Why are we seeing increasing rates of endometrial cancer?

Unlike most other types of cancer, endometrial cancer rates have been increasing in Australia with more women being diagnosed every year.

Endometrial cancer is cancer of the endometrium, which is the inner lining of the womb. Cancer Australia reports in 2018, there were 2,643 new cases of endometrial cancer diagnosed in Australia, and in 2022 this number has risen to over 3,000. Unfortunately, it is projected that endometrial cancer diagnoses will continue to rise considerably in the next decade.

Survival rates for less aggressive forms of endometrial cancer are quite high overall. The chance of such a woman surviving for at least five years after her cancer diagnosis is 83%. However, there are different subtypes of endometrial cancer, with some types much more aggressive with poorer survival rates. Along with the increasing incidence, we are seeing increased mortality rates in the aggressive subtypes.

Why are we seeing increases in endometrial cancer rates?

Illustration of the human body and the reproductive system

The increasing numbers have been largely attributed to increasing obesity rates and an aging population. Endometrial cancer is most common in women aged 60-80 years.

Over half of endometrial cancers are attributable to obesity, which means a body mass index of 30 kg/m2 or higher. Endometrial cancer is linked to obesity as obese people tend to have chronic inflammation and higher blood levels of oestrogen. Higher degrees of body inflammation changes how the body manages hormones such as insulin and oestrogen. Insulin is a hormone that regulates sugar in the body, and oestrogen is the sex hormone responsible for the development and regulation of the female reproductive system. It is thought that too much insulin and estrogen hormones may cause cells to divide and reproduce uncontrollably, and could result in tumours that are cancerous.

Endometrioid (type 1) is the subtype of endometrial cancer that is predominantly linked to obesity, rather than type 2 (non-endometrioid such as serous) where there is no link to obesity. Over 80% of uterine cancers are type 1 which is the subtype with the highest survival rates. Type 2 accounts for the remaining 15 to 20% of cases, and behave more aggressively, respond less to treatments, all of which is resulting in poorer survival outcomes.

Experts also hypothesise the increasing rates are attributed to increases in other risk factors such as shifts in reproductive trends, by having fewer children and delaying childbirth until later in life. Lifestyle factors can also increase risk, including high blood pressure and diabetes. We are seeing more people diagnosed with these diseases.

Hormone replacement therapy (HRT) can also affect endometrial cancer risk. Using estrogen-only HRT increases endometrial cancer risk, however combination progesterone-estrogen HRT reduces the risk of estrogen-induced endometrial cancer, depending on length of use.

More common among different racial groups

Researchers in the US are also finding that women of colour had more than twice the rate of deaths from uterine cancer overall, and of the more aggressive type, when compared to other racial and ethnic groups. The study found annual rates increased 3.4% among Asian women, 3.5% among Black women, 6.7% among Hispanic women, and 1.5% among white women. The reasons for these trends are not well understood yet and continue to be researched. More research is needed to understand the development of endometrial cancer.

Early detection

To improve the prognosis it’s important to be aware of the signs and symptoms to catch the disease at an early stage.

In particular, it is important for premenopausal women who experience unusual and abnormal bleeding to be checked. A Pipelle endometrial sampling is ideally done during such a bleeding episode and takes a small cell sample from the inner lining of the uterus.

Menopausal women who experience any bleeding should see a doctor. An ultrasound will check the thickness of the endometrial lining, which should not be higher than 3 or 4 mm in menopausal women. While not all patients with bleeding have endometrial cancer, abnormal bleeding is the most common sign of endometrial cancer.

If endometrial cancer is diagnosed or if your patient is concerned about the possibility of endometrial cancer, the patient should be seen by a gynaecologist or a gynaecological oncologist sooner rather than later.

If you are concerned about any of these symptoms and wish to discuss them with a Gynaecological Oncologist, Enquire about an appointment

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