Mass on Ovaries: Is It Cancer?

See what tests are used to assess the tumor

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If your healthcare provider finds a mass on your ovary, it's natural to wonder whether it's ovarian cancer. That's not always an easy question to answer.

Your healthcare provider may use many kinds of tests to figure that out, including ultrasounds, blood tests, and special calculations. They generally don't give a firm "yes" or "no" answer, but they can determine the chance that it is cancer.

In this article, you'll learn who's at risk for ovarian cancer, the various tests you may undergo, what the results mean, and what happens next.

Diagram of mass which is ovarian cancer
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Are You At Risk for Ovarian Cancer?

Anyone can develop a mass on the ovary or ovarian cancer. But certain people have a higher cancer risk than others.

Known risk factors for ovarian cancer include:

  • Being post-menopausal (no menstrual periods for more than a year)
  • Obesity
  • Family history of breast, ovarian, or colon cancer
  • Prior use of some fertility drugs or hormone replacement therapies

The Silent Killer

Ovarian cancer is sometimes called the silent killer because it often causes few symptoms until the cancer is quite advanced. Symptoms of ovarian cancer may include:

  • Bloating
  • Weight gain
  • Pain during intercourse
  • A change in bowel habits

Understanding Ovarian Cancer Symptoms, Stages, and Treatment

Tests to Assess Cancer Risk

It's difficult to say for sure whether an ovarian mass is cancerous without doing surgery. So, healthcare providers can use any of several tests to determine the risk of it being malignant.

Subjective Assessment

Subjective assessment is essentially your healthcare provider's impressions of the mass based on early tests, your symptoms, health and family history, risk factors, and other information.

While it lacks objective findings that blood markers or imaging scans can provide, this method is quite effective. Research shows subjective assessment correctly identifies ovarian cancer about 90% of the time.

It may be even more successful when combined with other methods.

Simple Rules

Also called the International Ovarian Tumor Analysis (IOTA) simple ultrasound-based rules, this test is an assessment of several characteristics of tumors.

The test looks for five features of benign masses and five features of a malignant mass as seen on an ultrasound.

The five features that indicate a benign mass are:

  • A single cavity (unilocular)
  • Solid components no larger than 7 millimeters (mm) in diameter
  • Presence of acoustic shadows (areas blocked from view of the ultrasound)
  • Smooth, multi-cavity (multilocular) tumor with the largest diameter of less than 100 mm
  • No blood flow to the mass

The five features that indicate a malignant mass are:

  • Irregular, solid tumor
  • Presence of ascites (fluid accumulation)
  • At least 4 papillary structures (distinctive clusters of cancerous cells)
  • Irregular, multilocular solid tumor with the largest diameter of 100 mm or larger
  • Very strong blood flow to the mass

If the mass only has features from the benign criteria, it's classified as benign. If it only has features matching the malignant criteria, it's classified as malignant.

If it has no features of either or a mixture of benign and malignant features, the test is considered inconclusive.

IOTA Logistic Regression Model 2

The IOTA Logistic Regression Model 2 (LR2) is used with the Simple Rules to come up with a predicted risk.

After the ultrasound, the healthcare provider considers the factors from the Simple Rules plus your age. The information is put into a calculator that comes up with a percentage that represents your risk.

However, some research suggests that the LR2 underestimates the rate of cancer.

Risk of Malignancy Index (RMI)

Many healthcare providers use the Risk of Malignancy Index (RMI) either alone or combined with subjective assessment and ultrasound findings to predict the risk of malignancy in a mass on an ovary.

The RMI is determined by three main factors:

  • U for ultrasound score: One point for each of five malignancy characteristics that are similar to those in the Simple Rules.
  • M for menopause status: One point if you're pre-menopausal, 3 points if you're post-menopausal.
  • CA-125 level: How much of a protein/tumor marker called cancer antigen 125 (CA-125) you have in your blood; a level of 35 or lower is considered normal.

Your healthcare provider then calculates the result:

  • RMI = U x M x serum CA-125 level

For example, if you had 2 ultrasound characteristics, you're post-menopausal, and your CA-125 level is 35, the formula would look like this:

  • 2 x 3 x 35 = 210

An RMI above 200 is considered suspicious. If it's over 250, you have a very high chance of cancer.

However, the keyword is “chance.” Remember that this index can help with a diagnosis, but it can't prove you do or don't have cancer.

Also, not all cancers increase your CA-125 level, leading to a low RMI in some people with cancer.

Falsely High RMI

A weakness of the RMI is that conditions like endometriosis and pelvic inflammatory disease also cause a high CA-125 level. That can inflate your RMI and overstate the odds that you have a cancerous mass.

Which Assessment Method Works Best?

The most recent studies have concluded that a combination of a subjective assessment plus Simple Rules may provide the best estimate of whether a mass on your ovaries is cancerous.

Each test has its own sensitivity and specificity, which are two ways the medical community uses to evaluate how good diagnostic tests are.

  • Sensitivity is how successful a test is in finding cancer (how often it correctly identifies the disease)
  • Specificity is how often the test correctly identifies when cancer isn't present (meaning it doesn't give you a false positive)

You can see how the tests rank against each other in the table.

Ovarian Mass Assessment Sensitivity Specificity
Subjective assessment 93% 89%
Simple Rules 93% 80%
LR2 93% 84%
Risk of Malignancy Index 75% 92%

Role of Risk Assessment Before Surgery

It's very common for a mass on your ovary to be surgically removed. You want your risk of cancer determined before the procedure.

If it's likely to be cancer, you'll probably be referred to a gynecologic oncologist (a specialist in cancers of the female reproductive system). Ovarian cancer surgery (cytoreduction surgery for ovarian cancer) is often complex and lengthy.

Studies show a specialist gives you the best chance of a successful surgery and a good survival rate, especially if they work in a cancer center that performs a lot of these surgeries.

Ovarian Cancer Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman


It's hard to tell if a mass on your ovary is cancerous. In estimating the odds that it is, your healthcare provider may look at your risk factors for ovarian cancer, symptoms, and an assessment of the mass itself.

Several proven methods are used to do this, including a subjective assessment, an ultrasound-based test called Simple Rules, or similar methods such as LR2 or RMI. Studies show a subjective assessment plus Simple Rules may be the best way.

It's important to know the chance of cancer before you have surgery to remove the mass. Having the right surgeon perform the procedure leads to better outcomes.

A Word From Verywell

Being diagnosed with a suspicious mass—or with ovarian cancer itself—can be scary and stressful. Work closely with your healthcare provider, seek support from friends and family, and consider a support group where you can learn from people in a similar position.

Take time to learn about your condition, as well. Despite modern treatments, the risk of dying from ovarian cancer is still very real. Being your own advocate in your care can help improve your outcome.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Cancer Society. Ovarian cancer risk factors.

  2. Torre LA, Trabert B, Desantis CE, et al. Ovarian cancer statistics, 2018. CA Cancer J Clin. 2018;68(4):284-296. doi:10.3322/caac.21456

  3. Meys EM, Kaijser J, Kruitwagen RF, et al. Subjective assessment versus ultrasound models to diagnose ovarian cancer: A systematic review and meta-analysis. Eur J Cancer. 2016;58:17-29. doi:10.1016/j.ejca.2016.01.007

  4. International Ovarian Tumour Analysis. IOTA simple rules and SRrisk calculator to diagnose ovarian cancer.

  5. International Ovarian Tumour Analysis. LR2 risk model to diagnose ovarian cancer.

  6. Kaijser J, Bourne T, Valentin L, et al. Improving strategies for diagnosing ovarian cancer: a summary of the International Ovarian Tumor Analysis (IOTA) studies. Ultrasound Obstet Gynecol. 2013;41(1):9-20. doi:0.1002/uog.12323

  7. National Institute for Health and Care Excellence (United Kingdom). Ovarian cancer: Recognition and initial management.

  8. Minig L, Padilla-Iserte P, Zorrero C. The relevance of gynecologic oncologists to provide high-quality of care to women with gynecological cancerFront Oncol. 2015;5:308. doi:10.3389/fonc.2015.00308

Additional Reading

By Steven Vasilev, MD
Dr. Steven Anatol Vasilev is an ovarian cancer expert double board-certified in gynecologic oncology and obstetrics/gynecology.