Endometriosis isn’t cancer, but the risk isn’t zero. Discover the ovarian cancer connection, symptoms to watch, and when to seek specialist evaluation. 

Introduction

If you have been diagnosed with endometriosis, you may eventually ask a worrying question: can endometriosis cause cancer? The answer is reassuring but deserves some nuance. Endometriosis itself is not cancer, and most women with endometriosis will not develop cancer. However, research has found an association between endometriosis and ovarian cancer, especially in certain forms of the disease, such as ovarian endometriomas and deep infiltrating endometriosis.

So, should you be worried? Not necessarily. The important thing is understanding the difference between having a higher relative risk and actually having a high probability of developing cancer. Those are two very different things.

Can Endometriosis Cause Cancer?

No: endometriosis is not a cancerous disease, although evidence shows an association with certain ovarian cancers and rare malignant transformation.

Is Endometriosis Cancer?

No, endometriosis is not cancer. It is a chronic gynecological condition in which tissue similar to the uterine lining grows outside the uterus. These lesions commonly affect the ovaries, pelvic peritoneum, bowel (bowel endometriosis) or bladder and can trigger inflammation, scar tissue and adhesions.

What Makes Endometriosis Different From Cancer?

One useful way to think about it is this: the endometriosis is misplaced tissue; cancer is uncontrolled malignant cell growth.

Endometriosis lesions respond to hormonal changes and can bleed and inflame surrounding tissue. Over time, this may lead to adhesions and distorted pelvic anatomy. Cancer, by comparison, is defined by malignant cellular behavior, including the ability to invade tissues and potentially metastasize.

Importantly, the severity of endometriosis does not tell you whether cancer is present. Someone can have stage 4 or deep endometriosis without having cancer.

Why Endometriosis Is Considered a Benign Condition?

Endometriosis is described as a benign disease because it does not behave like a conventional malignant tumor. Even though its lesions can infiltrate nearby structures, the condition is not classified as cancer.

The European Society of Human Reproduction and Embryology (ESHRE) recommends reassuring patients about their overall cancer risk. Its guideline states that “endometriosis is not associated with a significantly higher risk of cancer overall.”

That does not mean there is zero association with cancer. It means the overall cancer picture is more reassuring than frightening.

Can Endometriosis Turn Into Cancer?

Endometriosis does not normally progress into cancer, but rare malignant transformation can occur, with ovarian endometriosis receiving the greatest scientific attention.

What Malignant Transformation Means?

When doctors talk about malignant transformation of endometriosis, they mean that cells within or associated with an endometriotic lesion acquire changes that contribute to cancer development.

Researchers have investigated several possible mechanisms, including chronic inflammation, oxidative stress, estrogen-related signaling, genetic mutations and changes in cellular pathways. Recent reviews describe alterations involving genes and pathways such as ARID1A, PIK3CA, PTEN and PI3K/Akt/mTOR signaling in endometriosis-associated ovarian cancer.

But here is the key point: identifying biological mechanisms does not mean that an ordinary endometriosis lesion is destined to become malignant.

How Rare Cancer Arising From Endometriosis Is?

Malignant transformation is considered uncommon. Reviews of the literature often cite a transformation risk around 1% in premenopausal women, although the exact estimate varies according to the population, definition and study design.

That is why it would be misleading to tell a patient, “Your endometriosis can become cancer,” without explaining the rarity involved.

Endometriosis and Specific Ovarian Cancer Types

The strongest association is with particular types of epithelial ovarian cancer, especially clear cell carcinoma and endometrioid carcinoma. A large 2021 systematic review and meta-analysis found the association was particularly strong for these histological subtypes.

The 2024 JAMA study reached a similar conclusion, finding stronger associations between endometriosis and type I ovarian cancers, which include clear cell and endometrioid tumors.

This is one reason ovarian endometriosis receives so much attention in research.

Does Endometriosis Increase the Risk of Ovarian Cancer?

Yes, population studies show an increased relative risk of ovarian cancer, but the actual absolute increase remains much smaller than the headline percentages suggest.

What Research Shows

Research over many years has identified an association between endometriosis and ovarian cancer. A 2021 systematic review and meta-analysis involving 49 population-based studies found an ovarian cancer summary relative risk of approximately 1.93, with stronger associations for clear cell and endometrioid ovarian cancers.

More recent research has added an important layer of detail.

A large 2024 JAMA cohort study analyzed 78,893 women with endometriosis and found a 4.20-fold higher relative risk of ovarian cancer compared with women without endometriosis.

The researchers also found that risk varied substantially according to the endometriosis subtype.

Relative Risk vs. Absolute Risk

This distinction is essential when answering whether endometriosis can cause cancer.

A relative risk tells you how much more common an outcome is in one group compared with another. Absolute risk tells you how many additional cases actually occur.

The 2024 JAMA study found an adjusted risk difference of approximately 9.90 additional ovarian cancer cases per 10,000 women over a mean follow-up of 12 years among those with endometriosis.

This is why responsible patient education should include both numbers, rather than presenting the higher relative risk alone.

Why Ovarian Endometriosis and Endometriomas Matter?

An endometrioma, sometimes called a chocolate cyst, develops when endometriosis affects an ovary. Endometriomas are generally benign, but they are particularly important when discussing ovarian cancer risk.

In the JAMA study, women with deep infiltrating endometriosis and/or ovarian endometriomas had a roughly 9.66-fold higher relative risk of ovarian cancer compared with women without endometriosis. The corresponding adjusted risk difference was about 26.71 additional cases per 10,000 women over the study’s follow-up period.

Those findings do not mean an endometrioma is cancer. They mean the clinical context deserves careful assessment, particularly when an ovarian lesion has unusual features, changes over time or is accompanied by concerning findings.

What Are the Symptoms of Endometriosis?

Endometriosis can affect different pelvic organs, so symptoms vary considerably; knowing the typical pattern helps distinguish familiar disease symptoms from changes that deserve evaluation.

Common Symptoms of Endometriosis

Common symptoms of endometriosis include:

• Severe or worsening period pain
• Chronic pelvic pain
• Pain during or after sex
• Heavy or irregular menstrual bleeding
• Pain during bowel movements
• Constipation or diarrhea around menstruation
• Painful urination
• Frequent urination in some cases
• Bloating
• Fatigue
• Difficulty becoming pregnant

Dr. Lucas Minig’s clinic similarly highlights severe menstrual cramps, chronic pelvic pain, painful intimacy, heavy or irregular bleeding, bowel and bladder discomfort and fertility challenges as common manifestations.

Symptoms That Can Overlap With Ovarian Cancer

Here is where things become confusing. Endometriosis and ovarian cancer can have some overlapping symptoms, including pelvic or abdominal discomfort, bloating, changes in bowel or bladder habits and feeling full quickly.

That overlap does not mean one condition causes the other.

Persistent symptoms that are new, unexplained or significantly different from your normal endometriosis pattern should be discussed with a doctor. The American College of Obstetricians and Gynecologists notes that people with persistent ovarian-cancer symptoms may undergo pelvic examination and imaging such as transvaginal ultrasound.

Can Endometriosis Symptoms Look Like Cancer Symptoms?

Yes, some symptoms overlap, which is precisely why diagnosis should rely on clinical assessment and appropriate testing rather than symptoms alone.

Why Symptoms Alone Cannot Diagnose Cancer?

Pain, bloating or abnormal bleeding are not cancer diagnoses. They can occur with many benign gynecological conditions, including endometriosis, fibroids, ovarian cysts and hormonal disorders.

At the same time, you should not automatically blame every new symptom on your existing endometriosis.

Think of symptoms as an alarm bell, not a final verdict. An alarm tells you something needs attention; it does not tell you exactly what the problem is.

This is especially important when an ovarian mass appears on imaging or when symptoms change substantially. A specialist can consider your age, medical history, family history, endometriosis subtype, imaging findings and other risk factors before deciding what evaluation is appropriate.

How Do Doctors Evaluate Endometriosis and Possible Cancer?

Doctors usually combine symptoms, examination and imaging to understand whether findings fit endometriosis, an ovarian endometrioma, another benign lesion or something requiring further investigation.

Medical History and Pelvic Examination

Evaluation starts with the story behind the symptoms.

Your doctor may ask about:

• When your pain started
• Whether symptoms follow your menstrual cycle
• Pain during sex or bowel movements
• Bleeding changes
• Fertility history
• Previous endometriosis surgery
• Family history of ovarian or related cancers
• Previous imaging results

A pelvic examination may provide additional information, although it cannot by itself diagnose endometriosis or ovarian cancer.

Ultrasound and MRI

Transvaginal ultrasound is commonly used to examine the ovaries and pelvis and can help identify endometriomas and other abnormalities.

MRI can provide additional anatomical detail and is particularly useful when deep infiltrating endometriosis is suspected or when the extent of disease needs clarification.

Dr. Lucas Minig’s Valencia practice describes advanced imaging, including transvaginal ultrasound and high-resolution MRI, as part of evaluating endometriomas and deep infiltrating lesions.

When Surgery or Pathology May Be Needed?

Imaging can provide valuable information, but it cannot answer every question.

When a mass or lesion remains suspicious, or when surgery is clinically appropriate for severe endometriosis, the removed tissue can be examined by a pathologist. Histopathology is what establishes whether tissue is benign, atypical or malignant.

ACOG explains that when tests suggest ovarian cancer may be present, exploratory surgery may be recommended as part of evaluation.

This is one reason treatment and diagnosis should be individualized rather than based on fear-driven assumptions.

Should Women With Endometriosis Have Extra Cancer Screening?

Having endometriosis alone does not automatically mean you need additional cancer screening beyond recommended population-based guidelines, although individual risk factors can change management.

ESHRE specifically recommends that clinicians should not systematically perform cancer screening beyond existing population-based screening guidelines for women with endometriosis. Individualized screening may be considered when additional risk factors, such as a strong family history of endometriosis or relevant inherited genetic mutations, are present.

The American College of Obstetricians and Gynecologists also states that there is currently no recommended screening test for ovarian cancer in average-risk women.

So, having endometriosis does not automatically mean you need repeated CA-125 blood tests or routine scans simply to search for cancer.

When Should You See an Endometriosis Specialist?

Specialist assessment becomes particularly useful when symptoms, imaging findings or treatment decisions are complex and you need a clearer understanding of the disease and your options.

You may benefit from specialist evaluation if you have:

• Deep infiltrating endometriosis
• An ovarian endometrioma
• Recurrent endometriosis
• Bowel or bladder involvement
• Persistent pain despite treatment
• Fertility concerns
• A complex or changing ovarian mass
• Uncertainty about whether surgery is appropriate
• A need for a second opinion

The aim is not to assume cancer. It is to make sure the diagnosis and treatment plan fit the individual patient.

Endometriosis Treatment in Valencia, Spain

For women seeking specialist endometriosis care in Spain, Dr. Lucas Minig’s Valencia practice combines minimally invasive surgery, medical treatment and multidisciplinary support for complex disease.

Minimally Invasive Endometriosis Surgery

When surgery is appropriate, minimally invasive techniques can allow surgeons to treat endometriotic lesions while limiting surgical trauma.

Dr. Minig’s practice states that more than 95% of its procedures use minimally invasive techniques, including laparoscopic or robotic approaches. The treatment philosophy focuses on reducing pain, preserving fertility and improving quality of life rather than treating symptoms in isolation.

For some patients, surgery may involve removing endometriomas, excising deep lesions or treating adhesions affecting pelvic organs.

However, surgery is not automatically the right choice for everyone. Decisions should consider symptoms, fertility goals, age, disease location, ovarian reserve and previous procedures.

Personalized Care for Complex Endometriosis

Complex endometriosis often requires more than a single treatment.

Dr. Minig describes individualized plans that may combine endometriosis hormonal therapy, surgery, fertility planning, nutritional guidance and psychological support. The clinic also provides specialist consultations and second opinions for patients traveling to Valencia.

For someone worried that an endometrioma or deep endometriosis could be linked with cancer, this type of specialist assessment can help replace uncertainty with a clearer diagnosis and appropriate next steps.

Conclusion

The answer to can endometriosis cause cancer is nuanced but reassuring: endometriosis is not cancer, and most women with endometriosis will not develop cancer. Research does show an association with ovarian cancer, particularly among women with ovarian endometriomas and deep infiltrating endometriosis, but a higher relative risk should not be confused with a high absolute risk.

Rare malignant transformation can occur, especially in ovarian endometriosis, but it is not the normal progression of the disease. If symptoms change, an ovarian mass develops or imaging shows concerning features, appropriate specialist evaluation is more useful than assuming the worst.

FAQs

Can endometriosis cause cancer?

No. There is no evidence that endometriosis causes cancer overall. However, studies show a modest association between endometriosis and certain ovarian cancers, especially clear-cell and endometrioid subtypes.

Can endometriosis turn into cancer?

Rare malignant transformation can occur, particularly in ovarian endometriosis, but it is uncommon. The vast majority of women with endometriosis will not develop cancer.

Is endometriosis cancer?

No. Endometriosis is a chronic benign gynecological disease involving endometrial-like tissue outside the uterus. It may cause severe pain and complications, but it is not classified as a cancer.

Does endometriosis increase the risk of ovarian cancer?

Yes, research shows a modest increase in ovarian cancer risk. The strongest association is with clear-cell and endometrioid ovarian cancers, although the absolute risk remains low.