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Three cheers

Three cheers THEY have finally caught the nasty genes - which have been plaguing women with breast cancer -- red-handed. Breast cancer research took three significant strides this year with the isolation of the BRCA-2 gene, with scientists zeroing in on the relationship between cancer gene mutation and the type of cancer it causes and finally by the isolation of the gene responsible for the early onset of cancer.

The isolation of BRCA-2 by a team of researchers at the Institute of Cancer Research, London, is being seen as a path-breaking find in breast cancer research. Last year, when scientists had isolated BRCA-1, they immediately suspected the involvement of another troublemaker. Now, the hunt is on for yet another, a third gene.

Researchers report that defects in BRCA-1 account for almost half of the known breast cancer cases in Britain, while defects in BRCA-2 account for another third. "There may be yet another gene involved," say researchers. Even though, "the lifetime risk of contracting breast cancer for someone with abnormal BRCA-1 or BRCA-2 is about 80 per cent". Now that both genes have been isolated, scientists will be able to develop genetic tests to enable women with a farnily history of breast cancer, to find whether they are individually at risk.

On the other hand, pharmaceutical researchers have got a vital clue about the molecular mechanism by which breast cancer occurs. This will enable them to design more effective anti-cancer drugs, besides helping them to devise ways to repair the defective gene through gene therapy.

While the scientific community applauds the discovery of BRCA-2, they have yet another reason to celebrate. Simon Gavther and his colleagues at the Cancer Research Campaigns, Human Genetics group in Cambridge, have worked out a relationship between the position of BRCA- 1 mutations and the type of cancer they cause.

BRCA-1 is an example of a gene that causes two diseases. While the defective copies Of 13RCA-1 account for roughly half the inherited cases of breast cancer, the gene can cause ovarian cancer as well. Researchers say they can now predict whether a woman will develop both the diseases or just breast cancer. It will depend on determining the position of mutations on the BRCA-1 gene.

It is reported that more than 100 different BRCA-1 mutations take place along the length of the gene. Scientists have discovered that mutations in the third part of the cancer-causing genes usually mean breast cancer alone. In families afflicted by both the types of tumour, the mutations occur closer to the first part of the gene.

While nobody knows which protein the BRCA- I gene produces, or how the non-mutated form of this protein prevents cancer, scientists can take consolation from the discovery of a gene whose overactivity is supposed to promote breast cancer.

The work conducted by a research team headed by Patricia Steeg of the National Cancer Institute in US, is significant. Scientists discovered that the gene responsible for producing a protein called cyclin D, was "frequently overactive in early breast cancers but only rarely so in non-cancerous breast abnormalities".

Confirmation of this preliminary discovery by further research, shall pave the way for prevention of some breast cancers. For instance, drugs to slow down the activity of the gene will be useful for prevention of breast cancer in certain high risk cases.

Larry Norton at the Memorial Sloane Kettering Cancer Center in New York rightly says, "it is just the beginning and we do not have a specific therapy that is derived from this work". But these discoveries undeniably open up new vistas to arrest that lethal growth in the breast.

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