Most women at high risk of developing breast cancer are shunning a preventative pill, according to new research.
Wonderdrug Tamoxifen is available on the NHS to those with a family history of the disease. But six in seven have decided against taking it for a variety of reasons.
These include a fear of potential side effects, a distrust of medications in general and a belief cancer is down to fate.
The six pence a day pills have been shown to reduce the risk of breast cancer occurring by 30 per cent. They are prescribed for five years.
Study author Dr Samuel Smith, of Leeds University, said: "While it's reassuring a woman's background doesn't seem to be a barrier to taking tamoxifen, only one in seven of those at increased risk of breast cancer are taking up the option.
"Therefore it's important doctors can discuss women's concerns and provide information to help them while they are considering their options.
"Further research is needed to understand if all women eligible to take tamoxifen for prevention are getting the help and support they need."
It works by blocking the hormone oestrogen which is known to stimulate the formation of tumour cells.
Tamoxifen has been linked to hot flushes, nausea, sickness and some gynaecological symptoms which are also the main signs of the menopause.
Researchers believe many women are wrongly blaming the drug for normal age or menopause related symptoms
Around one in eight women will develop breast cancer during their lifetime and experts believe Tamoxifen can prevent many new cases.
The study, published in the journal Breast Cancer Research and Treatment, was based on a survey of 258 healthy women across England at increased risk.
They were asked whether they had agreed to take the drug to help prevent it. In-depth interviews with 16 participants identified the factors involved.
The international team - which included researchers at University College London, Queen Mary University of London and Northwestern University in Illinois - found overall those with children were most likely to take up the offer.
It is the first study of its kind since the drug was approved by medicines watchdog NICE (National Institute for Health and Care Excellence) for use in prevention.
It also suggested social class, educational attainment and ethnicity had no effect on uptake.
Cancer risk 'slashed'
Tamoxifen is most commonly given to women who have been treated for breast cancer to lower the risk of it recurring.
But prescriptions were widened following research that showed it could slash risk by around a third among women with a family history of breast or ovarian cancer.
Dr Richard Roope, senior clinical adviser and GP expert at Cancer Research UK which funded the study, said: "When an established drug like Tamoxifen is found to work not only as a treatment for breast cancer, but is also shown to reduce the risk of the disease, it seems we're making real progress.
"It's valuable to understand why women might reject tamoxifen, and this research highlights there are a range of complex reasons behind the decision.
"It's vital more work is done to understand these barriers, improve treatments and ensure doctors are getting the support they need to help women decide whether preventative medication is right for them.
"Whatever a woman's risk of developing breast cancer, keeping a healthy weight and cutting back on alcohol are also ways of reducing it."
There are no figures for the numbers of women taking the drug but almost 700,000 prescriptions were written out in 2016.
But last year a study led by Queen Mary University of London, involving almost 4,000 women, found a third stopped taking the pills early - before the recommended five year time period.
This included 12 per cent who gave up within 18 months - mostly in the belief they were suffering severe side effects.
Those who had taken dummy pills also experienced the same side effects - fuelling suspicions they had nothing to do with Tamoxifen.