High-grade serous carcinoma (HGSC) is the most common type of ovarian cancer. It develops when cells in the ovaries, fallopian tubes, or peritoneum (lining of the abdomen) grow in an out-of-control manner.
Originally, doctors thought that ovarian cancer and fallopian tube cancer were two related but different cancers. Recently, however, researchers have discovered that many cases of HGSC begin growing in the fallopian tubes and later spread to the ovaries or peritoneum. Because of this, scientists usually group ovarian cancer, fallopian tube cancer, and primary peritoneal cancers together.
About 9 out of 10 cases of ovarian cancer are epithelial ovarian tumors. They develop in the epithelial cells found on the outer surface of the ovaries and fallopian tubes. Epithelial ovarian cancer is further divided into subtypes, the most common being serous cell carcinoma.
Doctors assign cases of ovarian cancer a grade based on how abnormal a person’s cells look and how fast those abnormal cells are growing. Serous cell carcinomas can be early-grade — cancer cells that look similar to normal ovarian cells. And they can be later-grade — cancer cells that look very abnormal and are rapidly growing in a disorderly way. Later-grade serous ovarian carcinoma can spread quickly and often leads to a poor prognosis (outlook). About 3 out of 4 people with ovarian cancer have HGSC.
Cancer develops when genes undergo changes. Genes tell cells what their jobs are and how to do them. Gene changes can cause cells to create abnormal proteins that force cells to grow too quickly, allow them to ignore signals that normally slow down growth, or make it difficult for cells to repair damage.
With HGSC, cells often have certain types of gene changes. In fact, 19 out of 20 people with this cancer have changes in a gene called TP53.
About 1 out of 4 people with HGSC have changes in their BRCA1 or BRCA2 genes. Such BRCA gene mutations cause additional damage to build up within cells. In general, BRCA mutations are usually passed down within families. Those who are born with changes in these genes are more likely to be diagnosed with both ovarian and breast cancers.
Most cases of ovarian cancer are not caused by inherited gene changes. They usually develop over the course of a person’s life. Certain environmental or lifestyle factors can increase the chances of these gene changes occurring, raising a person’s risk of cancer.
In general, ovarian cancer risk factors include:
Researchers have also found that people with pelvic inflammatory disease are more likely to develop the HGSC subtype. Additionally, people who have had breast cancer are 3 times more likely to develop HGSC.
On the other hand, giving birth, breastfeeding, and using oral contraceptives (birth control pills) can each reduce a person’s risk of ovarian cancer.
The symptoms of HGSC often don’t appear until cancer has grown and begun to spread.
People with symptoms may notice:
If you notice any of these potential symptoms of ovarian cancer, talk to your doctor. Often, they are caused by noncancerous conditions, but it is important to get any symptom checked out.
If your doctor suspects that you may have ovarian cancer, they may use several different tests to help them make a diagnosis.
Those tests may include:
In the laboratory, pathologists (doctors who specialize in studying tissues) analyze biopsy samples. Then they determine whether cells are cancerous and, if so, the type of ovarian cancer they represent. This is possible with high-grade serous ovarian cancer cells as they have a distinct appearance under a microscope. They also contain certain proteins not found in other types of ovarian cancer.
As for blood tests, a doctor may check the levels of the protein CA-125 in a person’s blood. Levels of this protein are often high in people with ovarian cancer.
When diagnosing ovarian cancer, doctors will assign a stage number using a staging system called FIGO (so-called as it’s based on the guidelines set by the International Federation of Gynecology and Obstetrics). This number describes how advanced the cancer is and how far it has spread in a person’s body. (Sometimes stages are referred to by Roman numerals. e.g., stage IV instead of stage 4.)
The FIGO stages for ovarian cancer are:
About 7 out of 10 cases of HGSC are at an advanced stage (stage 3 or stage 4) by the time they are diagnosed.
Doctors typically recommend a combination of treatment types, including surgery, chemotherapy, or targeted therapy. The treatments you receive may depend on your age, overall health, cancer stage, and whether you want to have children in the future.
Treatment for HGSC usually begins with surgery. During this procedure, a surgeon will try to remove as much cancer as possible. For early-stage tumors, this may involve removing a single ovary that contains a mass. For later-stage disease, surgery often includes removing multiple tumors and possibly parts of different organs or tissues that contain cancer. Doctors also can determine the stage of a person’s cancer during surgery. (Surgery itself may be called debulking surgery or cytoreductive surgery.)
Most people with HGSC receive chemotherapy drugs. These often include platinum-based drugs like Paraplatin (carboplatin) and Platinol (cisplatin), in addition to others like Taxol (paclitaxel) or Taxotere (docetaxel). People usually undergo at least six rounds of chemotherapy after surgery. In some cases, several rounds of chemotherapy may be given before surgery in an effort to shrink tumors before removing them. This is called neoadjuvant chemotherapy.
Targeted therapies may also be an option for cases of ovarian cancer that contain specific gene changes. Targeted therapy drugs may include Avastin (bevacizumab) — or poly (ADP-ribose) polymerase (PARP) inhibitors such as Lynparza (olaparib), Rubraca (rucaparib), and Zejula (niraparib).
If a person’s cancer goes away after initial treatments, they will still need regular follow-up visits with their health care team to look for signs that the cancer has relapsed (come back). These visits are critical, because most cases of HGSC eventually return. Relapsed cancer may be treated with a different chemotherapy regimen.
Clinical trials may also be an option for people with any stage of ovarian cancer. During a clinical trial, participants may be able to access new medications or treatment plans.
Because HGSC is usually not discovered until after it has begun to spread, it can be especially hard to treat. Overall, people with this type of ovarian cancer live an average of 3.4 years after being diagnosed. However, a person’s exact prognosis (medical forecast) depends on several other factors.
Your cancer stage is one such factor. People with early-stage ovarian cancer are more likely to live longer than those with advanced ovarian cancer.
Researchers have calculated survival rates across all subtypes of epithelial ovarian cancer:
Other factors also affect a person’s prognosis. People with HGSC who are less than 65 years old are more likely to live longer compared with those who are older. Those who are in better overall health, are not obese, or have less ascites (fluid in the abdomen) may also have a better outlook. If you’d like to know more about how your own characteristics affect your prognosis, talk to your health care team.
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