How PCOS May Increase the Risk of Endometrial Cancer

Written by Stephanie Watson
Medically Reviewed by Traci C. Johnson, MD on February 26, 2025
6 min read

Polycystic ovary syndrome (PCOS) is when your ovaries make too many hormones called androgens. Those extra hormones cause irregular periods, skipped periods, and no ovulation – which is when your ovaries release an egg each month. "Polycystic" refers to the fluid-filled sacs called cysts that form on the ovaries. 

Studies show that people with PCOS are three times more likely to get endometrial (uterine) cancer than people without this condition. That number might sound scary, but the overall risk  is low. Most women with PCOS don't get endometrial cancer, and there are things you can do to protect yourself.

Does PCOS cause cancer?

PCOS doesn't directly cause cancer. But hormone imbalances and things like obesity and diabetes that are related to PCOS might increase the risk of cancers like these: 

  • Endometrial cancer 
  • Ovarian cancer
  • Endocrine gland cancers
  • Pancreatic cancer
  • Kidney cancer

PCOS and endometrial cancer risk

If you have PCOS, the chance that you'll get endometrial cancer in your lifetime is 9%. That number is low overall, but it's still three times higher than the 3% lifetime risk in women without PCOS.

The link between PCOS and endometrial cancer is complex. Other things, like obesity and insulin resistance, may also be involved.

Anovulation means you don't ovulate and your periods don't come regularly. It's the main reason why PCOS increases the risk of endometrial cancer. 

During each ovulation cycle, levels of the hormones estrogen and progesterone in your body rise. Then levels of these hormones drop and you get your period. During each period, the lining of the uterus, called the endometrium, sheds. When you don't ovulate or get a period, estrogen levels stay high.

"When estrogen remains high without a decline, then the endometrium doesn't shed regularly and becomes thickened," explains Kristina Butler, MD, a gynecologic oncologist at Mayo Clinic in Phoenix. The extra tissue increases the risk that abnormal cells will grow in the endometrium and turn into cancer.

Insulin is the hormone that moves sugar (glucose) from your bloodstream into your cells to lower blood sugar levels. Having insulin resistance means that your cells don't respond as well to insulin. To keep your blood sugar level steady, your pancreas has to keep pumping out more and more insulin. Eventually, your pancreas can't release enough insulin to control your blood sugar level. 

Weight gain and insulin resistance are closely related. Fat tissue creates inflammation, which makes cells less sensitive to insulin. About 70% of people with obesity also have insulin resistance.

PCOS and insulin resistance

Between 50% and 70% of people with PCOS have insulin resistance. Insulin resistance, obesity, and type 2 diabetes are all closely related. Yet insulin resistance also affects women with PCOS who don't have obesity.

Obesity and endometrial cancer

Obesity is another big risk factor for endometrial cancer, whether or not you have PCOS. That's because fat cells turn other hormones called androgens into estrogen. "If your weight is elevated, the fat cells produce more estrogen," Butler says. Having more estrogen leads to more endometrial tissue and a higher risk of cancer.

"Obesity can also result in diabetes and high blood pressure, which are both risk factors for endometrial cancer," she says.

More than half of endometrial cancers diagnosed in the U.S. are thought to be related to being overweight and having obesity. Women with obesity who are diagnosed with endometrial cancer tend to have a worse outlook than those who are at a healthy weight.

Inflammation might be another reason for the link between PCOS and endometrial cancer. Studies have shown that people with PCOS have chronic inflammation in their bodies. Having constant inflammation increases the risk of several diseases, including cancer.

When you have inflammation in your body, molecules called reactive oxygen species are created to fix the damage that inflammation caused. These chemicals also damage the DNA in cells, causing changes that allow abnormal cells in the endometrium to multiply and turn into cancer. 
 

PCOS doesn't cause cancer. But without treatment, high estrogen levels and obesity related to PCOS can increase your risk of endometrial cancer and other types of cancer. Losing weight with diet and exercise helps your body use insulin better, lowers your blood sugar levels, and may help you ovulate again.

Birth control pills are the main treatment for PCOS, and they reduce the risk of endometrial cancer. The pill helps regulate your menstrual cycles and keep hormone levels steady. "Using birth control pills provides a low dose of estrogen and progesterone, keeping a balance of hormones to prevent endometrial thickening and cancer," Butler says. 

Having PCOS puts you at a higher risk of endometrial cancer. Watch for symptoms like these:

  • Bleeding from the vagina between periods or after menopause
  • Abnormal discharge from the vagina
  • Pain in your pelvis
  • A lump in your pelvis
  • Weight loss without trying

While these symptoms can be from other conditions besides cancer, have a doctor check them out. If you do have endometrial cancer, treating it early before it has a chance to spread will improve your outlook.

Many endometrial cancer risk factors are under your control. These are some ways to protect yourself:

Eat a well-balanced diet and get more active. Diet and exercise can help you get to a healthy weight. Obesity is a known risk factor for endometrial cancer. "Maintaining an appropriate weight for your height is good for cancer prevention," Butler says. Try to eat less fat overall, and especially saturated fat, which has been linked to a higher risk of this cancer. 

Take birth control pills. Pills that deliver a combination of estrogen and progestin can help bring your hormone levels back into a healthy range.

Drink coffee. Drinking four cups of coffee a day is linked to a 20% lower risk of endometrial cancer. Watch what you add to your cup, though. Pouring in a lot of cream and sugar can add to weight gain.

Get screened. See your OB/GYN or primary care doctor for human papillomavirus (HPV) tests, Pap tests, and pelvic exams. Cancer organizations have different recommendations on how often to get these tests. Ask your doctor when to get screened based on your endometrial cancer risk factors.

Treat diabetes. The diabetes drug metformin may offer some protection. Although studies have been mixed on whether this medicine prevents endometrial cancer, some evidence suggests that metformin improves survival in people with endometrial cancer and lowers the odds of the cancer coming back.

Having polycystic ovary syndrome (PCOS) increases the risk of endometrial cancer by about threefold. Endometrial cancer risk factors like obesity, inflammation, and insulin resistance are all common in people with PCOS. Taking birth control pills, losing weight with diet and exercise, and getting screened with Pap and HPV tests are ways to protect yourself from endometrial cancer if you have PCOS.

Is endometrial cancer common in PCOS?

People with PCOS have a 9% lifetime risk of getting endometrial cancer. Their risk is three times higher than that of people without PCOS. 

What is the difference between endometriosis and PCOS?

PCOS is a hormonal problem that causes missed periods and no ovulation. In endometriosis, tissue that's similar to the lining of the uterus grows in other parts of the pelvis and causes pain.

What happens to endometrium in PCOS?

A lack of ovulation in PCOS makes the uterine lining, or endometrium, get thicker and possibly turn into cancer.