Having twins 'reduces cancer risks'

Mothers of twins are a third less likely to develop ovarian cancer

Women who give birth to twins may have a reduced risk of developing ovarian cancer, according to doctors.

A study carried out by the Imperial Cancer Research Fund suggests that because women who give birth to twins produce more eggs per menstrual cycle they are better protected against the disease.

Researchers reviewed either studies of 2,800 women with ovarian cancer and 7,400 without the disease.

They found that mothers of twins were around a third less likely to develop the most common forms of the tumour.

Dr Mike Murphy, head of the charity's general practise research group in Oxford, said women who give birth to twins may be protected against ovarian cancer.

Women who give birth to twins are about 30% less likely to develop the commonest forms of ovarian cancer

Dr Mike Murphy, Imperical Cancer Research Fund

"Mothers of naturally conceived, non-identical twins probably produced more eggs per menstrual cycle and we thought this should put them at greater risk of developing ovarian cancer.

"Our findings suggest that in fact, women who give birth to twins are about 30% less likely to develop the commonest forms of ovarian cancer than women who have never had twins."

Dr Murphy said that his findings contradict previous studies.

"We know that ovarian cancer is related to reproduction and ovulation and that child-bearing and oral contraceptive use reduce the risk.

"Until now scientists have thought that the risk of getting ovarian cancer might by closely related to the number of ovulations women have in their lifetime or their higher menstrual cycle hormone levels. Our findings clash with these theories."

'New insights'

An earlier study of women under 50 with breast cancer found that mothers of twins were also a third less likely to develop this form of cancer.

The group is now investigating how mothers of twins differ from mothers of single babies.

These researchers are looking at other groups of twin mothers to confirm the reduced risk of these cancers.

Dr Murphy added: "Examining the exposure of mothers of twins to hormones like gonadotrophins, oestrogen and progesterone could give us new insights into the role of hormones in ovarian cancer."

Ovarian cancer is the fourth most common cancer among women in the UK.

The study is published in the latest issue of the Journal of the National Cancer Institute in the US.