Serous ovarian cancer is the most common histopathology subtype of epithelial ovarian cancer, accounting for approximately 70% of all cases. It falls under the category of epithelial adenocarcinoma, which comprises about 90% of all ovarian cancer diagnoses.
The disease is further classified by its “grade,” which describes how much the cancer cells resemble normal cells:
- Low-grade serous (Grade 1): These tumors are “well-differentiated,” meaning the cells look more like normal tissue. They are generally less aggressive, and early-stage patients may sometimes be managed with surgery and observation alone.
- High-grade serous (Grades 2 and 3): These are “poorly differentiated” cells that are highly aggressive and considered the most virulent. Most serous ovarian cancers are high-grade.
Key characteristics and clinical implications include:
- Genetic Factors: Germline mutations in tumor suppressor genes, specifically BRCA1, BRCA2, and TP53, play a significant role in the development of some serous ovarian cancers.
- Origin: While traditionally called “ovarian” cancer, high-grade serous carcinoma is now strongly believed to often originate as serous tubal intraepithelial carcinoma in the fallopian tubes before spreading to the ovaries and peritoneum.
- Treatment Intensity: Histology is a primary driver of treatment decisions. For example, in early-stage disease (Stage I), patients with high-grade serous histology are recommended to receive 6 cycles of chemotherapy (rather than 3) because they have a significantly lower risk of recurrence with the extended regimen.
- Prognosis: High-grade tumors are more aggressive than low-grade ones, making histology a critical factor in assessing a patient’s overall prognosis.