A QIMR Berghofer study has revealed some important new findings about the role of pregnancy and miscarriage in reducing endometrial cancer. These insights are helping researchers to better understand what drives endometrial cancer and provide hope for future prevention.
Endometrial cancer arises from the lining of the uterus, called the endometrium. It is the most common type of cancer of the uterus and the most common gynaecological cancer diagnosed in Australian women each year.
It is well known that having a full-term pregnancy reduces a woman’s risk of developing endometrial cancer, however a new study led by world-leading epidemiologist QIMR Berghofer Professor Penny Webb, has found the risk continues to drop with each additional pregnancy – a surprising new finding.
‘Our research has shown that not only does each additional full-term pregnancy reduce risk by about 15 per cent, the reduction continues for up to at least 8 pregnancies,’ Professor Webb said.
The researchers examined pregnancy data from 30 studies conducted around the world, including Australia, and also discovered miscarriages in pregnancy reduce risk of endometrial cancer.
The facts of endometrial cancer
In 2016, uterine cancer was the fifth most commonly diagnosed cancer in Australia among females. It is estimated to remain the fifth most commonly diagnosed cancer among females in 2020.
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‘We have clearly shown for the first time that pregnancies that end in a miscarriage also reduce risk of endometrial cancer by about 7 per cent,’ Professor Webb said.
This important finding raises questions about the commonly held belief that hormone levels in the last trimester provide the protective effect against endometrial cancer.
Associate Professor Susan Jordan, who was the lead author of the QIMR Berghofer study and is now at the University of Queensland School of Public Health, said more research is needed to identify other factors that underlie this protective effect.
‘Our analysis in this large group of women shows that while a full-term pregnancy is associated with the greatest reduction in risk for endometrial cancer, even pregnancies that end in the first or second trimester appear to provide women with some protection,’ Associate Professor Jordan said.
This suggests that very high progesterone levels in the last trimester of pregnancy are not the sole explanation for the protective effect of pregnancy. If women who experience miscarriage have a 7 to 9 per cent reduced risk of endometrial cancer then early pregnancy factors may also be playing a protective role against this disease.’
Researchers also examined the risk factors of gender, and found women who had only boys or a mix of boys and girls had a lower risk of endometrial cancer compared to mothers of only girls. There was also no extra benefit from twin or multiple births.
While more research is needed, these important findings provide vital clues that will help researchers understand more about endometrial cancer, which according to Cancer Australia, affected over 3,000 women in 2019 and sadly claimed the lives of 350 women in 2018.
‘Unlike many other cancers, endometrial cancer rates are increasing so it is vital that we get a better understanding of the factors that affect a woman’s risk,’ Professor Webb said.
‘If scientists can understand what drives endometrial cancer, there’s hope that we may be able to prevent women from developing it in the future.’
The facts of endometrial cancer
In 2016, uterine cancer was the fifth most commonly diagnosed cancer in Australia among females. It is estimated to remain the fifth most commonly diagnosed cancer among females in 2020. |
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