Stage III ovarian epithelial cancer represents an advanced form of the disease where cancer has moved beyond the pelvis into the abdominal cavity or to nearby lymph nodes. While this diagnosis can feel overwhelming, understanding the disease, its treatment options, and what to expect can help patients and their families navigate the journey ahead with greater confidence and clarity.

When doctors talk about stage III ovarian cancer, they are describing a situation where cancer cells have spread beyond the ovaries themselves. The cancer may have reached the peritoneum, which is the thin tissue lining that covers the organs inside the abdomen. It may also have traveled to the lymph nodes, which are small glands that help fight infection and remove waste from the body. Despite being called “ovarian” cancer, this type of disease can also start in the fallopian tubes or the peritoneum itself, and all three are treated in similar ways because they develop from the same type of tissue.^[1]

Stage III ovarian epithelial cancer is divided into smaller categories based on where exactly the cancer has spread and how large the tumors are. Stage 3A1 means the cancer has reached the lymph nodes at the back of the abdomen, and the size of cancer in those nodes determines whether it’s classified as 3A1(i) or 3A1(ii). Stage 3A2 indicates that cancer cells are present in the peritoneum and may also be in the lymph nodes. Stage 3B describes cancer growths in the peritoneum that are no larger than 2 centimeters, while stage 3C means there are cancer growths larger than 2 centimeters in the peritoneum, and cancer may also be on the surface of organs like the spleen or liver.^[1][3]

How Common Is Stage III Ovarian Epithelial Cancer?

Ovarian cancer is not the most common cancer affecting women, but it carries significant weight because it is often detected at an advanced stage. Epithelial ovarian cancer is by far the most frequent type, accounting for about 90 percent of all ovarian cancer cases. Among those diagnosed with epithelial ovarian cancer, the majority—around 60 percent—are found to have stage 3 disease at the time of diagnosis.^[5][8]

This late detection happens because ovarian cancer rarely causes noticeable symptoms in its early stages. The ovaries are located deep inside the pelvis, and small tumors can grow without causing pain or discomfort. By the time symptoms appear and prompt someone to see a doctor, the cancer has often already spread. This is one of the reasons why ovarian cancer is sometimes called a “silent” disease, and why regular exams and awareness of potential warning signs are so important.

The most aggressive subtype of epithelial ovarian cancer is called high-grade serous ovarian cancer, or HGSOC. It accounts for three out of every four epithelial ovarian cancers. Experts believe that HGSOC starts slowly in the fallopian tubes, but once it reaches the ovaries, it spreads quickly. Nearly 70 percent of HGSOC cases are stage 3 or 4 by the time they are diagnosed, meaning the cancer has already moved to nearby organs and lymph nodes.^[5]

What Causes Stage III Ovarian Epithelial Cancer?

The exact cause of epithelial ovarian cancer remains unclear. Scientists believe that many ovarian cancers actually begin in the cells at the ends of the fallopian tubes, and then spread to the ovaries. From there, the cancer can move into the peritoneum and to other parts of the abdomen. However, the precise reason why cells in the fallopian tubes or ovaries begin to grow abnormally is not fully understood.^[5]

What is known is that certain factors can increase a person’s risk of developing ovarian cancer. Age is one of the most significant factors. More than half of ovarian cancer diagnoses occur in people over the age of 65 who have gone through menopause. Family history also plays a role. Women who have close relatives—such as a mother, sister, or daughter—who have had ovarian cancer are at higher risk themselves.^[5]

Some ovarian cancers are linked to inherited changes in genes, particularly the BRCA1 and BRCA2 genes. These gene mutations are passed down through families and significantly increase the risk of both ovarian and breast cancers. Women who carry these mutations may consider preventive measures, such as surgery to remove the ovaries and fallopian tubes, to reduce their risk. Genetic testing can help identify whether someone carries these mutations, and the information can be valuable not only for the person being tested but also for their relatives.^[5]

Symptoms of Stage III Ovarian Epithelial Cancer

One of the challenges with ovarian cancer is that it rarely causes symptoms when it is in its earliest, most treatable stages. As the disease progresses to stage III, symptoms become more noticeable, but they can still be vague and easily mistaken for other, less serious conditions. This is part of the reason why so many cases are diagnosed at an advanced stage.^[5]

When epithelial ovarian cancer spreads into the peritoneum, fluid can begin to accumulate in the abdomen. This condition, called ascites, can cause the abdomen to swell and feel uncomfortable. Women may notice that their clothes feel tighter around the waist, or they may feel bloated even when they haven’t eaten much. This bloating is persistent and doesn’t go away with changes in diet or over-the-counter remedies.^[5]

Abdominal pain and pelvic pain are common symptoms of stage III ovarian cancer. The pain may be dull and constant, or it may come and go. Some women describe it as a feeling of pressure or fullness in the lower abdomen. Difficulty eating or feeling full quickly—even after eating just a small amount of food—is another symptom that can occur. Nausea and vomiting may also be present, especially if the cancer is pressing on the stomach or intestines.^[5]

Less common symptoms include changes in bowel habits, such as constipation or diarrhea, and urinary symptoms like a strong urge to urinate or needing to urinate more frequently than usual. Some women may also experience vaginal bleeding, though this is not as common as the other symptoms. Because these symptoms can be caused by many different conditions, it’s important to see a doctor if they persist or worsen over time.^[5]

How Is Stage III Ovarian Epithelial Cancer Diagnosed?

Diagnosing stage III ovarian epithelial cancer typically involves a combination of physical exams, imaging tests, blood tests, and surgery. When a woman presents with symptoms that suggest ovarian cancer, her doctor will usually start with a pelvic exam. During this exam, the doctor inserts gloved fingers into the vagina and presses down on the abdomen to feel the ovaries and other pelvic organs. This can help detect any abnormal growths or areas of swelling.

Imaging tests play a crucial role in diagnosing ovarian cancer and determining how far it has spread. An ultrasound of the pelvis, which may be done through the abdomen or through the vagina (transvaginal ultrasound), can create images of the ovaries and help identify tumors. A CT scan of the abdomen and pelvis provides more detailed images and can show whether cancer has spread to the peritoneum, lymph nodes, or other organs.

Blood tests are another important tool. One blood test that is commonly used is the CA-125 test, which measures the level of a protein called cancer antigen 125 in the blood. CA-125 levels are often elevated in women with ovarian cancer, although they can also be elevated for other reasons, such as endometriosis or even menstruation. Because of this, the CA-125 test alone cannot confirm a diagnosis of ovarian cancer, but it provides helpful information when combined with other tests.

In many cases, doctors cannot be completely certain of the diagnosis or the stage of the cancer until surgery is performed. During surgery, the doctor can directly see the extent of the cancer and take tissue samples for examination under a microscope. This process, called surgical staging, allows the doctor to determine exactly which substage of stage III the cancer falls into. The surgeon will also collect fluid from the abdomen and examine it for cancer cells.^[1]

Treatment Options for Stage III Ovarian Epithelial Cancer

Treatment for stage III ovarian epithelial cancer almost always involves a combination of surgery and chemotherapy. The specific treatment plan depends on several factors, including where the cancer has spread, whether the surgeon believes all the cancer can be removed, and the patient’s overall health and preferences. In some cases, targeted cancer drugs may also be used as part of the treatment.^[1]

Surgery

Surgery is usually the first step in treating stage III ovarian cancer. The goal of surgery is twofold: to determine the full extent of the cancer (staging) and to remove as much of the cancer as possible. The specialist surgeon who performs this type of surgery is called a gynaecological oncologist. During the operation, the surgeon will typically remove both ovaries, both fallopian tubes, and the uterus (including the cervix). This combination of procedures is called a hysterectomy with bilateral salpingo-oophorectomy.^[1]

In addition to removing these organs, the surgeon will aim to remove as much visible cancer as possible from the abdomen. This is called cytoreductive surgery or debulking surgery. The surgeon may need to remove parts of other organs if cancer has spread to them, such as portions of the intestines, the omentum (a fatty tissue in the abdomen), or even parts of the liver or spleen. The goal is to leave behind as little cancer as possible, ideally no visible cancer at all. Studies have shown that the more completely the cancer can be removed during surgery, the better the chances of long-term survival.^[1][8]

If the cancer has spread extensively or if a patient is not healthy enough to undergo major surgery right away, doctors may recommend starting with chemotherapy first. This approach, called neoadjuvant chemotherapy, can help shrink the tumors and make them easier to remove. After several rounds of chemotherapy, the patient then undergoes surgery, followed by more chemotherapy. This is known as interval cytoreductive surgery.^[1]

Chemotherapy

Chemotherapy uses powerful drugs to kill cancer cells or stop them from growing. For stage III ovarian cancer, chemotherapy is almost always part of the treatment plan. It may be given after surgery to destroy any remaining cancer cells (adjuvant chemotherapy), or before and after surgery (neoadjuvant chemotherapy with interval surgery).^[1]

The most common chemotherapy regimen for ovarian cancer combines two drugs: a platinum drug (such as carboplatin or cisplatin) and a taxane drug (such as paclitaxel or docetaxel). These drugs are usually given through an intravenous (IV) line, meaning they are delivered directly into a vein. The treatment is given in cycles, with each cycle followed by a rest period to allow the body to recover. A typical treatment plan might involve six cycles of chemotherapy, though the exact number can vary.^[1]

In some cases, chemotherapy may be delivered directly into the abdomen during surgery. This technique, called hyperthermic intraperitoneal chemotherapy or HIPEC, involves bathing the abdominal cavity with heated chemotherapy drugs. The heat is believed to help the chemotherapy penetrate the cancer cells more effectively. HIPEC is still being studied and is not yet considered standard treatment for all patients, but it may be an option at specialized cancer centers.^[1]

Targeted Cancer Drugs

Targeted cancer drugs are newer medications that work differently from traditional chemotherapy. Instead of attacking all rapidly dividing cells, targeted drugs focus on specific molecules that help cancer cells grow and spread. One such drug is bevacizumab, which targets a protein called vascular endothelial growth factor (VEGF). VEGF helps tumors build new blood vessels, which they need to grow. By blocking VEGF, bevacizumab can slow or stop tumor growth.^[3]

Bevacizumab may be given along with chemotherapy, or it may be given alone after chemotherapy is finished, sometimes for up to a year. Whether a patient receives targeted therapy depends on several factors, including the characteristics of the cancer and the patient’s overall health. Not all patients with stage III ovarian cancer will be candidates for targeted drugs, but they represent an important addition to the treatment options available.^[1]

When Surgery Isn’t Possible

In some situations, surgery may not be possible. This might be the case if the cancer has spread too extensively to be safely removed, or if the patient has other health problems that make surgery too risky. When surgery isn’t an option, chemotherapy can be given on its own. The goal in this case is to shrink the cancer as much as possible and to slow its growth, which can help relieve symptoms and improve quality of life.^[1]

Patients who cannot have surgery may also receive other treatments to help manage symptoms. For example, if fluid has built up in the abdomen (ascites), a procedure called paracentesis can be done to drain the fluid and relieve discomfort. If the cancer causes a bowel obstruction, surgery or other interventions may be needed to restore normal bowel function. Radiotherapy, which uses high-energy rays to kill cancer cells, may be used to relieve symptoms such as pain, though it is not commonly used as a primary treatment for ovarian cancer.^[1]

What Changes Happen in the Body with Stage III Ovarian Cancer?

Understanding what happens inside the body when ovarian cancer reaches stage III can help patients and their families make sense of symptoms and treatment. At this stage, the cancer has moved beyond the ovaries and is growing in the peritoneum, the thin membrane that lines the abdominal cavity and covers the organs inside it. Cancer cells can also travel through the lymphatic system to reach the lymph nodes, particularly those located behind the organs in the abdomen.^[1]

When cancer cells spread to the peritoneum, they can cause irritation and inflammation. This often leads to the production of excess fluid in the abdomen, a condition called ascites. The fluid causes swelling and discomfort, and it can press on the stomach and intestines, making it difficult to eat or causing nausea. The accumulation of fluid is one of the physical changes that patients with stage III ovarian cancer commonly experience.

Cancer in the peritoneum can also form nodules or tumor deposits on the surface of organs like the liver, spleen, or intestines. These deposits can interfere with normal organ function. For example, if cancer presses on the intestines, it can cause bowel obstruction, leading to constipation, cramping, and vomiting. If cancer affects the diaphragm (the muscle that separates the chest from the abdomen), it can cause pain that feels like it’s in the shoulder, because nerves in the diaphragm are connected to nerves in the shoulder area.

At the cellular level, ovarian cancer cells grow and divide more rapidly than normal cells. They also avoid the normal signals that would tell them to stop growing or to die. This uncontrolled growth allows the cancer to spread and form new tumors in different parts of the body. The cancer cells can also develop the ability to invade nearby tissues and to travel through blood vessels and lymphatic vessels, which is how they spread to distant sites.

The body’s immune system tries to fight the cancer, but cancer cells have ways of evading the immune response. They can produce substances that suppress the immune system or that help them hide from immune cells. This is one reason why ovarian cancer can be so difficult to treat. Targeted therapies like bevacizumab are designed to interfere with some of these processes, such as the cancer’s ability to build new blood vessels, which can help slow the growth and spread of the disease.

Outlook and Survival for Stage III Ovarian Epithelial Cancer

The outlook for stage III ovarian epithelial cancer varies depending on many factors, including the subtype of cancer, how much cancer can be removed during surgery, and how well the cancer responds to chemotherapy. Survival rates provide a general picture of how people with a certain type and stage of cancer fare, but they are based on large groups of people and cannot predict what will happen to any individual patient.

For invasive epithelial ovarian cancer diagnosed at stage III, the five-year relative survival rate is approximately 31 percent. This means that women with this diagnosis are about 31 percent as likely as women without the disease to be alive five years after diagnosis. However, these numbers are based on data from people diagnosed between 2012 and 2018, and treatments are constantly improving. Newer therapies and better surgical techniques may lead to improved survival rates in the future.^[3]

It’s important to remember that long-term survival is possible, even for women with advanced ovarian cancer. Studies have shown that about 31 percent of women diagnosed with ovarian epithelial cancer survive more than 10 years. Some of these long-term survivors had stage III or even stage IV disease at diagnosis. Factors associated with better survival include younger age at diagnosis, lower-grade tumors (meaning the cancer cells look more like normal cells under the microscope), and non-serous histology (a type of cancer other than serous). However, long-term survivors also include women with high-grade serous cancers, which shows that predicting individual outcomes is complex.^[22]

The amount of cancer that can be removed during surgery is one of the most important factors affecting survival. When surgeons are able to remove all visible cancer (a situation called “optimal debulking”), patients tend to have better outcomes than when cancer remains after surgery. This is why having surgery performed by a specialist—a gynaecological oncologist—is so important. These surgeons have the training and experience to perform extensive operations when necessary to remove as much cancer as possible.