Menopause hormone therapy 'increases risk of breast cancer after use ends'

Henrietta Brewer
September 1, 2019

"Prior to this, a lot of doctors had a rule of thumb that up to five years of use was safe for breast cancer", said Emily Banks, co-author and professor of epidemiology at Australian National University.

Pederson said the effects of hormone replacement on breast tissue and breast cancer risk are very complex and experts are still working to completely understand them.

Risks of breast cancer may be twice what was previously thought for HRT.

Once women reach the menopause there is a dip two hormones in the body - oestrogen and progesterone - which can cause debilitating symptoms such as hot flushes, vaginal dryness and mood swings. The hormones most commonly used to treat symptoms of menopause are estrogen and progesterone.

The study also quantifies for the first time the level of risk associated with different types of menopause hormone therapy or MHT.

"The clinical relevance of the main findings lies in the magnitude of the absolute risks during and after MHT use for women who start MHT at ages 40-59 years, but the public health relevance depends additionally on the numbers of women previously and now exposed", the researchers wrote.


It has been the subject of various research studies since then but the latest findings published in the "Lancet" takes the risk of breast cancer a step further.

The new analysis used to be according to an research of information from 58 in the past revealed research on hormone substitute treatment, which integrated greater than 100,000 postmenopausal ladies with invasive breast most cancers.

At follow-up, 108,647 women (mean age [SD] 65 [7] years) developed breast cancer, of whom just over half (51%, n = 55,575) had used hormone therapy.

And the danger remains for more than a decade after the menopause treatment, a major study shows.

For current users on hormone therapy for 1-4 years, those on estrogen-progestogen preparations saw a higher relative risk versus women on estrogen-only preparations (RR 1.60, 95% CI 1.52-1.69 vs RR 1.17, 95% CI 1.10-1.26).

They have estimated that the treatment, also known as hormone replacement therapy (HRT), may have already caused around one million breast cancers in western countries - one-twentieth of the total since 1990. If a woman had used MHT for less than a year, there was little excess risk thereafter.


Although the study did not prove HRT causes the disease, the researchers suggested guidelines should be reviewed in light of the compelling new evidence. At these ages, breast cancer is the most common malignancy in western nations; almost 3% of ladies are determined to have it during their 50s.

"As always, before starting any treatment a discussion between doctor and patient of available treatment options as well as their risks and benefits should be undertaken", he said.

In general, the US Food and Drug Administration says not to take hormone therapy if you have problems with vaginal bleeding; have or had a history of certain cancers; have or had a blood clot, stroke or heart attack; or have a bleeding disorder, liver disease or allergic reactions to hormone medicine. She wasn't involved in the new report.

"These findings should not put women off taking HRT if the benefits - such as protection of bones and decrease in cardiovascular risk - outweigh the risks", she said.

In Western countries, the incidence of breast cancer among women of average weight who have never used menopausal hormone treatments is about 6.3 per 100 women.

The topical use of vaginal oestrogens, applied as a cream, is also relatively risk-free, she added.


He said: "We would urge patients not to panic as a result of this research, and to continue taking HRT as it has been prescribed to them -- and we would urge prescribers to do so as normal until clinical guidelines recommend otherwise".

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