Types of Ovarian Cancer

Ovarian cancer is a heterogeneous (diverse) group of diseases. The most common type of ovarian cancer, epithelial ovarian cancer, tends to occur in women over the age of 50. This form of ovarian cancer the most publicized with the diagnosis. It is this form of cancer that most people think of when they hear the term "ovarian cancer". However, there are two other forms of ovarian cancer: germ cell tumors and stromal tumors

Ovarian cancers are divided into type 1 cancers and a more aggressive type 2 variant. Type 1 tumors are characterized by low-grade histology and more indolent behavior. These tumors include low- malignant potential tumors, low-grade endometrial and mucinous histologies, and clear cell tumors. Genetic alterations commonly include mutations in KRAS, BRAF, PTEN and PIK3CA. In contrast, studies have implicated serial genetic changes in the fallopian tubes as the actual site of origin for most type 2 serous epithelial ovarian tumors. These aggressive tumors are more common and are related to losses in TP53 and DNA repair capacity

Carcinoma in situ has been identified in tubal epithelium with early losses in the TP53 and BRCA1 / BRCA2 genes that characterize early tubal intraepithelial tumors. After these first two genetic events, further mutations in these transformed cells lead to tumor cell shedding, metastasis and invasion of cancer cells. These poorly differentiated type 2 ovarian cancer cells can then spread to the ovaries and peritoneal cavity, with the help of the ovarian cancer cells' affinity for the cells of the mesothelial lining

Epithelial Tumors

Serous cystadenomas Serous and mucinous cystadenomas are the most common benign epithelial ovarian neoplasms, originating from the reproductive cells of the ovaries. Most epithelial ovarian tumors are benign. However, cancerous epithelial tumors (also known as ovarian epithelial carcinomas) 

The classification of common epithelial tumors was developed by the World Health Organization and the International Federation of Gynecology and Obstetrics. The nomenclature takes into account cell type, tumor location and degree of malignancy, ranging from benign tumors to low-grade tumors and invasive carcinomas. Low-grade epithelial tumors ("borderline malignancy") have a much better prognosis than invasive carcinomas and are characterized by epithelial papillae with atypical cell clusters, cellular stratification, nuclear atypia and increased mitotic activity. Malignant tumors are characterized by an infiltrating destructive growth pattern with malignant cells that grow disorganized and dissect into the stromal planes. Invasive epithelial carcinomas are characterized by histologic type and grade (degree of cell differentiation)

Serous carcinoma 

Serous carcinoma is the most common type of epithelial ovarian cancer, accounting for over 50% of cases. The maximum age range is 45 to 65 years. Typical serous carcinomas show complex solid and papillary solid patterns and qualify as high-grade carcinomas

Endometrioid

Endometrioid carcinomas are seen in women between the ages of 40 and 50 and comprise approximately 10% -15% of ovarian cancers, of which approximately 6% are surface epithelial neoplasms. Endometrioid tumors are generally diagnosed as stage I disease and have a better prognosis than tumors with serous histology

Mucinous carcinomas

Mucinous carcinomas occur in women between the ages of 40 and 70 and account for approximately 12% of all ovarian cancers. The overall prognosis for mucinous carcinoma is better than for serous carcinoma because most patients have stage 1 disease

Clear cell carcinoma

Clear cell carcinoma comprises approximately 3% of epithelial ovarian cancers and approximately 8-10% of ovarian cancers in women, with a mean age of 57 years. Although clear cell carcinoma is the least common ovarian neoplasm, it is most often associated with paraneoplastic-related hypercalcemia

Germ Cell Tumors

Germ cell tumors, like their counterparts in the testis, are cancers of germ cells. These totipotent cells contain programming for the differentiation of nearly all types of tissue, and hence the germ cell tumors include a histologic menagerie of bizarre tumors, including benign teratomas (dermoid cysts) and a variety of malignant tumors, such as dysgerminoma, immature teratomas, yolk sac malignancies, and choriocarcinomas. Patients generally complain of abdominal pain and have an associated pelvic or abdominal mass. Others may have acute abdominal pain as a result of ovarian rupture, hemorrhage, or torsion

Teratoma

These germ cell tumors are either benign (mature) or cancerous (immature), and their cells can contain different types of tissue, such as hair, muscle, and bone. Immature teratomas are rare

• Mature Cystic Teratoma

Mature cystic teratomas, also known as dermoid cysts, are the most common benign ovarian neoplasms, with a peak incidence between the ages of 20 and 40. However, they can also be observed in infancy, as well as in menopausal women. Mature cystic teratomas originate from primordial germ cells and consist of

well differentiated derivatives of any combination of the three germ layers: ectoderm, mesoderm, endoderm. Ectodermal elements usually predominate. Although these mature tissues are benign in the vast majority of cases, on rare occasions they can undergo a malignant transformation, with squamous cell carcinoma being the most common malignant histology

•Immature Cystic Teratoma

Immature cystic teratoma is composed of tissues derived from all three germ layers, except that they also contain embryonic tissue, like a mature cystic teratoma. This group of cancers is the third most common germ cell malignancy, accounting for approximately 25% of all these cancers in patients under the age of 20. Unlike mature cystic teratoma, which occurs in all ages but more frequently during the reproductive years, immature cystic teratoma is found mainly during the first two decades of life. It usually grows rapidly through its capsule, forming adhesions to surrounding structures and implants in the peritoneal cavity

Dysgerminoma

Dysgerminoma is the most common germ cell malignancy of the ovary, accounting for 2% of all ovarian cancers. About 50% of patients with this cancer are under the age of 20 and 80% are under the age of 30. Children with dysgerminoma may have early puberty or primary amenorrhea. The serum level of lactate dehydrogenase is often elevated and can act as a tumor marker during treatment and follow-up

Endodermal sinus tumor

Endodermal sinus tumor, or yolk sac cancer, is the second most common germ cell cancer and accounts for 1% of all ovarian cancers. It can be pure or part of a mixed germ cell malignancy. The reported age distribution ranges from 16 months to 46 years, but the majority of patients are under the age of 30. The serum a-fetoprotein (AFP) level is frequently elevated in these patients, making it a useful diagnostic test in the initial assessment, assessment of response to treatment and in the follow-up of relapses. Symptoms are typical of those seen with other germ cell cancers. There have been several cases during pregnancy. No endocrine manifestations were observed with the pure Endodermal sinus tumor form. Over 70% of patients with endodermal sinus tumors are diagnosed with stage I, although they are biologically virulent

Choriocarcinoma

Choriocarcinoma is a rare, pure or mixed germ cell tumor. Pure choriocarcinoma is generally found in prepubertal children. Isosexual precocious puberty is a common clinical finding in premenarchical patients. In postmenarcheal patients, the presence of other germ cell components is useful in distinguishing ovarian germ cell tumors from a gestation choriocarcinoma

Ovarian Stromal Tumors

Ovarian stromal tumors or sex cord tumors are most common in women in their fifties or sixties, but the tumors can present at any age. About 7% of ovarian neoplasms are stromal tumors and tend to be diagnosed in stage I. These tumors are associated with hormonal effects, such as precocious puberty, amenorrhea and postmenopausal bleeding

These tumors arise from the mesenchymal components of the ovary, including steroid-producing cells and fibroblasts. Most of these tumors are indolent tumors with limited metastatic potential and present as unilateral solid masses. These tumors are mainly discovered by detecting an abdominal mass sometimes with abdominal pain due to ovarian torsion, intratumoral hemorrhage, or rupture. Rarely, stromal tumors can produce estrogen and present with breast tenderness,  as well as precocious puberty in children, menstrual disturbances in reproductively active women, or postmenopausal bleeding. In some women,  estrogen-associated secondary malignancies, such as endometrial or breast cancer, may present as synchronous malignancies

Thecoma

Thecoma is a benign tumor that affects all ages, mainly in the postmenopausal group, it is rare in patients under the age of 35. It accounts for 2% of all ovarian cancers. Many women with thecoma have abnormal or postmenopausal uterine bleeding, some have endometrial adenocarcinoma due to the uncontrolled estrogen produced by the tumor. Thecoma is composed of lipid-laden stromal cells that resemble theca cells. Rather than arising as a de novo neoplasm, it may represent changes occurring in underlying cortical stromal hyperplasia

Fibroma

Like thecoma, fibroma is a benign tumor or  that affects all ages, although most occur in women between the ages of 40 and 60, less than 10% of patients are 30 or younger.  Fibroma is not associated with hormone production. In some cases, hydrothorax and ascites are associated with a pelvic mass, a constellation of findings known as Meigs syndrome. In other cases, fibroma is seen in patients with an inherited basal cell nevus syndrome, characterized by early-appearing basal cell carcinomas, keratocysts of the jaw, calcification of the dura, and mesenteric cysts