Statins could be prescribed to breast cancer survivors after researchers discovered the cholesterol-lowering drugs may prevent the disease from returning.
Scientists have known for years that the hormone oestrogen fuels cancer and causes it to spread.
Up to 80% of breast cancer cases are 'ER-positive', meaning that they have more oestrogen receptors (ER) than normal breast cells and are particularly sensitive to oestrogen. It is estimated that up to 40,000 women are diagnosed with ER-positive breast cancer each year.
But in some cases, patients do not respond effectively to standard hormone-blocking therapy, which is designed to target oestrogen production.
But in a new study, researchers discovered that certain types of breast cancer use cholesterol to produce a molecule, called 25-HC, which is having the same impact as oestrogen and may explain the cancer's resistance to therapy.
For these patients, taking statins to lower cholesterol was found to halve their chance of the disease returning in 10 years.
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“During the course of treatment, ER-positive breast cancers, that are ‘fed’ by oestrogen, often become resistant to standard hormone therapy. Our research has demonstrated that these cancer cells can use a cholesterol molecule to mimic oestrogen so that they continue to grow without it," lead researcher Dr Lesley-Ann Martin explained.
"This is hugely significant. Testing the patient’s tumour for 25-HC or the enzymes that make it may allow us to predict which patients are likely to develop resistance hormone therapy, and tailor their treatment accordingly.
"Our study also demonstrates that statins could be a valuable addition to breast cancer treatment, and that this warrants investigation in clinical trials."
According to the researchers, cholesterol is an important molecule that allows the body to build and maintain cell membranes and produce a number of hormones.
As well as obtaining cholesterol from food, the body produces its own cholesterol in a process called the cholesterol biosynthesis pathway.
Using breast cancer cells grown in the lab, a team of scientists led by Dr Martin investigated the processes that cause women with ER-positive breast cancer to relapse while taking aromatase inhibitors (AIs), generally taken for five years after surgery.
The researchers grew ER-positive cells in the absence of oestrogen, mimicking the cells found in tumours being treated with AIs.
They found that the cholesterol biosynthesis pathway was enabling the cells to make their own fuel by producing 25-HC, allowing them to continue growing despite a lack of oestrogen.
Using these models, the team found that blocking the production of parts of this cholesterol-production mechanism slowed down the proliferation of the cancer cells by 30-50%.
Baroness Delyth Morgan, chief executive at Breast Cancer Now, said this is a "really crucial discovery".
"Far too many women have to deal with the potentially devastating consequences of their breast cancer coming back and this research presents an important opportunity to improve the effectiveness of today’s most commonly used treatments," she added.
"This study breaks new ground in uncovering how some breast cancers continue to survive without oestrogen and suggests that women could benefit from adding statins to standard anti-hormone treatments.
“But this is early research and greater clinical evidence is now needed to understand the potential risks and benefits of this approach."
The research was completed by scientists working with the Breast Cancer Now Toby Robins Research Centre at The Institute of Cancer Research and is published in full in the journal Breast Cancer Research.
Breast Cancer Signs And Treatment
What Are The Symptoms?(01 of10)
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"A new painless, firm breast lump with irregular margins is a potential symptom of breast cancer," says Dr. Sandhya Pruthi, a breast cancer researcher at the Mayo Clinic. "The cancer diagnosis is confirmed following a biopsy of the lump." She notes that usually, women who are newly diagnosed with breast cancer are healthy and don't feel sick at all. (credit:LarsZahnerPhotography via Getty Images)
Other Symptoms(02 of10)
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Another potential symptom/sign of breast cancer, Pruthi notes, is a new onset of persistent redness on the skin overtop the breast with an orange peel appearance. This would also need a biopsy to confirm a diagnosis of breast cancer. (credit:Image Source via Getty Images)
Metastatic Cancer Symptoms(03 of10)
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"If the cancer is very advanced (metastatic) then the symptoms may also include weight loss, bone pain, headaches, nausea and persistent cough," Pruthi says. (credit:pamela burley via Getty Images)
What Are The Risk Factors?(04 of10)
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Some commonly associated risk factors, Pruthi says, are menstruation before age 11, menstruation after age 54, a first pregnancy after age 35 and a family history of relatives diagnosed with breast or ovarian cancer. (credit:AP Photo/M. Spencer Green)
Are There Any Lifestyle Risk Factors?(05 of10)
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"There is evidence in the literature that obesity after menopause, lack of regular exercise, consuming greater than more or more alcoholic beverages daily, and a high fat diet can all be associated with a higher breast cancer risk," Pruthi notes. But, she points out, "women need to know that any woman can get breast cancer even in the absence of any of these risk factors." (credit:Adrian Samson via Getty Images)
Can I Eat Anything To Prevent It?(06 of10)
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There are no specific types of diets, Pruthi says, but rather women are encouraged to eat fruits, vegetables, fibre, and minimize their alcohol and fat intake, as well as get regular exercise. (credit:lola1960 via Getty Images)
How Do Doctors Determine Treatment?(07 of10)
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"The most current treatment of breast cancer has taken on a individualized approach and is dependent on the biology or aggressive features of the breast cancer," Pruthi explains. "Breast cancer is a heterogeneous disease and this means that are many sub-types and different degrees of aggressiveness. So staging, which typically takes into account common prognostic features such as tumour size and if lymph nodes are involved, are no longer the only factors doctors use to determine treatment options." (credit:Christopher Futcher via Getty Images)
So What Do They Look At?(08 of10)
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"Today the biology of the tumour is also characterized by molecular markers (also known as predictive markers) such as if the estrogen or progesterone receptor is positive or negative and if the HER 2 protein is positive or negative," she says. "This helps decide who will benefit from a specific chemotherapy regimen, hormonal medications known as antiestrogens or who may need both chemotherapy and hormonal treatment." (credit:BluePlanetEarth via Getty Images)
What About Preventative Mastectomies?(09 of10)
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"Preventive mastectomy is an option for women at very high risk for developing breast cancer because they are BRCA 1 or 2 gene positive or if someone has hereditary predisposition to getting breast cancer but chooses not to have the genetic testing done," Pruthi says. "It is prudent that women who are considering this surgery know their family history in detail. Based on the moderate or strong family history, your doctor would recommend you meet with a genetic counselor to go over the family pedigree and help decide who should test for the breast cancer gene, when to test and how to interpret the genetic test results before proceeding with this preventive surgery." (credit:Jesús Jaime Mota via Getty Images)
Are Other Preventative Treatments Available?(10 of10)
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"High risk women who have had precancerous breast biopsies or strong family history may also be eligible to take preventive medications such as tamoxifen, raloxifene or exemestane to reduce breast cancer risk," Pruthi adds. (credit:art-4-art via Getty Images)