Understanding the Basics

Ovarian cancer begins when abnormal cells in the ovaries grow and multiply uncontrollably, forming tumors. The ovaries are two small organs in the female reproductive system that produce eggs and hormones such as estrogen and progesterone.

Although ovarian cancer is one of the most serious gynecologic malignancies, it’s not a single disease. It’s actually a group of cancers that differ by cell type, aggressiveness, and response to treatment.

Doctors classify ovarian cancer mainly based on where the cancer cells originate within the ovary. The three primary types are:

  1. Epithelial tumors – develop from the surface layer of the ovary.

  2. Germ cell tumors – begin in the egg-producing cells.

  3. Stromal tumors – arise from the tissue that holds the ovary together and produces hormones.

Each behaves differently and requires a unique treatment approach. Understanding the differences helps guide early detection and effective therapy.

Epithelial Ovarian Cancer

Epithelial ovarian cancer is the most common form, accounting for about 85–90% of all ovarian cancers. It develops from the thin layer of cells that covers the outside of the ovaries.

This type is typically diagnosed in women over 50 and often discovered at a later stage because symptoms—such as bloating or pelvic discomfort—are nonspecific.

Subtypes of Epithelial Tumors

There are several subtypes of epithelial ovarian cancers, each with distinct cellular characteristics and behaviors:

  • Serous carcinoma:
    The most frequent subtype, responsible for about 70% of epithelial cases. It is divided into two forms:

    • High-grade serous carcinoma (HGSC) – fast-growing and often linked to BRCA1 or BRCA2 gene mutations.

    • Low-grade serous carcinoma (LGSC) – slower-growing but resistant to standard chemotherapy.

  • Endometrioid carcinoma:
    Often associated with endometriosis, this cancer resembles the cells that line the uterus. It tends to have a better prognosis when caught early.

  • Clear cell carcinoma:
    Known for its resistance to chemotherapy, it is more common in women of Asian descent and often linked to endometriosis.

  • Mucinous carcinoma:
    Produces mucus-like material. Though rare, it may be confused with cancers that start in the digestive tract, so proper diagnosis is crucial.

  • Transitional cell carcinoma (Brenner tumor):
    A rare subtype resembling bladder cells. Most Brenner tumors are benign, but a small fraction can be malignant.

Treatment and Outlook

The main treatments include:

  • Surgery: Removing ovaries, fallopian tubes, uterus, and visible tumor masses.

  • Chemotherapy: Typically platinum-based regimens like carboplatin and paclitaxel.

  • Targeted therapy: PARP inhibitors and angiogenesis blockers like bevacizumab for BRCA-positive or advanced cases.

Prognosis depends on the stage and subtype. High-grade serous carcinomas have lower survival rates, while endometrioid and low-grade serous types fare better when detected early.

Germ Cell Ovarian Cancer

Germ cell tumors are much less common, representing about 5% of ovarian cancers. These cancers begin in the cells that form the eggs inside the ovaries.

Unlike epithelial cancers, germ cell tumors often affect younger women, including teenagers and women in their 20s. Fortunately, most of them are highly treatable, even if discovered after they spread.

Common Germ Cell Subtypes

  • Dysgerminoma:
    The most frequent malignant germ cell tumor, similar to testicular seminoma in men. Dysgerminomas grow slowly and are very responsive to chemotherapy and radiation.

  • Endodermal sinus tumor (yolk sac tumor):
    Usually aggressive but responds well to combination chemotherapy. Often produces a tumor marker called AFP (alpha-fetoprotein), which helps in diagnosis and monitoring.

  • Immature teratoma:
    Composed of tissues resembling bone, hair, or skin. The “immature” variant contains embryonic cells and can behave aggressively.

  • Choriocarcinoma:
    A rare and fast-spreading cancer producing high levels of hCG (human chorionic gonadotropin), a hormone also found in pregnancy.

  • Embryonal carcinoma:
    Another rare type, often mixed with other germ cell tumor forms.

Treatment and Prognosis

Standard treatment involves fertility-sparing surgery when possible (removing only one ovary) followed by chemotherapy.

Because germ cell tumors are sensitive to drugs, survival rates are high—up to 90–95% for localized disease. Even advanced cases have strong recovery potential with modern treatments.

Stromal Ovarian Cancer

Stromal tumors are rare, accounting for less than 5% of all ovarian cancers. They develop from the connective tissue that holds the ovaries together and produces female hormones.

These cancers are usually detected earlier because they often cause hormone-related symptoms such as:

  • Abnormal uterine bleeding

  • Breast tenderness

  • Menstrual irregularities

  • Early puberty in young girls

Major Stromal Subtypes

  • Granulosa cell tumors:
    The most common stromal type. These tumors often secrete estrogen, leading to early signs of hormonal imbalance.

  • Sertoli-Leydig cell tumors:
    Rare tumors that produce androgens (male hormones), which can cause masculinizing effects such as deepened voice or facial hair growth.

  • Fibrosarcomas and thecomas:
    Usually benign or slow-growing; malignant forms are rare.

Treatment and Outlook

Surgery is the main treatment. If the cancer has spread, chemotherapy or hormone therapy may be added.

Because stromal cancers grow slowly, the long-term outlook is better than for epithelial types, especially when diagnosed early.

Borderline Ovarian Tumors

Borderline tumors, also known as low malignant potential tumors, are unique because they don’t invade nearby tissues aggressively like other ovarian cancers.

They typically affect women in their 30s or 40s and have an excellent prognosis. Most are of the serous or mucinous type.

Features of Borderline Tumors

  • The cells look abnormal under the microscope but don’t deeply invade the ovarian tissue.

  • They can recur after treatment but rarely spread to distant organs.

  • These tumors are often discovered during routine imaging or surgery for benign cysts.

Treatment and Prognosis

Surgical removal is usually enough. Many patients retain fertility if only one ovary is affected. Chemotherapy is not typically required.

The 5-year survival rate is over 95%, but long-term follow-up is recommended because recurrence may occur years later.

Primary Peritoneal Carcinoma

Although it doesn’t start in the ovaries, primary peritoneal carcinoma (PPC) behaves almost exactly like epithelial ovarian cancer.

It arises from the lining of the abdominal cavity (peritoneum), which has cells similar to those covering the ovaries. This type can occur even in women who have had their ovaries removed.

Symptoms

  • Abdominal bloating and pain

  • Nausea, indigestion

  • Weight changes

  • Fluid buildup in the abdomen (ascites)

Treatment

Treatment mirrors that of epithelial ovarian cancer:

  • Surgery to remove as much tumor as possible

  • Chemotherapy, usually with carboplatin and paclitaxel

  • Targeted therapy to slow tumor growth

PPC tends to respond well to the same treatments as advanced epithelial cancers, though early detection remains challenging.

Fallopian Tube and Peritoneal Origins

Recent research has shown that many so-called “ovarian” cancers may actually begin in the fallopian tubes. Tiny precancerous lesions in the fimbriae (ends of the tubes) can spread to the ovaries and abdomen.

This discovery has changed the way doctors think about prevention and early detection. For women with BRCA1 or BRCA2 mutations, doctors may recommend removal of fallopian tubes (salpingectomy) while preserving the ovaries until later.

Genetic Links and Hereditary Syndromes

About 10–15% of ovarian cancers are hereditary. The most well-known genetic links include:

  • BRCA1 and BRCA2 mutations:
    Dramatically increase the risk of both breast and ovarian cancers.

  • Lynch syndrome:
    Associated with mutations in DNA mismatch repair genes, leading to a higher risk of ovarian, uterine, and colorectal cancers.

Women with strong family histories should undergo genetic counseling and testing. Preventive surgeries and regular screenings can significantly reduce risk.

Diagnosis and Testing

Diagnosing the type of ovarian cancer involves a combination of imaging, lab tests, and surgery:

  • Pelvic exam and ultrasound: Identify masses or cysts.

  • CT or MRI scans: Evaluate the extent of disease.

  • Blood tests: CA-125, AFP, hCG, and LDH levels depending on the suspected tumor type.

  • Surgical biopsy: The definitive way to confirm diagnosis and type.

Accurate typing is critical because treatment strategies vary widely between epithelial, germ cell, and stromal tumors.

Treatment Overview

While surgery and chemotherapy remain the backbone of treatment, advances in targeted therapy have improved survival rates across all types.

Treatment modalities include:

  • Surgery: For removal of the tumor and staging.

  • Chemotherapy: Especially for epithelial and germ cell cancers.

  • Targeted therapy: Focuses on molecular pathways specific to tumor types.

  • Hormone therapy: Effective for hormone-producing stromal tumors.

  • Immunotherapy: An emerging option in clinical trials for advanced cases.

Prognosis by Type

The outlook for ovarian cancer varies greatly depending on type and stage:

  • Epithelial: Often detected late; 5-year survival around 45%.

  • Germ cell: Highly treatable; survival exceeds 90%.

  • Stromal: Slower growth; 70–80% 5-year survival.

  • Borderline: Excellent prognosis; over 95% long-term survival.

Early diagnosis and personalized therapy significantly improve these outcomes.

Research and Future Directions

Scientists are exploring new frontiers in ovarian cancer research, including:

  • Early detection biomarkers to catch disease before it spreads.

  • Immunotherapy and vaccine development targeting tumor antigens.

  • Genomic profiling to tailor treatments for individual patients.

  • Maintenance therapy using PARP inhibitors to prevent recurrence.

The future of ovarian cancer care is shifting toward precision medicine, offering hope for better survival and improved quality of life.

Key Takeaways

  • Ovarian cancer is not one disease but several distinct types.

  • Epithelial is the most common; germ cell and stromal are rarer but more curable.

  • Knowing the cancer type guides treatment decisions and improves survival.

  • Genetic testing and early screening play vital roles in prevention.

Understanding your diagnosis empowers you to make informed choices and seek the best possible care.