A woman’s chance of developing different types of ovarian cancer could depend on whether she is sterilised or has children, research suggests. Experts already know that women with children have a lower risk of the disease, and that having more children cuts the risk significantly.
But now researchers have been able to work out the risks of different types of ovarian cancer according to whether a woman has children.
Around 7,100 women are diagnosed with ovarian cancer in the UK each year. It is the fifth most common cancer in women, after breast, lung, bowel and womb cancer.
The four most common types of ovarian cancer are serous, mucinous, endometrioid and clear-cell tumours.
Risk factors for ovarian cancer vary among the different tumour types
Experts found that women with one child had around a 20 per cent reduction in the risk of developing any type of ovarian cancer, compared to women without children.They also had around a 40 per cent reduced risk of endometrioid and clear-cell tumours.
Each other child led to an estim-ated 8 per cent reduction of risk.
Women who were sterilised also had a 20 per cent lower overall risk of ovarian cancer.
The risk was about 20 per cent lower for high-grade serous tumours – the most common type of ovarian cancer – and about 50 per cent lower for endometrioid and clear-cell tumours.
The study, presented at the National Cancer Research Institute (NCRI) cancer conference in Liverpool, involved data from more than 8,000 women with ovarian cancer.
Cancer Research UK-funded scientist Kezia Gaitskell said: “In the last few years, our understanding of ovarian cancer has been revolutionised by research showing that many cases may not in fact come from the ovaries.
“For example, many high-grade serous tumours seem to start in the fallopian tubes, while some endometrioid and clear-cell tumours may develop from endometriosis.
“We think that the significant reduction in risk among women with one child compared to women without children is likely to be related to infertility, as there are some conditions – such as endometriosis – that may make it harder for a woman to become pregnant, and which may also increase her risk of these specific types of ovarian cancer.
“For the reduced risk seen among women with tubal ligation (sterilisation), it could be that tubal ligation acts as a barrier to help prevent the abnormal cells that might cause these tumours passing through the fallopian tubes to the ovaries.
“Our results are really interesting, because they show that the associations with known risk factors for ovarian cancer, such as childbirth and fertility, vary among the different tumour types.”
Annwen Jones, chief executive of Target Ovarian Cancer, said: “This research provides a further insight into the different types of the disease, as well as where the disease begins.
“It’s important that this research paves the way for us to understand the mechanisms behind these findings, so that we can some day develop a way to lower the risk of ovarian cancer for all women. This research could also help us to develop new, more effective treatments for ovarian cancer.”