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
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
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;