Stages and grades of ovarian cancer

When you're diagnosed with ovarian cancer, your medical team will aim to identify how much cancer there is, if it has spread to other parts of your body, and how fast it's likely to grow.

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When you’re diagnosed with ovarian cancer, your medical team will want to find out:

  • the size of the cancer (tumour) and if it has spread to other parts of your body, beyond the ovaries. This is called the stage.
  • which part of the ovary it comes from and what type of cells the tumour has grown from. This is called the type of ovarian cancer.
  • how different the cancer cells look compared to normal cells. This is called the grade.

Understanding the stage, type and grade of the cancer can help you when talking about your diagnosis and treatment plan with your medical team.

Stages

Finding out the stage of the cancer is an important part of your diagnosis because it impacts your treatment options. To find out the stage of the cancer your treatment team will:

  • use scans such as a CT or MRI scan
  • examine you during surgery

An international system of staging uses a number from 1 to 4 to describe how much cancer there is and if it has spread. You can read through what each stage means in the stages tool below. For ovarian cancer, the staging system is called the FIGO system. It stands for the Fédération Internationale de Gynécologie et d'Obstétrique, known as the International Federation of Gynaecological Oncologists in English.   

Fallopian tube cancer is also staged from 1 to 4. Primary peritoneal cancer is staged as either early or advanced rather than with the FIGO system of numbers. Both of these cancers are treated in a similar way to ovarian cancer because they behave in the same way and respond to similar treatments.

Use the stages tool below to find out what the different stages and substages of ovarian cancer mean. The tool shows staging for tumours that start in the ovaries and/or fallopian tubes. It doesn’t show the staging of primary peritoneal cancer.

To get started, click on the tabs along the top.

If you have any questions about the stages of ovarian cancer and what it means for your treatment options, our specialist nurses are here for you. Our support line is open Monday-Friday, 9-5pm. Call us on 0808 802 6000

Grades

The grade describes how different the cancer cells look compared to normal cells. It can help predict how the cancer will behave. This includes how fast it is likely to grow or spread which may impact the treatments recommended for you. To find out the grade, your treatment team will take a sample of cancer cells and look at them under a microscope.

In the most common type of ovarian cancer (epithelial ovarian cancer), tumours are simply divided into low-grade and high-grade, and a grading number isn’t given:

  • High-grade serous is the most common type of ovarian cancer. It is usually treated with a combination of chemotherapy and surgery. It generally responds well to chemotherapy.
  • Low-grade serous is a less common type of epithelial ovarian cancer. It generally does not respond as well to chemotherapy. It is usually slower growing than high-grade serous ovarian cancer. Surgery is the most effective treatment although chemotherapy and hormone therapy are also used.

All other types of ovarian cancers, that are not epithelial, are graded as 1, 2 or 3:

  • Grade 1 (well-differentiated) means the cancer cells look similar to normal cells. They usually grow slower and are less likely to spread or recur (come back).  
  • Grade 2 (moderately differentiated) cancers and grade 3 (poorly differentiated) cancers show increasing difference of appearance compared to normal cells. They are also more likely to spread or recur (come back).  

Healthy cells change in structure and develop for their specific role in the body. This process is known as differentiation. Well-differentiated cancer cells are highly specialised for their role and place and look more similar to healthy cells. For example, if they are ovarian cells they would look more similar to a healthy ovary cell. Poorly differentiated cancer cells have not gone through a differentiation process and look very different to healthy cells. 

More information and support

Find out more

Rachel and Val Target Ovarian Cancer nurse advisers

Our support line is open Monday-Friday, 9am–5pm

Speak to our specialist nurses

Last reviewed: May 2025

Next review: May 2028

To learn more about our review process, take a look at our information standards.

References

Below is a sample reference used for this article, you can request the full list by emailing [email protected]

  • FIGO, International Federation of Gynaecology and Obstetrics. Accessed: 15.3.25.