Simple program predicts who is most at risk of breast cancer
Cancer Research UK scientists have devised a user-friendly computer program, called the IBIS risk evaluator, which can give the most accurate estimate yet of a woman's chance of developing breast cancer.
The program, details of which are published in the current issue of Statistics in Medicine1, pulls together all the existing evidence on the causes and risk factors for breast cancer, such as age, family history and whether a woman has had children.
The risk evaluator, which is already in use in a few hospitals, could be available in every GP surgery to help doctors decide whether a woman needs reassurance or advice on prevention.
To use the program, a woman or her doctor answers questions on her family history of breast cancer - which of her relatives have been affected and at what age. This allows the program to work out whether the woman is likely to carry a high risk breast cancer gene, such as BRCA1 or 2, or whether she is likely to carry an as yet undiscovered lower risk gene.
Further questions investigate a woman's personal risk factors, such as her age, if she has had children, her height and weight, whether she is post-menopausal and if she has taken HRT. Her replies are then factored into the equation to produce a personalised risk profile.
Because the risk of breast cancer increases with age, the program gives a projected risk for the next ten years as well as over the woman's lifetime.
This risk is given as a percentage probability alongside the average risk for a woman of the same age in the UK. The majority of women can be reassured that their risk is similar to the population average.
Women who are at a high risk could join the IBIS-II prevention trial or be referred to a family cancer clinic. For all women, especially those at an increased risk, general advice can be given including guidance on weight loss, limiting HRT use and screening.
The research was led by Professor Jack Cuzick, Director of Cancer Research UK's Centre for Epidemiology, Mathematics and Statistics at Queen Mary, University of London.
Professor Cuzick says: "Breast cancer is already the most common form of cancer in the UK and it's on the increase. For many women, particularly those who have relatives affected by breast cancer, it's their biggest health concern."
Dr Jonathon Tyrer who also worked on the project comments: "The IBIS risk evaluator brings together everything we know about the causes of breast cancer to predict a woman's individual risk. We believe it will help doctors to deal with the growing number of the 'worried well' who visit their GP seeking advice on how they can avoid illness."
The program was originally devised to help find high-risk women who could take part in Cancer Research UK's breast cancer prevention trial, IBIS II2. However, the researchers quickly realised that the program had much wider potential.
Professor Cuzick explains: "We hope to develop this tool further to include risk factors for a variety of common diseases including heart disease and other cancers.
"One day it might be available in every GP surgery, perhaps even in every shopping centre, so people can find out their personal risk of various diseases and get a print out of what they can do to reduce their risk."
Cancer Research UK's Director of Clinical and External Affairs, Professor Robert Souhami, says: "There is no single cause of breast cancer but through research we have been able to find some of the most important risk factors.
"This program is a useful tool because it takes all the known risk factors into account and gives us an idea of who is most at risk. Knowing who is at risk is the first step towards preventing breast cancer."
- Statistics in Medicine23 (7)
- IBIS-II is a ten-year study involving 10,000 healthy women who are at an increased risk of breast cancer. Half of these women will be given a drug called anastrozole which has already been shown to be the most effective hormone treatment for breast cancer.