Cancer Research UK scientists have developed a computer program that can predict genetic susceptibility to breast and ovarian cancer with unprecedented accuracy.

The Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm-BOADICEA-uses detailed family history to predict a woman's risk of developing cancer. It improves on previous programs because it takes into account genetic mutations besides those of the well-known BRCA1 and BRCA2 genes.

The researchers plan to offer BOADICEA to health professionals to help them pre-select women likely to be at high risk for further testing - and sparing others the anxiety of waiting for genetic test results. The program is described in the British Journal of Cancer.

Women with a strong risk of breast and ovarian cancer can be offered pre-emptive measures such as screening from an early age, preventive surgery (removing breasts or ovaries) or chemoprevention using drugs such as tamoxifen.

But the genetic tests needed to identify women as having genetic mutations in genes such as BRCA1 and BRCA2 are expensive. They can also be slow, causing considerable anxiety in the many patients who turn out not to be at high risk.

Professor Doug Easton of the Cancer Research UK Genetic Epidemiology Unit in Cambridge says: "We created the BOADICEA program in order to better target genetic testing towards only those women who are most likely to carry the mutations.

"BOADICEA works out a woman's breast and ovarian cancer risk using detailed information on her family history of cancer. The program calculates both her risk of carrying a particular cancer-causing mutation, and her overall risk of developing breast or ovarian cancer."

The program predicts cancer risk based on detailed genetic data gathered on 1,484 women with breast cancer and 156 families with multiple breast and ovarian cancer cases.

The team has just finished testing the program's accuracy by using it to predict high genetic risk of breast cancer in women whose family history was collected in the past by doctors. Comparing BOADICEA's answers to the results of genetic tests in those women has confirmed the program's strength.

Many genes are responsible for a woman's inherited risk of breast cancer. Most of these genes have only a small effect on their own, but working together they are a strong influence. The detailed family data the team have been put into BOADICEA means the program can take the influence of all of these genes into account - even those genes for which there is no biological test.

Easton adds: "BRCA1 and BRCA2 together account for under 20 percent of breast cancer clusters in families, so for a computer program of this nature to be accurate it is vital it can take other mutations into account.

"Having put the finished product through its paces by rigorously testing it, we have confirmed that it is more accurate than any such program created in the past."

The team is currently making BOADICEA more 'user friendly' and plans to make it available via the web to oncologists and geneticists.

SOURCE:
British Journal of Cancer, October 12, 2004
Cancer Research UK (http://www.cancerresearchuk.org)