A new online tool that could better predict the long-term risk of breast cancer returning in other areas of the body has been created.
The prognostic tool, known as CTS5 (Clinical Treatment Score post-5-years), could be used to decide which patients are at high enough risk of their cancer returning after receiving the standard five years of endocrine (hormone) therapy, and could therefore benefit from continuation of treatment.
The simple web-based calculator was developed by researchers at the Royal Marsden NHS Foundation Trust and Queen Mary, University of London, who said it could also be used to predict which patients are at low risk of recurrence.
This means they can avoid undergoing further therapy and its potential adverse side effects.
Researchers said that over the last three decades there has been a major increase in the rate of invasive breast cancer in western countries.
About 85% of patients are now diagnosed as oestrogen receptor (ER) positive, which means that the cancer grows in response to the hormone oestrogen.
Almost all of these patients are prescribed five years of hormone therapy after having standard treatment (surgery, chemotherapy, and/or radiation therapy), to lower the risk of the cancer returning.
However, hormone therapy can have significant side effects, including weakness of bone tissue and exacerbation of menopausal symptoms.
Oncologists, along with patients, have to decide after five years of hormone treatment whether extending this type of therapy is worthwhile and appropriate.
The team developed CTS5 after reviewing data from two previously published studies.
Together these provided information on 11,446 postmenopausal women with ER positive breast cancer who had received five years of hormone therapy (tamoxifen, anastrozole, or letrozole).
CTS5 was shown to be able to accurately separate women into groups of low, intermediate, or high risk of developing a late distant recurrence breast cancer after five years of hormone therapy.
The test identified 42% of women as who were sufficiently low risk so that extending hormone therapy would have been of very little value.
Co-lead researcher Mitch Dowsett (pictured), head of the Royal Marsden Ralph Lauren Centre for Breast Cancer Research and professor of biochemical endocrinology at the Institute of Cancer Research (ICR), said the calculator could improve clinical practice and benefit breast cancer patients by them avoiding potentially unnecessary extended treatment.
Prof Dowsett added: "Clinicians require expertise and the best tools to help them make crucial decisions on treatment for patients, decisions that can make a difference to patients' quality of life.
"This tool uses information that is already gathered in all patients, so could be easily used across the UK and globally at other centres."
Co-lead researcher Professor Jack Cuzick, from Queen Mary, University of London, said: "Hormone sensitive breast cancer is one of the few cancers where late recurrence is common, and predicting who is at high risk is particularly important so that they can continue hormone treatment.
"While our ability to predict this type of cancer is highly likely to improve in the future, we're providing a simple tool which is available now, and is easily used and well tested."
Details have been published in the Journal of Clinical Oncology.
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