New test offers hope of easy and affordable screening for hereditary breast cancer genes.(Brief Article)

2002 APR 11 - (NewsRx.com & NewsRx.net) -- Researchers at the Nottingham Breast Unit in the U.K. have developed an easy and affordable way of screening families for underlying hereditary genetic mutations that predispose them to developing breast cancer, the 3rd European Breast Cancer Conference in Barcelona (March 2002).

By testing samples from either two family members affected by breast cancer or from one family member with two tumors, the new test can indicate the presence of mutations in breast cancer genes in 50% of cases, and possibly even more. Once the test has given this indication, doctors can then go on to carry out genetic mutation analysis in only those families where the test has shown a mutation is most likely to be present, and so cut costs by avoiding unnecessary analyses.

Jose Cid, who carried out the research while he was a clinical research fellow at the Breast Unit, told the conference that an added advantage of this test is that it can be carried out on tumor material stored from previous operations, which enables families to be tested for the presence of a gene mutation when the relative with cancer has already died.

"At present, women who have a high chance of carrying a gene mutation are seen in the family history clinic, where they are offered gene testing only after a full mutational analysis has been done first in the blood of a living, affected relative," he said. "This is time-consuming and expensive. Our alternative procedure requires analysis also in relatives, but this can be done in tissue stored from an operation sometimes carried out many years ago, and it is quick, easy and affordable."

Cid recruited 67 families who were expected to be at high risk of developing hereditary breast cancer from the strength of their family history. He did not know in advance whether or not they had mutations in the breast cancer genes BRCA1 and BRCA2.

He analyzed samples from two tumors per family (the majority of families with tumors in two relatives, and a few with two tumors in one person) to see whether there was a loss of genetic material close to the BRCA genes and whether the same loss was seen in the same place in both tumor samples. All genes and DNA material come in pairs, and when genetic material from one half of a pair is lost in a cancer cell it is called loss of heterozygosity (LOH). Losses of portions of genetic material occur at random in all cancers (because genetic material is unstable in cancer), and so there is always a "background" level of LOH found in sporadic (i.e., nonhereditary) cancers. ...