that people at risk for various cancers could, for example, watch their diet very carefully to keep their risk as low as possible. In the case of retinoblas-

toma, knowing which children are at risk will make it possible to catch the disease very early and thus treat it more effectively.

Retinoblastoma can now be cured about 85 per cent of the time, Mr Dryja said. Unfortunately, however, it is now becoming clear that many of those children who are cured will later be afflicted with bone cancer or some other form of cancer, he said. Retinoblastoma strikes some 400’American children a year, said Mr Dryja.