Bacteria revealed at smear test could identify women at high risk of ovarian cancer, study says

Women may be at higher risk of ovarian cancer if they have fewer protective bacteria in the vagina, according to new research which suggests a simple smear test could help treat the disease earlier.

Smear test samples from women with ovarian cancer, as well as women with a genetic risk of the disease, had significantly lower levels of lactobacilli bacteria than healthy women of the same age, researchers led by University College London (UCL) said.

If backed up by further studies this could be used to inform treatment decisions for women at risk ovarian cancer, which could let them safely delay surgery to remove their ovaries, a procedure that would prevent them conceiving naturally.

Hayley Minn was 23 when she found ou she had a mutation in the BRCA1 gene which means she is at increased risk of developing breast cancer, and had a preventative mastectomy at 27.

The mutation also means her chances of developing ovarian cancer are between 40 and 60 per cent, compared to 2 per cent of the general population.

“I've been told I should seriously start thinking about having a hysterectomy when I'm 35, which is extremely scary as I do want children," Ms Minn said.

“So anything that buys me more time and reassures me that ovarian cancer isn’t developing, is a game-changer for me.”

Ovarian cancer, kills more than 4,000 women in the UK each year. But it can be difficult to detect at an early stage where treatment will be most effective, because symptoms are often non-specific symptom, such as bloating and fatigue.

The new study, published in the journal Lancet Oncology, analysed samples from cervical screening swabs on 580 women aged 18-87 from the UK, Czech Republic, Germany, Italy and Norway.

Some had recently received a diagnosis, others carried the BRCA1 gene and 295 were not at high risk.

Young women carrying the gene had three times fewer lactobacilli on average than those without the gene, while those with a close family member with ovarian cancer also had lower levels.

Among BRCA1 carriers under the age of 30, a quarter had “low” lactobacilli levels, something that wasn’t seen at all in women in their teens and twenties without the mutation.

"This is a novel approach and could revolutionise the way that we can intervene and change the implications of being at high risk of ovarian cancer development,” Prof Martin Widschwendter, head of the department of Women's Cancer at UCL.

"It's the first time that we have been able to demonstrate that women with gene mutations have a change in their vaginal microbiome."

In other parts of the body, like the gut, Lactobacilli help prevent “unfriendly” bacteria taking over and causing issues.

Identifying an imbalance in the microbial ecosystem in the vagina could be a sign that there are issues elsewhere in the reproductive tract, such as the fallopian tubes where most ovarian cancers start.

Changes in bacteria levels can cause inflammation, where the immune system increases activity against a potential threat, and it could be that this is a factor increasing cancer risk and potentially treating ti could reduce this risk.

However the study cannot rule out that abnormal vaginal bacteria could be a symptom of something else which also raises cancer risk.

Athena Lamnisos, CEO of the Eve Appeal, a gynaecological cancer research charity, said women at risk of ovarian cancer face a “stark choice” which could see them “plunged into early menopause”.

"This research is an exciting step forward in both understanding the factors that potentially impact on cancer development but also, and most importantly, in developing interventions that can reduce that risk,” she added.

"If that can be done by something as simple as adjusting the vaginal microbiome - that is a game-changer."