New breast cancer test is better at diagnosing need for chemotherapy
2 July 2013
A new genetic test can better determine the likelihood of recurrence of a common form of breast cancer and help decide on the need for chemotherapy.
A team at The Institute of Cancer Research, London, The Royal Marsden NHS Foundation Trust and Queen Mary University of London developed the new test, called PAM50. It indentifies more women with the highest risk of their breast cancer returning, with fewer women classed as at intermediate risk.
The test can help doctors identify with greater certainty the women who will have the most potential of benefitting from chemotherapy, while letting others avoid unnecessary treatment.
Currently, a test called Oncotype DX can assess the likelihood of a patient’s breast cancer returning, but it costs more than £2,000 per patient to be administered privately and samples must be sent to the US to be processed. This test also identifies a large portion of women as having ‘intermediate risk’, making a doctor’s decision of whether chemotherapy will help more difficult.
Professor Mitch Dowsett, Professor of Biochemical Endocrinology at The Institute of Cancer Research and Head of Biochemistry at The Royal Marsden, said: “Chemotherapy is often used after surgery to reduce the risk of a patient’s breast cancer coming back, but the side-effects are significant and some women will not see any benefit. While the current test is useful for both patients and clinicians to help them decide whether chemotherapy is needed, it’s expensive and not available locally.
“Our study found that the PAM50 test is more effective than other methods at providing the information to exclude breast cancer patients from unnecessary chemotherapy, and has the potential to be done more quickly. For each sub-group of breast cancer the PAM50 test added significant information beyond that of the standard clinical treatment score and the Oncotype DX score combined.”
Professor Alan Ashworth, Chief Executive of The Institute of Cancer Research, said: “The great strides that have been made in breast cancer treatment have resulted in a large rise in survival from the disease, but some women receive treatment which can be arduous while receiving no benefit. This test will improve doctors’ knowledge of who might benefit, allowing more women to make better informed decisions on their treatment.”
Breakthrough Breast Cancer’s Director of Research Julia Wilson said: “The PAM50 test has been proven to be an effective way of helping clinicians ensure that women do not have to undergo chemotherapy treatment that will not have any medical benefit, when their risk of cancer recurrence is in fact very low. This will mean that, where appropriate, women will be able to avoid the toxic side effects of chemotherapy.
“We’re aiming to reach a stage where all breast cancer patients receive the most appropriate treatment for them, and this research from Mitch and his team is an important step in that direction.”
In this study, scientists assessed RNA in tissue samples taken from 940 patients with ER+ breast cancer and compared the new PAM50 score, which analyses 50 genes linked with breast cancer, with the Oncotype DX test, and with a test called IHC4, developed by Breakthrough Breast Cancer. The PAM50 test uses NanoString Technologies’ nCounter equipment.
The PAM50 test provided more long-term predictive information for doctors than both the Oncotype DX test and IHC4, while being as effective as other tests in identifying women at low risk of their breast cancer recurring.
Notably, the PAM50 test categorised more patients as having a high risk of their breast cancer returning within 10 years and fewer as intermediate than the other two tests. The researchers said the PAM50 test could therefore be a more cost-effective tool while providing doctors with more relevant information for determining which breast cancer patients will benefit most from chemotherapy.
The research, published in the Journal of Clinical Oncology , was funded by Breakthrough Breast Cancer, AstraZeneca and the NIHR Biomedical Research Centre at The Royal Marsden, with additional support from Cancer Research UK.
Breast cancer is diagnosed in 50,000 women every year, with 80% of cases caused by oestrogen receptor positive (ER+) disease. Women with this type of breast cancer can be treated with hormone therapy, but for some women, the risk of their breast cancer coming back within 10 years means they are also given chemotherapy.
1. Dowsett M, et al. Comparison of PAM50 Risk of Recurrence Score
With Oncotype DX and IHC4 for Predicting Risk of Distant Recurrence
After Endocrine Therapy. JCO published online on July 1, 2013;