Giving breast cancer survivors hormone replacement therapy is safe, research shows.
For decades, doctors avoided recommending HRT to women who had overcome the disease for fear it would trigger a recurrence.
Danish scientists have now challenged concerns, sparked by two studies in the 1990s.
They found no increased risk of disease recurrence in survivors taking HRT, particularly vaginal estrogen.
This discovery gives hope to thousands of breast cancer survivors who have been tormented by the debilitating symptoms of menopause. Many have had to struggle using natural remedies or nothing at all, activists say.
But the Danish study was small and does not prove that all types of HRT are safe for breast cancer survivors.
A Danish study of 8,500 women with breast cancer has raised hopes that more women can use HRT to treat menopausal symptoms without increasing their risk of disease recurrence (stock image of a breast cancer scan)
The new research, led by Odense University Hospital, followed 8,500 postmenopausal women.
All the participants had been diagnosed with estrogen receptor positive breast cancer, which develops thanks to the female sex hormone. Around three quarters of all breast cancers in the UK are of this type.
HRT replenishes dwindling levels of estrogen, hence why cancer fears have left doctors afraid to hand out patches, gels and implants.
The drugs are currently only available by prescription.
The women in the study received tamoxifen or aromatase inhibitors. Both drugs work by stopping estrogen from working, which helps slow the growth of breast cancer.
Just over 2,000 women took some form of HRT in the years following their cancer diagnosis.
WHAT IS MENOPAUSE?
Menopause is defined as the changes a woman goes through just before and after her period stops and is no longer able to get pregnant naturally.
Some women go through this period with few or no symptoms, around 60% have symptoms leading to behavioral changes and one in four will experience severe pain.
Common symptoms include hot flashes, night sweats, vaginal dryness leading to discomfort during sex, disturbed sleep, decreased libido, memory and concentration problems, and mood swings.
Menopause occurs when your ovaries stop producing as much estrogen hormone and no longer release an egg each month.
In the UK, the average age for a woman to reach menopause is 51, according to the NHS.
Participants were followed for up to a decade, or until cancer recurrence or death occurred.
During the analysis, 1333 (16%) women had a recurrence of breast cancer.
Of these, 111 were taking vaginal estrogen, 16 another form of HRT and 1,206 were taking none.
Calculations showed that recurrence rates were 15.4% in the vaginal estrogen group and 17.1% in the other HRT group.
This compares to a 19.2% risk in the group not taking HRT.
However, researchers found a 39% increased risk of cancer recurrence in a subset of women taking both vaginal estrogen and aromatase inhibitors.
Dr Elizabeth Cathcart-Rake, breast oncologist at the prestigious Mayo Clinic in the US, said: “This large study helps inform nuanced discussions between clinicians and breast cancer survivors about the safety of vaginal therapy. to estrogens.
“The results suggest that breast cancer survivors on tamoxifen with severe genitourinary symptoms can undergo vaginal estrogen therapy without increasing their risk of breast cancer recurrence.”
“However, caution is always advised when considering vaginal estrogen for breast cancer survivors on aromatase inhibitors, or when considering menopausal hormone therapy.”
A Cancer Research UK spokesperson said further research was needed to confirm the results of the small Danish study.
Dr Channa Jayasena, a consultant reproductive endocrinologist at Imperial College London, said the results appeared credible and suggested that “future trials investigating the safety of HRT are warranted”.
However, he said: “It seems premature to recommend HRT for women after breast cancer based on this study alone.”
Professor Debasish Tripathy, an oncologist at the University of Texas, told NewScientist: “I don’t think [these results are] conclusive enough to tell someone they can safely use these estrogen products.
While the study raises hope that breast cancer survivors could use more forms of HRT, it comes as tens of thousands of women in the UK struggle to get the menopause drugs due to drug shortages. current supply.
There are around 56,000 breast cancer diagnoses in the UK, the vast majority (99%) of which are in women.
Around 11,000 people die of breast cancer each year in Britain, with three-quarters of those diagnosed with the disease surviving at least a decade.
Charity Breast Cancer Now estimates there are 600,000 breast cancer survivors in the UK.
In the United States, 260,000 cases of breast cancer are diagnosed each year, with 42,000 deaths.
The most common sign of breast cancer is a new lump on the breast. Women who notice a new lump in their breast or an area of thickened tissue should have it checked out by their GP.