What are the More Rare Types of Ovarian Cancers?

What are the More Rare Types of Ovarian Cancer?
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In the United States, ovarian cancer is the second most common gynecologic cancer, with an estimated 21,290 new cases in 2015. The most common gynecologic cancer is uterine cancer, with an estimated 54,870 new cases this year. Even though it is not the most common type of gynecologic cancer, ovarian cancer is the most deadly.

Usually, when someone uses the term “ovarian cancer,” they are referring to epithelial ovarian cancer.

These are cancers that arise from the epithelial lining of the ovary, and this type of ovarian cancer makes up 95% of all ovarian cancers.

The more rare ovarian cancers include those known as germ cell tumors and sex-cord stromal tumors.

Sex-Cord Stromal Ovarian Tumors

Ovarian sex-cord stromal tumors can be either benign or malignant. They develop from the dividing cells that would normally give rise to the cells that surround the oocyte (egg). These are rare ovarian tumors, making up just over 1% of all ovarian cancers. There are several subtypes of these sex-cord stromal tumors. Some of these include fibromas, fibro-thecomas, granulosa cell neoplasms, and Sertoli-Leydig cell tumors.

While the average age of a woman diagnosed with the more common epithelial ovarian cancer is around 61, women diagnosed with sex-cord stromal ovarian tumors tend to be younger, around age 50. Also, while the more common epithelial ovarian cancer tends to be diagnosed at a later stage, often stage III or IV, women with sex-cord stromal tumors tend to be diagnosed at earlier stages, often stage I or II.

Some sex-cord stromal tumors secrete proteins or hormones. These may include inhibin, estrogen, and androgens. Sometimes, these can be helpful in the diagnosis of these rare tumors.

Ovarian Germ Cell Tumors

Ovarian germ cell tumors start in the ovarian germ cells (eggs), and they can be benign or malignant.

These are more common than sex cord stromal ovarian tumors but still rare, making up only 5% of malignant ovarian cancers.

Unlike epithelial ovarian cancer, women with ovarian germ cell tumors tend to be younger at diagnosis. They typically occur in young women between the ages of 10 and 30.

There are several different types of ovarian germ cell tumors. Some of them include teratomas (also called dermoid cysts), endodermal sinus tumors (also called yolk sac tumors), dysgerminomas, embryonal carcinomas, and mixed germ cell tumors. Mixed germ cell tumors often contain elements of teratoma, yolk sac, dysgerminoma, and/or embryonal carcinoma. Benign teratomas are the most common ovarian germ cell tumor.

Ovarian germ cell tumors often grow rapidly. However, despite that, women with these types of tumors often present with early stage (stage I) disease.

Ovarian germ cell tumors are often associated with various tumor markers, including hCG, AFP, and lactate dehydrogenase (LDH).  Similar to the use of CA 125 in epithelial ovarian cancers, these markers can often be used to follow response to treatment.

These markers may also be helpful in the diagnosis of various types of ovarian germ cell tumors.

Treatment of Sex Cord Stromal Tumors and Ovarian Germ Cell Tumors

The primary treatment for both of these rare types of ovarian tumors is surgery. Surgery is performed for three reasons -- to make the diagnosis, to determine the stage, and as the mainstay of treatment. Sometimes, chemotherapy may be used, but this approach depends heavily on the type of tumor (for example, whether benign or malignant) and the stage of the tumor.

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