How Ovarian Cancer Is Diagnosed

ovarian cancer diagnosis
© Verywell, 2018

There a number of tests and procedures that may be used to diagnose ovarian cancer, including a pelvic exam; imaging tests, such as transvaginal ultrasound, CT, MRI, or PET scan; and blood tests, such as CA-125. In order to make a diagnosis, a biopsy is usually needed to both confirm that a mass is malignant (cancerous) and to identify the type and subtype of the disease. When a diagnosis is made, these results and further tests are used to determine the stage of the disease, which will help determine the best course of treatment.

Self Checks/At-Home Testing

Unfortunately, there are no self-checks for ovarian cancer. Furthermore, at-home genetic tests cannot definitely determine your risk of developing the disease. It's important for all women to be familiar with the signs and symptoms and to talk to their doctors if they have any risk factors for the disease.

Physical Exam

There are no screening guidelines for ovarian cancer. However, a routine pelvic exam performed by your physician (or one conducted because of the presence of symptoms) may detect a mass in the region of your ovary, referred to as an adnexal mass. However, this check has limitations.

The exam is performed bimanually with one hand in your vagina and one on your abdomen. Since the doctor is feeling for your ovary beneath fatty tissue, the exam is less accurate in identifying a mass in people who are overweight or obese. Even in thin women, a pelvic exam can easily miss small ovarian tumors.

It's important to note that a Pap smear alone (without a bimanual exam), while helpful in detecting cervical cancer, is not very helpful in finding ovarian cancer.

Imaging

Imaging tests are needed both the find small ovarian masses and to further understand masses that can be felt on exam. Options include:

Transvaginal Ultrasound

A pelvic ultrasound is a test that uses sound waves to create a picture of the pelvic organs. It is usually the first test performed to evaluate an ovarian mass and does not expose people to radiation. The procedure can be done either abdominally (the probe is positioned on top of your skin) or transvaginally (the probe is inserted into the vagina to get closer to the ovary). However, the former is not as good as the latter at defining ovarian masses, especially those that are small.

An ultrasound can give an estimate of the size of the mass, as well as determine if it is a simple cyst, a complex cyst, or solid. Simple cysts are usually benign. A complex cyst may be benign, but raises concern about being cancerous if it contains nodules or excrescences (abnormal growths). An ultrasound can also look for free fluid in the pelvis, something that is often seen with more advanced tumors.

Abdominal and/or Pelvic CT Scan

A CT scan uses a series of X-rays to create a picture of the abdomen or pelvis. It may be used to aid in diagnosis, but is more often used in staging cancer. It is a good test to evaluate lymph nodes, the intestine, the liver, and the lungs (chest CT scan) for any evidence that cancer has spread (metastasized).

Terms you may see on your report include ascites (fluid build-up in the abdomen); metastases (areas of spread); carcinomatosis (widespread areas of tumor); omental cake (thickening of the omentum, the fatty layer that lies over the abdominal organs); fat stranding (swelling in abdominal fatty tissues); and effusion (fluid build up). Also, lymph nodes may be described as enlarged. Enlarged lymph nodes are usually larger than 2 cm (around 1 inch) in diameter and may have areas of central necrosis (cell death) if cancer is present.

MRI

An MRI (magnetic resonance imaging) may be used in a way similar to a CT scan but does not involve radiation, making it a safer test during pregnancy. MRI tends to be better than CT at defining soft tissue abnormalities and may be used to clarify findings on other tests.

PET Scan

While CT, MRI, and ultrasound are structural imaging tests (they look for physical abnormalities), a PET scan is a functional test, which is a measure of activity. This sensitive test looks for evidence of metastases (spread) anywhere in the body and is helpful in discriminating between scar tissue and cancer.

With a PET scan, a small amount of radioactive sugar is injected into the bloodstream. The scan is done after the sugar has had time to be absorbed by cells. More actively growing cells, such as cancer cells, will light up on this imaging, which is usually combined with CT. 

Labs and Tests

In addition to imaging studies and an exam, blood work is done to look for evidence that an abnormality found on the exam and/or imaging is cancerous or not. Tests may include:

Blood Work for Tumor Marker Detection

Certain blood tests can detect proteins known as tumor markers. Some of them are produced by both normal and cancerous ovarian cells, so ovarian cancer is indicated if amounts present in the blood are higher than normal.

Identifying these tumor markers in a blood sample is not an effective way to screen for ovarian cancer, but it can be helpful in making the diagnosis and following the response of these cancers to treatment. 

  • CA-125: CA-125 is a test commonly performed when there is concern about a possible ovarian cancer. While the level is elevated in a large percent of epithelial ovarian tumors, there are many reasons why the level may not be elevated (false negatives) and many reasons why it could be high without an ovarian cancer present (false positives). A few of the other conditions that can increase CA-125 include pregnancy, polycystic ovarian syndrome, pelvic inflammatory disease, pancreatitis, cirrhosis, and lupus.
    • With ovarian cancer, CA-125 is more likely to be elevated in serous and endometrioid subtypes. While there are many potential causes of a false positive result, a very high result (such as a CA-125 over 1000) increases the chance that ovarian cancer is the culprit. The level of CA-125 at the time of diagnosis may also help predict the prognosis.
  • Human epididymis protein 4 (HE4): HE4 may be helpful when combined with CA-125 and is most likely to be elevated with serous and endometrioid epithelial ovarian cancers. This test is less helpful in younger women, due to the type of ovarian cancers often found in premenopausal women.
  • CA 72-4: CA 72-4 may be elevated in several other (usually digestive tract) conditions and the level at the time of diagnosis may help predict prognosis for some people.
  • CA-19-9: This tumor marker is more common in mucinous epithelial ovarian tumors.
  • CEA (carcinoembryonic antigen): CEA is a non-specific marker and can be elevated in a number of other cancers, as well as gastrointestinal conditions.
  • Alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG): People are most familiar with HCG being the source of a positive pregnancy test, and AFP being tested during pregnancy, but both of these markers can be elevated in germ cell tumors.
  • Estradiol and inhibin: Both estradiol and inhibin are more likely to be elevated in girls or women with sex cord-stromal tumors or germ cell tumors, with inhibin often secreted by granulosa cell tumors in young women (a type of stromal tumor).

Other Blood Tests

Other blood tests that may help in making a diagnosis include a complete blood count (CBC), LDH, alkaline phosphatase, and a sed rate or C-reactive protein test (which looks for inflammation).

Research found that a combination of one of the red blood cell indices, known as red blood cell distribution width (RDW), and mean platelet volume (MPV) may be helpful in predicting which ovarian tumors are cancerous and which are not. (RDW tends to be high and MPV low with ovarian cancer.) 

Ovarian Risk Index

A number of different risk of malignancy indices look at a combination of findings on tests and imaging to predict whether a problem could be ovarian cancer and if a biopsy is needed. While these may be helpful, the objective measures of estimating risk are more accurate when used along with the subjective assessment of an expert, such a gynecological oncologist. 

Surgical Biopsy

A biopsy of a suspicious lesion is usually done via surgery. At times, a needle biopsy (in which a needle is inserted through the skin) may be considered, but it's thought that if ovarian cancer is present, this could result in what's known as seeding (the spread of the tumor).

A surgical biopsy can be done either with a laparoscopy, a surgery in which a few small incisions are made in the abdomen and a probe with a camera and instruments are inserted, or a laparotomy, where a traditional incision is made in the abdomen. A biopsy (sample) is taken and sent to a pathologist to determine if it is cancerous, and if so, the type.

If you had a biopsy, the pathologist will look at the sample as retrieved and frozen sections of it to characterize the tumor further. On your report, the sample will be described as either benign (non-cancerous) or malignant (non-cancerous). See below for more information on evaluating pathology reports after surgery for ovarian cancer.

Differential Diagnoses

A mass that is felt in the region of the ovary and fallopian tube on an exam or on imaging tests is referred to as an adnexal mass. A few of the possible causes (there are many) may include the following, which may all be considered in addition to ovarian cancer:

  • Ovarian cysts: Ovarian cysts are very common, but can often be distinguished from solid masses or complex cysts on ultrasound
  • Pelvic inflammatory disease (PID): With PID, an abscess may occur that causes a mass to be felt or seen.
  • Endometriosis: Endometriosis is a condition in which uterine tissue grows outside of the uterus.
  • Benign ovarian tumors: In general, tumors found in premenopausal women are more likely to benign while those found in postmenopausal women are more likely to be malignant.
  • Polycystic ovarian syndrome (PCOS): PCOS is a common condition in which women develop multiple cysts on their ovaries.
  • Corpus luteal cyst: It's not uncommon for women to develop a corpus luteum cyst in pregnancy.
  • Ectopic (tubal) pregnancy: Tubal pregnancies may cause findings similar to ovarian cancer, and when they occur early in pregnancy, women are sometimes unaware they are pregnant.
  • Ovarian torsion: This can lead to inflammation and bleeding and may occur on its own or secondary to an ovarian tumor.
  • Appendiceal abscess: If the appendix ruptures, it may cause an abscess near the region of the right ovary.
  • Pelvic kidney: This condition involves a kidney remaining in the pelvis during fetal development and may first be noticed as a mass in the pelvis.

Staging Tests

If a diagnosis of ovarian cancer is made, the next step is staging the tumor. Some of the information needed for staging may be gathered from imaging tests and a biopsy, but most often surgery (to remove the ovaries and often additional tissue) is needed to accurately stage the cancer. Figuring out the stage of a cancer is critical in choosing the best treatment options.

After surgery, your surgeon will send any tissue that was removed to a pathologist. This may include your ovaries, fallopian tubes, uterus, and tissue and biopsies taken from other regions of your abdomen. Under the microscope, she will confirm your diagnosis of ovarian cancer and also determine which samples contain cancer cells.

Both imaging tests and surgery can help determine if the cancer has spread to lymph nodes or other regions of the body. For advanced ovarian cancers, biopsies are usually taken from the lymph nodes, omentum (a fatty, carpet-like structure overlying the intestine), and often several areas of the peritoneum (the membranes that line the abdominal cavity). A surgeon will also remove or make note of any suspicious-looking nodules or other masses. If the cancer was mucinous, the appendix will be removed.

Washings may also be done, in which the surgeon injects saline into the abdomen and then withdraws the fluid to look for evidence of cancer cells.

Findings that help determine the stage include:

Type and subtype: Knowing the type and subtype of ovarian cancer can give information on the expected aggressiveness of a tumor and whether it is fast or slow growing.

Tumor grade: This is a measure of the tumor's aggressiveness. With endometrioid ovarian cancers, cancers are given a tumor grade between 1 and 3:

  • Grade 1: Cells are more normal looking (differentiated) and tend to be less aggressive. 
  • Grade 2: Cells fall between the above and below classifications.
  • Grade 3: Cells look very abnormal (undifferentiated) and tend to be more aggressive. 

Serous tumors are given one of two ratings instead: low grade or high grade.

Stages

Ovarian cancer is staged using either simplified or full FIGO staging methods. Findings may also be defined as borderline ovarian cancer. Though the below mostly concerns your physician, it may be helpful as you work to understand what treatment options may be appropriate for you.

Borderline Ovarian Cancer

Borderline ovarian cancers are those that have low malignant potential. These are usually early stage tumors and usually do not grow back after surgery. These tumors may be given a stage if your surgeon is uncertain during surgery whether higher grade cancer is present, or if it appears there was spread of the tumor.

Simplified Staging

To get a broad picture of the differences between stages, these can be broken down into:

  • Stage 1: The cancer is confined to the ovary.
  • Stage 2: The tumor has spread to pelvic organs (such as the uterus and fallopian tubes), but not to abdominal organs.
  • Stage 3: The tumor has spread to abdominal organs (for example, the surface of the liver or bowel) or lymph nodes (pelvic or abdominal nodes).
  • Stage 4: The tumor has spread to distant regions, such as the lungs, liver (inside not just the surface), brain, or distant lymph nodes.
  • Recurrent: Recurrent ovarian cancer refers to cancers that come back during or after treatment. If cancer comes back in the first three months, it is usually considered a progression rather than a recurrence.

Full FIGO Staging

The full FIGO, named for the International Federation of Gynecology and Obstetrics, is a surgical staging system that uses Roman numerals for stages (to estimate the prognosis) and letters for substages (which help guide treatment options).

  • Stage IA: The cancer is limited to one ovary and the outer ovarian capsule is not ruptured. There is no tumor on the external surface of the ovary and there is no ascites and/or the washings are negative.
  • Stage IB: The cancer is present in both ovaries, but the outer capsule is intact and there is no tumor on the external surface. There are no ascites and the washings are negative.
  • Stage IC: The cancer is either Stage IA or IB level, but the capsule is ruptured, there is a tumor on the ovarian surface, or malignant cells are present in ascites or washings.
  • Stage IIA: The cancer involves one or both ovaries and has extended on to the uterus and/or fallopian tube. The washings are negative washings and there are no ascites.
  • Stage IIB: The cancer involves one or both ovaries and has extended onto other pelvic tissues beyond the uterus and fallopian tube. The washings are negative and there are no ascites.​
  • Stage IIC: The cancer involves one or both ovaries and has extended to pelvic tissues like Stage IIA or IIB, but with positive pelvic washings.
  • Stage IIIA: Cancer has spread to the lymph nodes. The tumor is grossly (to the naked eye) confined to the pelvis but with microscopic peritoneal metastases (spread seen only under the microscope) beyond the pelvis to abdominal peritoneal surfaces or the omentum. The omentum is the fatty structure that drapes over the intestines and other abdominal organs.
  • Stage IIIB: Cancer has spread to the lymph nodes. This stage is similar to stage IIIA, but with macroscopic spread (spread that can be seen visually) to the peritoneum or omentum. At this stage, the areas of cancer that have spread are less than 2 cm (a little less than an inch) in size.
  • Stage IIIC: Cancer has spread to the lymph nodes. This stage is also similar to stage IIIA, but with peritoneal or omental metastases (spread) beyond the pelvis with areas that are larger than 2 cm (an inch) diameter in size, or with spread to lymph nodes in the groin (inguinal nodes), pelvis (pelvic nodes), or para-aortic (para-aortic nodes).
  • Stage IV: The cancer has spread to the body of the liver or to areas outside of the lower abdomen (the peritoneal cavity) to areas such as the chest or brain.
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