Ovarian Cancer Canada

Western Regional Blog – BC, YK, AB, NWT and Nunavut

Differential Diagnosis and Clinical Relevance of Ovarian Carcinoma Subtypes

“Over the next 5 years, we will see a dramatic surge forward in our understanding of the molecular basis of the less-common subtypes of ovarian carcinoma (LGSC, EC, MC and CCC), which together account for 30% of cases. There will be increasing efforts to offer subtype-specific treatment for ovarian carcinoma, based on our improved understanding of the different biologies of these subtypes.” 

Chris M.J. Conklin, MD; C. Blake Gilks, MD, FRCPC



The five main subtypes of ovarian surface epithelial carcinoma (high-grade serous, low-grade serous, endometrioid, clear cell and mucinous) are different diseases, with differences in genetic and environmental risk factors, precursor lesions, molecular events during oncogenesis, patterns of spread and response to treatment. With recent advances in surgical pathology, it is possible to reproducibly diagnose these subtypes in routine surgical pathology practice. This review examines these subtypes of ovarian carcinoma, focusing on differential diagnosis, molecular features and current treatment strategies. The increasing understanding of the molecular abnormalities associated with each subtype is leading to exploration and introduction of more subtype-specific treatment of ovarian carcinoma.

Key Issues – 

  • Ovarian surface epithelial carcinomas are the most common malignant ovarian tumors and the most lethal gynecological malignancies.
  • Advances in immunohistochemistry and molecular analyses have dramatically increased the diagnostic accuracy of ovarian surface epithelial carcinoma subtype diagnosis.

More than 98% of ovarian surface epithelial carcinomas can be assigned to one of five major subtypes: high-grade serous carcinoma, clear cell carcinoma, endometrioid carcinoma, mucinous carcinoma and low-grade serous carcinoma. The five main subtypes have distinct molecular abnormalities and treatment responses, and are best regarded as distinct diseases.

  • New subtype-specific treatment strategies are being developed, targeting molecular abnormalities specific for each subtype.
  • Poly (ADP-ribose) polymerase P inhibitors have shown promise in the treatment of high-grade serous carcinoma, through exploitation of inherent double-strand break–repair defects.
  • MAPK inhibitors have been tested in low-grade serous carcinoma, PIK3CA inhibitors in clear cell carcinoma, tamoxifen in endometrioid carcinoma and Herceptin® in mucinous carcinoma, with varying results.
  • Further subtype-specific therapeutic trials are required to improve outcomes for patients with ovarian carcinoma.


This entry was posted on May 17, 2013 by in Research Updates and tagged , .

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