Ovarian Cancer

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The Stages and Grades of Ovarian Cancer

Dr. Lisa Diver Stanford University

How Ovarian Tumors are Evaluated

  • The stage of a cancer, on a scale from 1 to 4, indicates whether or how far the tumor has spread from its initial location in the ovary
  • The grade of a cancer, on a scale from 1 to 4, is an evaluation of the tumor cells and how different they look from normal/benign ovarian cells

When a woman is diagnosed with ovarian cancer, there are all kinds of questions that she has about her diagnosis and treatment. But there are all kinds of questions her doctor has about the tumor, too. Doctors need a lot of information about a specific tumor before they can recommend the best course of treatment to eradicate it. Two vital pieces of information doctors require before deciding how to proceed are the tumor’s stage and its grade.

Staging a Tumor 

Tumors are staged to indicate how far they’ve spread from where they originated. “Stage 1, for example, means the tumor is still confined to the ovaries, whereas Stage 4 means that the tumor has spread to distance locations,” says Dr. Lisa Diver, gynecologic oncologist at Stanford University in the Bay Area.

The stages of ovarian cancer are:

  • Stage 1:  Cancer is confined to one or both ovaries
  • Stage 2:  Cancer has spread within the pelvis
  • Stage 3:  Cancer has spread to other organs in the abdomen
  • Stage 4:  Cancer has spread beyond the abdomen to other parts of the body

Doctors usually determine a tumor’s stage during surgery, where they can actually see the tumor, see where it’s growing, and check for distant or tiny metastases by removing tissue and examining it under the microscope.

Sometimes a cancer’s stage is determined by the results of a CT scan instead. “Before doctors go to the operating room for a suspected ovarian cancer, patients will have a CT scan of the chest, abdomen and pelvis,” explains Dr. Diver. If the CT scan reveals metastatic disease, the doctor may decide to prescribe chemotherapy before surgery—called neoadjuvant chemotherapy—to shrink the tumor before operating. “We can use the staging from the CT scan to substitute for surgical staging,” says Dr. Diver.

Grading a Tumor

Tumors don’t get grades of A, B, C or F like students. Instead they get numerical grades, much like the numerical grades for tumor staging. “Grade is a scale that pathologists determine by looking at tumor cells under the microscope,” says Dr. Diver. The grade of an ovarian tumor is an evaluation of how abnormal the cells are, and how different they look from normal/benign ovarian cells. The more abnormal a tumor’s cells are, the more aggressively growing the cancer is thought to be.

The grades of ovarian tumors are:

Grade 1: The cells are well differentiated, which means they closely resemble normal cells and are less likely to spread or come back after treatment.

Grade 2: The cells are moderately differentiated, meaning show increasing abnormality compared to normal cells. they are also more likely to spread and recur.

Grade 3: The cells are poorly differentiated, meaning they’re very abnormal compared to healthy ovarian cells. They are the most likely to spread and recur after treatment.

Unfortunately, because ovarian cancer has few symptoms in its early stages, it’s usually diagnosed at an advanced stage and grade. “The vast majority of ovarian cancer is high grade, and most commonly presents at stage three or four by the time it’s diagnosed,” says Dr. Diver.

But knowledge is power, and one key to winning any battle is to know your enemy. Knowing a tumor’s stage and grade gives doctors the information they need to fight it effectively.


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Dr. Lisa Diver is a gynecologic oncologist at Stanford University. Read More

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