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Endometriosis vs. Endometrial Cancer: Key Differences You Should Know

A midwife and gynecologic oncologist debunk the misconception that the two similarly named conditions are linked, discussing their causes, symptoms, and more.

Endometriosis and endometrial cancer are two common gynecologic conditions that affect women and those born female. Even though their names sound similar, they are not linked, meaning one will not increase your risk for the other. However, symptoms can overlap, making it confusing to tell which is which.  

To help understand the differences between endometriosis and endometrial cancer – also known as uterine cancer – what causes them, how they’re found and how to reduce overall risk, we spoke with midwife Ellen Appleton, CNM, and gynecologic oncologist Lindsey Ford, MD.  

What is the endometrium?  

Endo derives from Greek origins, meaning “inner” or “inside.” The endometrium is the internal lining of the uterus, explains Appleton, which thickens during the menstrual cycle to prepare for a fertilized egg. The primary purpose of the endometrium is to support a pregnancy, notes Dr. Ford.  

A Difference in Disease Processes 

Both endometriosis and endometrial cancer involve endometrial tissue, are influenced by estrogen, and should be addressed with your OBGYN providers, says Appleton. Naturally, cancer, when left untreated, can become fatal. Endometriosis can’t.  

Endometriosis is a benign, or non-cancerous, disease, explains Dr. Ford. “It does not act with the same uncontrolled growth and capability to damage cells that cancer does.”  

What Causes Endometriosis?  

Endometriosis impacts 6-10% of women pre-menopause; most are diagnosed in their 30s and 40s. The exact cause of endometriosis is unknown, explains Appleton, but the most agreed-upon theories are that reverse (or retrograde) menstruation (in which blood flows back up through the fallopian tubes) and excess endometrial tissue (also known as implants) play a role.  

You may be more at risk for endometriosis if you:  

  • Have a family history of the disease 
  • Have short menstrual cycles  
  • Started your first period young  
  • Had children later in life 
  • Have heavy bleeding 
  • Have any defects in the reproductive organs, or any other complication which makes you bleed heavily.  

“Endometrial implants often spread to the ovaries and fallopian tubes, as they are the most vulnerable,” explains Appleton. “In rare cases, however, they can grow further out, reaching the abdominal cavity, bladder, intestines and so on. Implants can cause inflammation, scar tissue and adhesions, which can stick and pull organs closer together, like a spider web.”  

What Causes Endometrial Cancer?  

Endometrial cancer is the most common gynecological cancer, and it’s becoming increasingly more prevalent, notes Dr. Ford. According to the American Cancer Society, it’s estimated that there will be more than 65,000 new cases diagnosed in 2022 

You may be more at risk for endometrial cancer if you:  

  • Have never been pregnant  
  • Have hormonal imbalances/increased estrogen due to estrogen supplementation or conditions such as PCOS/polycystic ovarian syndrome  
  • Take hormone therapy for breast cancer  
  • Have an inherited cancer syndrome, such as Lynch Syndrome  
  • Are overweight or obese  
  • Are of African American descent  

“Most endometrial cancers are diagnosed post-menopause; however, more people are being diagnosed younger than age 50 due to weight and unhealthy lifestyle factors,” added Dr. Ford. “It’s estimated that 70% of cancers are attributed to obesity. Fat cells have the power to convert testosterone to estrogen, so that’s how we end up with a cancer-causing excess in estrogen.”

[Editor’s Note: Read more about how weight can impact cancer risk and sustainable ways to achieve healthy weight loss.] 

How Do We Determine Which is Which?  

Symptoms: Endometriosis is associated with chronic pain and severe pelvic cramping during menstruation, sex and even while urinating. “Often, this pain is so intense that it can’t be relieved with over-the-counter pain relievers,” Appleton adds.  

While endometrial cancer can sometimes present with this kind of pain, the most common warning signs for those who are pre-menopausal are spotting between periods; heavy periods; or any other changes to the menstrual cycle, explains Dr. Ford. For those who are post-menopausal, any vaginal bleeding is a ‘red flag.’   

Diagnoses: Endometriosis can only truly be diagnosed with surgery, says Appleton, but surgery isn’t always necessary. “A biopsy is needed to confirm whether or not it’s an endometrial implant. However, depending on someone’s health status and preferences, a more conservative approach can be taken, excluding any other underlying cause of the pain, and treating it based on symptoms” 

Endometrial cancer, unlike other cancers, isn’t routinely screened for, continues Dr. Ford. “This is why it’s so important to mention any changes you experience either pre- or post-menopause. There are many other causes for these symptoms, but we have to consider – and hopefully, rule out – cancer.”  

Endometrial cancer can be diagnosed with a biopsy of the endometrium. A thickened endometrium is common, and may be seen during a pelvic ultrasound, but doesn’t necessarily mean cancer, adds Dr. Ford.  

What You Can Do  

Reduce Your Risk: The best thing you can do is lead a healthy lifestyle, suggests Appleton. Exercise three to five times a week and follow a well-balanced diet to maintain a healthy weight (a modifiable risk factor).  

“Endometrial cancer, more so than other cancers, is closely linked to obesity,” explains Dr. Ford. “Studies show that each time BMI (body-mass index) increases by 5 units, the risk for endometrial cancer increases by 50%.”  

Treatments: If you are diagnosed with endometriosis, you may be prescribed contraceptives to decrease your estrogen levels or gonadotropin-releasing hormone (GnRH), which induces a menopause-like state. An IUD may also be effective, as well as surgical removal of lesions. In serious cases, a hysterectomy (removal of the uterus and cervix) and oophorectomy (removal of both ovaries) may be performed.  

If you are diagnosed with endometrial cancer, a hysterectomy will typically be curative. In more advanced cases, radiation and/or chemotherapy may be needed.  

Appleton and Dr. Ford encourage patients to always advocate for their health. “If you have a biopsy or another test that comes back negative, and you’re still suffering, continue to communicate that — follow up or seek a second opinion,” said Dr. Ford.  

“When pain starts to impact peoples’ daily lives, it’s not okay. It’s not just a ‘bad period,’ it’s relentless back pain, bleeding after sex, painful bowel movements and more, which can trigger mental health issues as well,” says Appleton. “As providers, we really need to understand and draw a ‘line’ between normal pain and abnormal pain.”

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