Types of ovarian cancer

There are several different types of ovarian cancer. The type of cancer depends on the type of cell and tissue the cancer starts in. There are three types of ovarian cancer: epithelial, germ cell and sex-cord stromal. Each of these has several subtypes. Some types of ovarian cancer are more common than others and affect women at different ages. 

Epithelial ovarian cancer

Epithelial ovarian cancer is the most common type of ovarian cancer, accounting for around 90%. It starts in the cells that lines or cover the ovaries and fallopian tubes (the epithelium). Not all epithelial tumours will be cancerous (malignant), some will be non-cancerous (benign). There are several subtypes of epithelial ovarian cancer:

• High grade serous ovarian cancer (sometimes known as high-grade carcinoma) is the most common type of epithelial ovarian cancer, accounting for more than half the cases of this type. Most of these tumours are thought to originate in the fallopian tube and are sometimes classified as fallopian tube cancers. They occur most often in women between the ages of 40 and 60 and are commonly treated with a combination of surgery and chemotherapy.

• Low-grade serous ovarian cancer (sometimes known as low-grade serous carcinoma) is a rare, slow-growing type of epithelial cancer that usually affects younger women between the ages of 45 and 55. This form of ovarian cancer is treated with surgery and chemotherapy, although it responds less well to chemotherapy. Some patients may benefit from hormonal therapy following chemotherapy.

• Endometrioid ovarian cancer accounts for around 20% of epithelial ovarian cancer cases. This type affects women of all ages, and it can be linked to endometriosis. It’s commonly treated with a combination of surgery and chemotherapy.

• Clear cell ovarian cancer (also known as clear-cell carcinoma) is a rare type of ovarian cancer, accounting for around 3-5% of epithelial ovarian cancers. It mainly affects women over the age of 50 and, like endometrioid ovarian cancer, it can be linked to endometriosis. This type is commonly treated with surgery and chemotherapy, although it responds less well to chemotherapy.

• Mucinous ovarian cancer tumours are rare and are generally found in women over the age of 50. These tumours can be non-cancerous (benign), borderline or cancerous (malignant). The tumours are usually removed by surgery, with or without chemotherapy. It doesn’t respond well to chemotherapy.

• Undifferentiated or unclassified tumours are the types of ovarian cancer that do not fit neatly into any category as it is not possible to tell which type of cell the cancer started in. They account for about 15% of epithelial tumours and are usually treated with a combination of surgery and chemotherapy.

• Brenner tumours are rare and only account for around 2% of epithelial ovarian cancers. They are generally non-cancerous (benign) and occur in women aged over 40. They are usually treated by removal during surgery.

• Ovarian carcinosarcoma are tumours that display a mix of epithelial (carcinoma) and stromal (sarcoma) characteristics. They are usually found in the uterus, but in rare cases they are found on the ovary. They are treated with a treated with a combination of surgery and chemotherapy. 

Germ cell ovarian cancer

Germ cell tumours are rare and account for around 5% of ovarian cancer cases. They usually affect younger women aged up to their early 30s. This type of cancer begins in the ovarian cells that develop into eggs (germ cells) and is often non-cancerous (benign). There are different subtypes of germ cell ovarian cancer:

• Mature teratomas are a common type of usually non-cancerous (benign) ovarian germ cell tumour. They are often called a dermoid cyst and commonly affect women anytime between teens and forties. The cyst is usually removed through surgery.

• Immature teratomas are cancerous (malignant) tumours that commonly occur at a much younger age. Teenage girls and women in their early 20s are most at risk of this kind of germ cell ovarian cancer. They are called immature because the cancer cells are at a very early stage of development. These types of tumours are commonly treated with surgery and chemotherapy, and outcomes are usually very good.

 Other types of cancerous (malignant) germ cell cancers include:

• Dysgerminomas tumours are rare and commonly affect women aged 15-45 years old.

• Mixed germ cell tumours are cancerous (malignant) ovarian tumours that are made from two or more types of germ cell tumours.

• Ovarian yolk sac tumour (also know as endodermal sinus tumour) that usually occur in children and younger adults. This type of tumour is commonly treated with surgery and chemotherapy.

These types of germ cell cancer are treated with surgery, possibly to remove the affected ovary, and chemotherapy. 

Sex cord stromal tumours

Sex-cord stromal tumours are rare, usually non-cancerous (benign), and found in the tissue that supports the ovary.

• Adult granulosa cell tumours usually occur early in the menopause and are slow growing. They can be treated by surgery alone to remove all the tumour with no need for chemotherapy. Hormonal treatment may be used for recurrent tumours.

• Juvenile granulosa cell tumours are rare and are usually seen in children and younger women. They are treated by surgery followed by a course of chemotherapy.

Sertoli-Leydig tumours (sometimes called androblastomas) are a rare type of sex-cord stromal tumour. This type of cancer is most common in women in their 20s and 30s and often associated with symptoms such as voice deepening and excessive hair growth on the face, chest and limbs. These symptoms are a result of the tumour producing the hormone testosterone. These tumours are usually non-cancerous (benign) and can be successfully removed by surgery, with no need for any further treatment. 

Primary peritoneal and fallopian tube cancer

Primary peritoneal and fallopian tube cancers are closely related to ovarian cancer and are often grouped together.  It is thought that most of the common epithelial ovarian cancers start at the end of the fallopian tube.  Cancer cells can travel to the ovaries or the peritoneum (a thin tissue that organs in the tummy) from the fallopian tubes. It can also be difficult for doctors to tell the difference between fallopian tube cancer and ovarian cancer that has spread to the fallopian tube.

• Primary peritoneal cancer is a rare cancer that is similar to epithelial ovarian and fallopian tube cancer and is usually treated in the same way (with surgery and chemotherapy). It starts in the peritoneum, (a thin tissue that supports the ovaries, fallopian tubes and other organs in the tummy), rather than the ovaries.

• Fallopian tube cancer starts in the fallopian tubes. Fallopian tubes connect the ovaries to the womb. This form of cancer is treated with surgery and chemotherapy. 

Borderline ovarian tumours

A borderline ovarian tumour has abnormal cells however, they are not cancerous and are usually removed with surgery. This type of tumour is not staged or graded. 

Reviewed: Oct 2022

Next review: Jan 2025