Ovarian Cancer Staging: What You Need to Know

Ovarian cancer staging is more than just medical terminology — it’s the essential framework your ovarian cancer doctor and healthcare team use to understand your cancer and plan your treatment. 

When you receive a diagnosis, staging tells you and your doctors how far the cancer has spread, directly impacting your treatment path.

What Is Cancer Staging?

Cancer staging describes how much cancer is in your body and where it’s located. It answers critical questions: How extensive is the cancer? Has it spread? If so, where? These answers help your medical team determine the most effective treatment approach.

For ovarian cancer, doctors typically can’t determine the exact stage until surgery, when they can examine the full extent of the disease. This differs from other cancers, where staging may be completed through imaging alone.

What Is FIGO Staging for Ovarian Cancer?

FIGO staging for ovarian cancer refers to the system developed by the International Federation of Gynecology and Obstetrics. It’s the internationally recognized method for classifying the extent of ovarian cancer.

Your FIGO stage guides everything from ovarian cancer treatment options to prognosis. It provides the structure that helps make sense of this disease.

The FIGO staging system was updated in 2014 to include fallopian tube and primary peritoneal cancers alongside ovarian cancer. These three cancers are treated similarly, even though they originate in different locations. 

The update also expanded the staging classifications to be more precise. 

For example, Stage IC was further broken down into three subcategories: Stage IC1 (capsule rupture during surgery), Stage IC2 (capsule rupture before surgery or cancer on the ovary surface), and Stage IC3 (cancer cells found in abdominal fluid or peritoneal washings). 

These more detailed classifications help doctors better understand the specific characteristics of each patient’s cancer and tailor treatment plans accordingly.

What makes FIGO staging distinctive is that, when determining your stage, doctors consider not just the cancer’s location but also their surgical findings, including whether cancer cells are present in abdominal fluid (ascites). Ascites — the abnormal buildup of fluid in the abdomen — can be an important indicator of how far the cancer has spread and directly impacts staging decisions. 

Learn more: “Ascites and Ovarian Cancer: What You Need to Know”

Ovarian Cancer Stages

Let’s explore each stage of ovarian cancer, keeping in mind that every person’s cancer experience is unique.

Important note: Ovarian cancer survival rates have been improving steadily over the years due to advancements in treatment. While these rates are based on large population studies and serve as a general guide, they don’t necessarily reflect individual situations, and they do not definitively predict any one person’s journey with ovarian cancer. 

A gynecologic oncologist should be able to answer the patient’s questions and make a more accurate prognosis. They can also provide a more accurate assessment by taking into account personal circumstances and creating a tailored treatment plan. Factors such as the specific type of ovarian cancer, stage at diagnosis, overall health, and response to treatment all play a role in determining a person’s unique prognosis. With the support of a medical team and loved ones, individuals can navigate this challenging time with strength and resilience.

Stage I: The Early Stage

Stage I ovarian cancer means the cancer is only in the ovaries or fallopian tubes. It hasn’t spread to lymph nodes or distant sites. The size of the tumor also plays a crucial role in determining the specific subcategory within Stage I.

Stage I has three subcategories:

• Stage IA: Cancer is found in one ovary or fallopian tube only.
• Stage IB: Cancer is in both ovaries or fallopian tubes.
• Stage IC: Cancer is in one or both ovaries or fallopian tubes, plus one of these: the cancer capsule broke during surgery (Stage IC1), the capsule burst before surgery or cancer is on the ovary surface (Stage IC2), cancer cells are found in ascites or peritoneal washings (Stage IC3).

Only about 17% of ovarian cancers are detected at Stage I. When found this early, the 5-year survival rate is approximately 93%.

The primary treatment for Stage I is surgery, with some patients also receiving chemotherapy depending on cancer grade and type.

Stage II: Pelvic Spread

In Stage II, the cancer has grown beyond the ovaries and fallopian tubes but remains confined to the pelvis.

Stage II has two subgroups:

• Stage IIA: Cancer has spread to the uterus or fallopian tubes.
• Stage IIB: Cancer has spread to other pelvic tissues like the bladder or rectum.

Treatment typically includes a combination of surgery and chemotherapy for ovarian cancer. The surgery aims to remove all visible cancer, including the ovaries, fallopian tubes, uterus, and any other affected tissues in the pelvis.

Stage III: Abdominal Spread

Stage III means the cancer has spread beyond the pelvis to the abdominal cavity or lymph nodes in the abdomen.

Stage III has several subgroups:

• Stage IIIA1: Cancer has spread only to the retroperitoneal lymph nodes (lymph nodes along the major blood vessels at the back of the abdomen). This is further divided into:

• • Stage IIIA1(i): Metastases in retroperitoneal lymph nodes are 10 mm or smaller

• • Stage IIIA1(ii): Metastases in retroperitoneal lymph nodes are larger than 10 mm

• Stage IIIA2: Microscopic cancer is found on the peritoneal surfaces above the pelvic brim (the anatomic boundary dividing the pelvis), with or without retroperitoneal lymph node involvement.

• Stage IIIB: Visible cancer deposits up to 2 cm in size are found on the abdominal lining or the capsule (outer surface) of the liver or spleen, with or without retroperitoneal lymph node spread.

• Stage IIIC: Visible cancer deposits larger than 2 cm are found on the abdominal lining, with or without retroperitoneal lymph node spread.

Treatment for Stage III ovarian cancer typically involves debulking surgery (removing as much of the cancer as possible) followed by chemotherapy. In some cases, chemotherapy might be given before surgery to shrink the tumors.

Stage IV: Distant Spread

Stage IV means the cancer has spread to distant organs beyond the abdominal cavity.

It’s divided into:

• Stage IVA: Cancer cells are found in excess fluid accumulation around the lungs (pleural effusion). This is not a normal condition: The pleural space between the lungs and chest wall typically contains only a small amount of fluid, but with pleural effusion, abnormal amounts build up and contain malignant cells.
• Stage IVB: Cancer has spread to lymph nodes outside the abdominal cavity (including inguinal/groin lymph nodes) or to distant organs such as the inside of the liver or spleen, lungs, brain, skin, or bones. Essentially, this stage indicates spread to any location beyond the abdomen and pelvis.

Treatment approaches include chemotherapy, targeted therapies, and sometimes surgery if it’s possible to remove enough of the cancer to improve outcomes. The focus is often on controlling symptoms and improving quality of life.

Grades of Ovarian Cancer

While staging tells us where the cancer is, grading tells us how it looks under a microscope. This helps predict how the cancer might behave.

The grade reflects how abnormal the cancer cells appear and how quickly they’re likely to grow and spread. Higher-grade cancers tend to be more aggressive.

For most types of ovarian cancer, there are three grades:

• Grade 1 (Low Grade): Cancer cells look more like normal tissue and are well-differentiated. They tend to grow slowly.
• Grade 2 (Moderate Grade): Cancer cells look somewhat abnormal and are moderately differentiated.
• Grade 3 (High Grade): Cancer cells look very abnormal and are poorly differentiated. These tend to grow and spread more quickly.

For serous ovarian cancer — the most common type — doctors use a two-tier system:

• Low-grade serous ovarian cancer: LGSOC tends to grow slowly and often strikes women in their 40s and 50s (with the median age around 45 years old).
• High-grade serous ovarian cancer: HGSOC grows more aggressively and typically appears later in life, with most diagnoses occurring in women between 55 and 65 years old.

These different grading systems exist because research has shown that serous ovarian cancers behave as two distinct diseases with different causes, genetic changes, and responses to treatment.

How Is Ovarian Cancer Staged?

Ovarian cancer staging is primarily surgical. During surgery, the gynecologic oncologist:

• Removes the tumor(s)
• Takes tissue samples from multiple areas in the pelvis and abdomen
• Examines organs for signs of cancer spread
• Takes fluid samples from the abdomen

These samples are sent to a pathology lab where they’re examined under a microscope to confirm if cancer is present and determine the cancer’s grade.

In some cases, especially if surgery isn’t immediately possible, doctors might use a combination of physical exams, imaging tests (like CT scans or MRIs), and biopsies to assign a clinical stage. However, the final (pathologic) stage is determined after surgery.

Why Staging Matters for Treatment

Your cancer’s stage directly influences your treatment options and approach. Staging helps doctors develop the most effective plan for your specific situation.

Stage I: For very early cancers, especially low-grade Stage IA, surgery alone might be sufficient.

Women concerned about fertility may have options to preserve the unaffected ovary and uterus if the cancer is limited to one side.

High-grade tumors or cases with cancer cells in abdominal fluid typically need additional chemotherapy after surgery.

Stage II: At this stage, treatment becomes more comprehensive, with more extensive surgery required to remove visible cancer. Chemotherapy typically follows surgery to eliminate any remaining microscopic cancer cells.

Clinical trials may offer access to innovative treatments beyond standard protocols.

Stage III: Treatment strategies now integrate multiple approaches, primarily combining surgery with chemotherapy.

In some cases, doctors administer chemotherapy first to shrink tumors before attempting surgical removal.

Targeted therapy drugs might supplement traditional treatments, especially as maintenance therapy, to prevent recurrence.

Stage IV: At the most advanced stage, treatment priorities shift toward controlling the cancer while maintaining quality of life.

Chemotherapy remains a cornerstone of treatment, but timing is crucial based on your specific situation. The Society for Gynecologic Oncology (SGO) and American Society of Clinical Oncology (ASCO) have established evidence-based guidelines specifically for Stage IIIC and IV epithelial ovarian cancers, which represent 70 to 80% of all cases.

For patients whose tumors can likely be surgically reduced to less than 1cm, primary cytoreductive surgery followed by chemotherapy remains the standard approach. 

However, patients with Stage IIIC or IV epithelial ovarian cancer who have high clinical risk factors or a low likelihood of optimal surgical resection should receive neoadjuvant chemotherapy (NACT) first.

It’s important to understand that regardless of whether chemotherapy comes first or second, surgery is essential in ovarian cancer management. 

If you’re healthy enough for surgery, it will be part of your treatment plan. While imaging can suggest Stage III or IV disease and guide the decision to start with NACT, complete staging ultimately requires surgery. After NACT, interval debulking surgery is performed both to confirm staging and to remove as much tumor as possible. 

Without debulking surgery for ovarian cancer, it’s virtually impossible to achieve meaningful progression-free survival. Sometimes, the complete staging process isn’t fully achieved, but surgical debulking remains a critical component of treatment.

Beyond the Numbers: What Staging Means for You

While staging is crucial for medical decision-making, statistics are based on large groups of people and can’t predict exactly what will happen in your individual case.

Many factors beyond the stage affect prognosis, including:

• Your age and overall health
• The specific type of ovarian cancer
• The grade of the cancer
• How well the cancer responds to treatment
• Whether all visible cancer could be removed during surgery
• Genetic factors like BRCA and other types of ovarian cancer mutations

It’s so important to work with an experienced gynecologic oncologist who can develop a treatment plan tailored to your specific situation.

The Reality of Ovarian Cancer Staging: Why Early Detection Is So Hard

One of the most challenging aspects of ovarian cancer is that about 80% of cases are diagnosed at Stage III or IV. This occurs because early-stage ovarian cancer rarely causes noticeable symptoms.

When ovarian cancer symptoms do appear, they’re often subtle and easily attributed to other conditions:

• Bloating
• Pelvic or abdominal pain
• Feeling full quickly when eating
• Urinary frequency or urgency

By the time these symptoms become significant enough to prompt medical attention, the cancer has often already spread.

Unlike cervical cancer, which can be detected with Pap tests, or breast cancer, which can be found with mammograms, there’s no reliable ovarian cancer screening test for the general population.

Moving Forward After Staging

Learning about your cancer’s stage can be overwhelming. It’s normal to feel a range of emotions: fear, anger, sadness, or even relief at finally having answers.

Here are some steps that might help you move forward:

• Make sure you understand your diagnosis. Don’t hesitate to ask your doctor to explain things again or in different terms.
• Seek out a gynecologic oncologist if you haven’t already. These specialists have extensive training in treating ovarian cancer and stay up-to-date on the latest treatment approaches.
• Consider getting a second opinion. This is a standard practice for cancer treatment and can give you confidence in your treatment plan. In fact, most reputable oncologists encourage second opinions from other qualified medical doctors (MDs or DOs). Be cautious if your doctor seems resistant to you seeking another medical opinion — this could be a red flag. Note that we’re talking about opinions from board-certified physicians, not alternative practitioners like naturopaths or chiropractors. Your oncologist’s reluctance to recommend non-medical practitioners isn’t gatekeeping — it’s because evidence-based medicine offers your best chance for successful treatment.
• Ask about clinical trials. New treatments are constantly being developed and tested, and a clinical trial might give you access to promising new therapies. (Read about the benefits of ovarian cancer clinical trials.)
• Connect with others who understand. Support groups — either in-person or online — can provide valuable emotional support and practical advice from those who have been in your shoes.
• Take care of your whole self. Cancer affects more than just your physical health. Pay attention to your emotional and mental well-being, too.

Ovarian Cancer Staging is One Piece of the Puzzle

Ovarian cancer staging guides treatment decisions and helps predict outcomes. Understanding your stage empowers you to ask informed questions and actively participate in your care.

Remember that staging is just one piece of your unique cancer puzzle. The science of ovarian cancer is evolving rapidly, with new insights leading to more personalized treatment approaches.

If you or someone you love has been diagnosed with ovarian cancer, know that you’re not alone. Many women face this diagnosis and find strength through their medical teams, support networks, and the knowledge that treatment options continue to improve.