So you decided not to breastfeed your baby. Whether it was a personal choice or it just didn’t work out, that’s totally okay. But did you know that not breastfeeding actually increases your risk of developing uterine cancer later on?
Not breastfeeding causes hormonal changes in your body that can raise your chances of getting cancer of the uterus. Endometrial cancer is a type of cancer that stems from the lining of the uterus (called the endometrium).
It’s the most common type of uterine cancer and the most common gynaecological cancer diagnosed in Australian women. In 2022, more than 3,300 women in Australia were diagnosed with uterine cancer. Of these cases, 90-95% were endometrial cancer.
Different risk factors, such as genes and lifestyle could be related to endometrial cancer.
In addition, research has found that not breastfeeding is associated with an increased risk of cancer incidence in women, including endometrial cancer.
What causes endometrial cancer?
According to the World Cancer Research Fund, the following factors are associated with an increased endometrial cancer risk:
- A body mass index that falls within the overweight or obese range
- High blood glucose levels
- A family history of endometrial or colorectal cancer.
There are also reproductive risk factors such as:
- Polycystic ovarian syndrome
- Maternal age at first birth
- Number of children
- Not bearing children
- Late natural menopause.
Not breastfeeding increases the risk of cancer of the uterus
Not breastfeeding causes hormonal changes in your body that can heighten your risk of uterine cancer. When you don’t breastfeed, estrogen levels may remain high. This excess of estrogen stimulates the uterine lining, raising the possibility of abnormal cell growth that leads to cancer.
Hormone related female cancers, such as breast and ovarian cancer, rely on estrogen to develop. When a woman is breastfeeding, the level of estrogen in her body is lower. This decreases her lifetime exposure to specific hormones that influence cancer risk.
While breastfeeding isn’t for everyone, knowing the potential health impacts can help you make the right choice for your situation. Your health and safety should be top priority.
For more information on breastfeeding and breast cancer risk factors, you can refer to the Australian Cancer Council’s Breastfeeding Information sheet.
For more information on how breastfeeding lowers ovarian cancer risk, you can read BellyBelly’s article Not Breastfeeding Increases Ovarian Cancer Risk.
Research on breastfeeding and endometrial cancer risk
A recent meta-analysis (a systematic review which provides the highest quality scientific evidence) analysed 8,981 women with endometrial cancer and 17,241 women in a control group.
By examining reproductive factors in relation to cancer risk researchers found that breastfeeding at any time was associated with an 11% reduction in endometrial cancer risk.
This equates to not breastfeeding increasing the risk of endometrial cancer by 12%.
Does Breastfeeding duration matter?
The longer a woman breastfeeds, the lower her risk for developing hormone related cancers, including endometrial cancer.
There is a dose-response relationship between breastfeeding and endometrial cancer risk reduction, which means that prolonged lactation has been associated with an even lower risk of endometrial cancer.
When a dose response relationship is found in research, this can make researchers more confident in claiming the results are causal rather than just an association.
This is why recommendations about breastfeeding from leading health authorities, such as the World Health Organization, exist.
Does Breastfeeding Reduce Endometrial Cancer?
Compared with women who don’t breastfeed, women who breastfeed for between 3 and 6 months reduce their risk of endometrial cancer by 7%, per child.
Breastfeeding for between 6 and 9 months reduced a woman’s endometrial cancer risk by 11 %, per child.
If a woman breastfed three children, each for 9 months, this would equate to a 33% reduced risk of endometrial cancer.
The authors concluded:
‘Our findings suggest that reducing endometrial cancer risk can be added to the list of maternal benefits associated with breastfeeding. Ongoing promotion, support and facilitation of this safe and beneficial behavior might therefore contribute to the prevention of this increasingly common cancer’.
Does not breastfeeding cause cancer?
After reading the information contained in this article, you are probably clearer about how breastfeeding reduces the risk of risk of endometrial cancer, as well as reducing the risk of breast cancer and ovarian cancer risk.
On the other hand, reading this information might leave you asking the question: Does not breastfeeding cause cancer?
To explain it simply: a risk factor is something that increases your chances of getting a disease, such as cancer. Having a higher risk factor for cancer does not necessarily mean you will get cancer; however, some people with an increased risk will get cancer.
Factors that modify risk can have different effects at different stages of life. For a postpartum woman, breastfeeding is a modifiable factor that can affect her relative risk of endometrial cancer.
Breastfeeding is an important human biological function and its importance for the health of mothers and children has been well established.
You can read more in about this in BellyBelly’s article 5 Benefits Of Breastfeeding For Baby And Mother.
Research into cancer prevention and how to lower cancer risk helps improve population health and assists people to make lifestyle choices that have a positive impact on their long term health.