Growth hormone causes breast cancer, says study

A hormone that helps children grow may cause breast cancer, and women with high levels are at higher risk, a new study has found.

The hormone, IGF-1, stimulates cell division, especially during childhood, and is being investigated as an anti-ageing treatment. Its effect on the breast is unclear, but cancer results when cell division multiplies out of control.

The hormone has been linked to breast cancer before in smaller studies. For the new research, Cancer Research UK scientists at the University of Oxford analysed findings in 17 studies from 12 different countries, which together included nearly 5,000 women with breast cancer. The results showed that the 20 per cent of women with the highest blood levels of the growth factor were 28 per cent more likely to develop breast cancer than the 20 per cent with the lowest levels.

The effect was seen mainly in women with a certain type of breast cancer that responds to the female hormone oestrogen.

Professor Tim Key, lead author of the study, published in the journal Lancet Oncology, said: "Over the last few years there has been increasing interest in the possible link between growth factors and breast cancer, but the results have been inconsistent. Putting together all the information available worldwide gives us conclusive evidence that the higher a woman's blood levels of IGF-I, the higher her risk of breast cancer."

"We don't yet fully understand what affects blood levels of this growth factor, but it's possible that diet plays an important role."

Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "This hormone has received a lot of attention, not just for its role in breast cancer, but also in prostate cancer.

"Although we'll have to wait and see if particular changes to a woman's diet can affect her levels of this hormone, this study has revealed some very interesting information that adds to our knowledge about the disease."

The finding follows the discovery last week of five new genetic sites that increase a woman's risk of developing breast cancer by between 6 and 16 per cent. They take the total number of common "low-risk" genetic sites associated with breast cancer to 18.

The increased risk from each genetic site is small and scientists still don't know which genes are responsible. But as more of them are identified it may be possible to create tests for a combination of them that together significantly increase risk.

This could help doctors make decisions about prevention, diagnosis and treatment for women who are more likely to get breast cancer.

Helen George, head of science information at Cancer Research UK, said the study, published in Nature Genetics, was the largest of its kind to explore the common genetic variations that contribute to breast cancer risk.

"This research takes us a step closer to developing a powerful genetic test for the disease. Such a test could help doctors identify women who have an increased breast cancer risk so that they can make informed decisions about how to take steps to reduce their chance of developing the disease."

Life and Style
ebookNow available in paperback
ebooks
ebookPart of The Independent’s new eBook series The Great Composers
Voices
An easy-peel potato; Dave Hax has come up with an ingenious method in food preparation
voicesDave Hax's domestic tips are reminiscent of George Orwell's tea routine. The world might need revolution, but we like to sweat the small stuff, says DJ Taylor
News
i100
Arts and Entertainment
Jay Z has placed a bet on streaming being the future for music and videos
music
Arts and Entertainment
Festival-goers soak up the atmosphere at Glastonbury
music
News
Japan's population is projected to fall dramatically in the next 50 years (Wikimedia)
news
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    iJobs Job Widget
    iJobs General

    Recruitment Genius: Project Implementation Executive

    £18000 - £23000 per annum: Recruitment Genius: They work with major vehicle ma...

    Recruitment Genius: Chiropractic Assistant

    £16500 per annum: Recruitment Genius: A Chiropractic Assistant is needed in a ...

    Recruitment Genius: Digital Account Executive - Midlands

    £18000 - £26000 per annum: Recruitment Genius: They work with major vehicle ma...

    Recruitment Genius: Web Developer

    £28000 - £30000 per annum: Recruitment Genius: This company provides coaching ...

    Day In a Page

    NHS struggling to monitor the safety and efficacy of its services outsourced to private providers

    Who's monitoring the outsourced NHS services?

    A report finds that private firms are not being properly assessed for their quality of care
    Zac Goldsmith: 'I'll trigger a by-election over Heathrow'

    Zac Goldsmith: 'I'll trigger a by-election over Heathrow'

    The Tory MP said he did not want to stand again unless his party's manifesto ruled out a third runway. But he's doing so. Watch this space
    How do Greek voters feel about Syriza's backtracking on its anti-austerity pledge?

    How do Greeks feel about Syriza?

    Five voters from different backgrounds tell us what they expect from Syriza's charismatic leader Alexis Tsipras
    From Iraq to Libya and Syria: The wars that come back to haunt us

    The wars that come back to haunt us

    David Cameron should not escape blame for his role in conflicts that are still raging, argues Patrick Cockburn
    Sam Baker and Lauren Laverne: Too busy to surf? Head to The Pool

    Too busy to surf? Head to The Pool

    A new website is trying to declutter the internet to help busy women. Holly Williams meets the founders
    Heston Blumenthal to cook up a spice odyssey for British astronaut manning the International Space Station

    UK's Major Tum to blast off on a spice odyssey

    Nothing but the best for British astronaut as chef Heston Blumenthal cooks up his rations
    John Harrison's 'longitude' clock sets new record - 300 years on

    ‘Longitude’ clock sets new record - 300 years on

    Greenwich horologists celebrate as it keeps to within a second of real time over a 100-day test
    Fears in the US of being outgunned in the vital propaganda wars by Russia, China - and even Isis - have prompted a rethink on overseas broadcasters

    Let the propaganda wars begin - again

    'Accurate, objective, comprehensive': that was Voice of America's creed, but now its masters want it to promote US policy, reports Rupert Cornwell
    Why Japan's incredible long-distance runners will never win the London Marathon

    Japan's incredible long-distance runners

    Every year, Japanese long-distance runners post some of the world's fastest times – yet, come next weekend, not a single elite competitor from the country will be at the London Marathon
    Why does Tom Drury remain the greatest writer you've never heard of?

    Tom Drury: The quiet American

    His debut was considered one of the finest novels of the past 50 years, and he is every bit the equal of his contemporaries, Jonathan Franzen, Dave Eggers and David Foster Wallace
    You should judge a person by how they peel a potato

    You should judge a person by how they peel a potato

    Dave Hax's domestic tips are reminiscent of George Orwell's tea routine. The world might need revolution, but we like to sweat the small stuff, says DJ Taylor
    Beige is back: The drab car colours of the 1970s are proving popular again

    Beige to the future

    Flares and flounce are back on catwalks but a revival in ’70s car paintjobs was a stack-heeled step too far – until now
    Bill Granger recipes: Our chef's dishes highlight the delicate essence of fresh cheeses

    Bill Granger cooks with fresh cheeses

    More delicate on the palate, milder, fresh cheeses can also be kinder to the waistline
    Aston Villa vs Liverpool: 'This FA Cup run has been wonderful,' says veteran Shay Given

    Shay Given: 'This FA Cup run has been wonderful'

    The Villa keeper has been overlooked for a long time and has unhappy memories of the national stadium – but he is savouring his chance to play at Wembley
    Timeless drama of Championship race in league of its own - Michael Calvin

    Michael Calvin's Last Word

    Timeless drama of Championship race in league of its own