Breast cancer: Low-cost test could predict relapse risk
The test could identify which patients could avoid chemotherapy.
A low-cost test that measures a breast cancer patient’s response to short-term hormone therapy could help predict how likely the disease is to return, researchers believe.
The scientists say the test costs around £60 per patient, which is less than one-twentieth of the cost of the currently available genomic tests.
It looks for changes in the growth rate of cancer cells following treatment with aromatase inhibitors – drugs which stop the production of oestrogen.
The researchers say using the test could help provide reassurance for women likely to do well on standard treatment while identifying those at increased risk of relapse.
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“This important trial is the largest of its kind in the world and involved around 4,500 patients in 130 NHS breast units throughout the UK," said Professor Ian Smith, honorary professor of cancer medicine at The Institute of Cancer Research in London, who is chief investigator in the trial.
“We have shown that giving patients with early breast cancer two weeks of simple endocrine therapy using aromatase inhibitor tablets before surgery allows us to determine what is the most appropriate medical treatment after surgery for each individual patient.
“In particular, it helps us identify which patients could avoid chemotherapy with all its unpleasant toxicities. The test is much cheaper and easier than current genomic tests and we believe it should become part of the standard treatment for early breast cancer.”
A team of researchers at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust studied women with early-stage, hormone-positive breast cancer – where cancer cells grow in response to either the hormones oestrogen, or progesterone, or both.
Two-thirds of the 4,480 patients were given one of the aromatase inhibitors, letrozole or anastrozole, for two weeks before and after their surgery. The remaining women were treated with surgery and received the aromatase inhibitors at the usual time – only after surgery.
All patients were recommended to continue hormone treatment for at least five years as part of their standard care, which helps to reduce the risk of breast cancer coming back.
The researchers used the cancer growth rate test, which looks for the protein Ki67 in tumour samples, to see whether the pre-surgery hormone treatment had any effect. The test allowed the team to find out which patients were at lower and higher risk of seeing their disease come back.
“Sadly, breast cancer can return for some women, so a new way to help predict if their cancer will return means doctors could monitor these patients more closely – catching any sign of cancer as early as possible is crucial for improving survival," said Professor Arnie Purushotham, Cancer Research UK’s senior clinical adviser.
“This research could also have implications for how doctors decide to treat early-stage, hormone-positive breast cancer – potentially triaging women depending on the risk of their cancer coming back.”
Reader Q&A: How does radiation kill cancer if it causes cancer?Asked by: Odysseus Ray Lopez, US
It’s rather like the way guns can be used to commit crime, or stop it. Radiation causes cancer because its high-energy photons can cause breaks in the DNA strands in your cells. Cells can repair this damage up to a point, but sometimes the repair isn’t perfect and leaves some genes defective.
If the break affects one of the many tumour-suppressing genes in your DNA, that cell can become cancerous. But cancer cells are also more vulnerable to radiation than ordinary cells. Part of what makes them cancer cells is their ability to divide rapidly and this normally means that some of the DNA ‘spellcheck’ mechanisms are turned off.
So when a cancer cell suffers a break in a DNA strand, it’s less likely to repair it correctly. Depending where the break occurs, it might either kill the cell outright, or make it reproduce more slowly.
Radiation therapy uses a focused beam that is aimed at just the part of the body with the tumour, and the dose is carefully calculated to cause the minimum collateral damage to healthy cells. Even so, radiation therapy does very slightly increase your chances of developing a second cancer.