Doctors consider ovarian tumor size to stage a person’s cancer and choose their treatments. Smaller tumors do not always indicate early stage disease, and tumor size can impact treatment and outlook.

According to 2019 research, out of a group of 540 females, internal medicine doctors, gynecologists, and emergency medicine physicians were most likely to detect their ovarian cancer.

The authors found that females with early stage ovarian cancer most often had postmenstrual bleeding and a mass they could feel.

This article discusses ovarian tumor size and its impact on cancer staging. It also explains the different types of ovarian cancer tumors, cancer staging, treatment, and outlook.

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Doctors use tumor size to determine a person’s cancer stage, and the size of the tumor may influence what types of treatment a doctor may recommend.

When analyzing a sample, doctors look at the appearance of a person’s cells. If they look healthy, the doctor will describe them as well-differentiated. These cells will have a lower grade than those that do not look healthy, which doctors describe as poorly differentiated or undifferentiated.

  • Grade X: This means a doctor has been unable to assess the grade.
  • Grade 1: This refers to well-differentiated, low-grade tumors.
  • Grade 2: This grade is for moderately differentiated cells in intermediate-grade tumors.
  • Grade 3: This is for poorly differentiated, or high-grade, tumors.
  • Grade 4: This final grade is for undifferentiated, high-grade tumors.

The authors of 2018 research found that tumors can be larger in stage 1 ovarian cancer compared with stage 3. However, they note that these findings were from just two smaller studies and that more research is necessary.

The authors write that having a larger tumor in stage 1 disease may mean people seek a diagnosis more quickly, as their symptoms may be more noticeable and the tumors can be more visible on ultrasound scans.

Additionally, they found that the study participants with stage 1 cancer had a higher 5-year survival rate than those with stage 3 — 75% vs. 26%, respectively. This may suggest that tumor size does not always predict a person’s survival rate.

2022 research into ovarian cancer supports this, concluding that tumor size can be a useful way to assess a person’s outlook, although more research is necessary. The authors found that people with tumors up to 8 centimeters (cm) had better 5-year survival rates compared with those with larger tumors.

However, older research into other types of cancer, such as breast cancer, call certain facts into question. This includes whether a larger breast cancer tumor indicates more severe disease and a worse outlook.

Overall, experts require more research to determine how much tumor size affects a person’s cancer stage, outlook, and treatment options.

Doctors can classify ovarian tumors as one of three types:

  • Epithelial tumors: This type begins growing from the cells covering the ovary’s outer surface.
  • Germ cell tumors: A germ cell tumor begins to grow from the cells that produce eggs, or ova.
  • Stromal tumors: This type begins growing from cells that produce the hormones estrogen and progesterone and support the structure of the ovary, called the ovarian stroma.

Most ovarian tumors develop from epithelial cells.

However, not all tumors are cancerous. Ovarian tumors can also be:

  • Benign: Noncancerous tumors that never spread beyond the ovary.
  • Borderline: Slow-growing and less serious, borderline tumors do not grow into the ovarian stroma but can spread beyond it. These typically affect younger females.
  • Malignant: These are cancerous tumors.

Approximately 85%–90% of malignant ovarian cancer are epithelial ovarian carcinomas.

Ovarian cysts are not always cancerous. Cysts develop when fluid collects inside the ovary and are usually a normal part of ovulation. These are functional cysts that normally disappear after a few months without treatment.

However, cysts in females who do not ovulate, such as those who have not started their periods or older females experiencing menopause, can be cancerous.

A person should always see a doctor to check for ovarian cysts.

Learn more about the link between ovarian cysts and cancer.

Doctors use one of two systems to determine the stage of ovarian cancer: the FIGO (International Federation of Gynecology and Obstetrics) system and the AJCC (American Joint Committee on Cancer) TNM staging system. However, these systems are essentially the same.

The three factors these systems use to stage ovarian cancer include:

  • Tumor (T): This refers to the size or extent of the tumor and whether it is affecting the ovary, fallopian tube, or nearby organs, such as the uterus or bladder.
  • Nodes (N): This factor refers to whether ovarian cancer has spread to nearby lymph nodes in the pelvis or around the aorta, the main artery running from the heart to the pelvis.
  • Metastasis (M): Metastasis refers to whether ovarian cancer has spread to distant sites, such as to other organs, the bones, or fluid around the lungs, known as malignant pleural effusion.

Doctors will put numbers or letters after T, N, and M to denote how advanced the cancer is and to provide other insights. For instance, T1 means the cancer is present only in the ovaries or fallopian tubes while M0 means the cancer has not spread.

Doctors then group and assess all of this information to determine the overall stage of a person’s cancer.

If a doctor cannot get enough information about a person’s tumor, or if they cannot find evidence of a tumor, they will use the following categories:

  • TX: This means there is not enough information to assess the tumor.
  • T0: This means a doctor could not find evidence of a tumor.
  • NX: This means a doctor did not have enough information to assess the lymph nodes.

According to the American Cancer Society (ACS), staging can be clinical or surgical. Clinical staging considers the results of a physical exam, biopsy, and imaging tests. Doctors can do this before surgery.

Surgical staging involves a doctor examining tissue removed during surgery.

Doctors can also determine cancer staging after a person undergoes cancer treatment or if a person’s cancer comes back.

Typically, a person will have surgery and chemotherapy to treat ovarian cancer. However, a person may receive other treatments before or after surgery depending on the cancer stage and type of ovarian cancer.

Learn more about the treatments for ovarian cancer by stage.

The exact type of treatment a person receives may depend on:

  • the type of ovarian cancer
  • the stage of ovarian cancer
  • any other special considerations

The ACS writes that treatments for ovarian cancer may be local — only affecting the site of the tumor — or systemic — orally ingested or put into the bloodstream.

Local treatments include surgery and radiation therapy.

Systemic treatments include:

  • Chemotherapy: A person may have a combination of two chemotherapy drugs for ovarian cancer as it may be more effective. A person will generally have these through an IV (intravenously) every 3–4 weeks. Chemotherapy can shrink and get rid of tumors, although cancer cells may begin to grow again eventually.
  • Hormone therapy: This can include drugs, such as tamoxifen and aromatase inhibitors, which doctors usually use for breast cancer treatment. These drugs block the production of estrogen to stop cancer cells from growing.
  • Targeted drug therapy: This treatment aims to attack cancer cells and cause little damage to healthy cells. They can target the way cancer cells grow, divide, repair, and interact with other cells, stopping them from working properly.

There is a strong association between a person’s outlook and the stage of their disease at the time of diagnosis. A doctor may describe a person’s outlook in terms of a person’s 5- or 10-year survival rate.

Survival rates

The survival rate refers to the proportion of people who are still alive for a length of

time after receiving a particular diagnosis. For example, a 5-year survival rate of 50%

means that 50%, or half, of the people are still alive 5 years after receiving their diagnosis.

A relative survival rate helps give an idea of how long a person with a particular

condition will live after receiving a diagnosis compared with those without the condition.

For example, if the 5-year relative survival rate is 70%, it means that a person with the

condition is 70% as likely to live for 5 years as someone without the condition.

It is important to remember that these figures are estimates and are based on the

results of previous studies or treatments. A person can consult a healthcare

professional about how their condition is going to affect them.

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The chances of a person surviving at least 5 years after an ovarian cancer diagnosis depends on the type of tumor and how much it has spread.

5-year survival rates can be between 25–80% in people whose cancer has spread to other tissues.

Meanwhile, median 10-year survival rates are around 40–50%. This can jump to 70–92% for people with stage 1 cancer and drop to 6% in people with stage 4 cancer.

The ACS uses information from the SEER database to calculate survival rates based on people with ovarian cancer diagnoses between 2011–2017. Rather than using stages, this database uses the following groups when defining survival rates: localized, regional, and distant.

Localized ovarian cancer

If ovarian cancer has not spread outside of the primary tumor site, approximate relative survival rates are:

  • invasive epithelial ovarian cancer – 93%
  • ovarian stromal tumors – 97%
  • germ cell tumors of the ovary – 98%

Regional ovarian cancer

If ovarian cancer has spread outside of the ovaries to nearby tissues or lymph nodes, approximate relative survival rates may be:

  • invasive epithelial ovarian cancer – 75%
  • ovarian stromal tumors – 90%
  • germ cell tumors of the ovary – 94%

Distant ovarian cancer

If ovarian cancer has spread to parts of the body farther away from the ovaries, such as the liver or lungs, a person’s relative survival rates may be:

  • invasive epithelial ovarian cancer – 31%
  • ovarian stromal tumors – 70%
  • germ cell tumors of the ovary – 74%

The size of an ovarian tumor is an important factor that doctors consider throughout a person’s illness. Sometimes, later-stage cancers present with smaller tumors than early-stage cancers.

However, more research is necessary to investigate a definitive link between tumor size, cancer stage, and a person’s outlook.

The extent to which ovarian cancer has spread is also an important factor doctors consider when staging a person’s cancer and considering treatment for them.

Learn more about ovarian cancer with our dedicated content hub.