Endometriosis may affect cancer risk, regardless of having given birth
Doctors researching a possible link between endometriosis and cancer have shown that any increased risk is not affected by whether or not a woman has given birth.
Endometriosis is a condition in which the lining of the womb grows outside the uterus, and is a common cause of infertility.
Dr Joanna Owens, Cancer Research UK's senior science information officer, commented: "Previously published research suggests that endometriosis can affect cancer risk, but further studies are needed to fully explain this link."
Researchers at the Karolinska University Hospital in Stockholm, Sweden, studied data from 63,630 women who had been diagnosed with endometriosis between 1969 and 2002.
Their results suggested that women with endometriosis were slightly more likely to develop ovarian cancer, kidney, endocrine, and thyroid cancers.
However, there was no significant difference in risk between women who had never given birth and those who had children, despite previous studies suggesting that women with no children may be more at risk from certain cancers.
Speaking at the 23rd annual meeting of the European Society of Human Reproduction and Embryology, Dr Anna-Sofia Melin, a specialist in the hospital's department of obstetrics and gynaecology, commented: "Several studies have shown an increased cancer risk among women with endometriosis, especially ovarian cancer.
"Infertility and never having given birth are also known risk factors for different types of cancer, such as breast and endometrial cancer."
However, she said that the study had shown that endometriosis and never having given birth "did not combine to give a higher risk of cancer", and in fact the researchers found that women with endometriosis had a 29 per cent reduced risk of cervical cancer.
Dr Melin added that future studies will hopefully lead to better care for patients and to an early diagnosis if cancer should occur.
Cancer Research UK's Dr Owens added: "Our advice to all women is to know your body, contact your doctor promptly if you notice any changes, and attend screening when invited."