Ovarian Cancer Basics

Ovarian cancer develops when cells in the ovary start to divide and grow uncontrollably. Normally, cells divide only when additional cells are required for normal body function. However, sometimes the genomic regulators of cell division stop functioning. This results in a disordered accumulation of cells that eventually grow into a mass called a tumor.

Not all tumors are cancerous. Tumors that are cancerous have one or more of these three properties:

  • Uncontrolled cell growth (division beyond the normal limits)
  • Cell invasion (intrusion on and destruction of adjacent tissues)
  • Metastasis (cells spread to other locations in the body via lymph or blood)

These three properties differentiate malignant (cancerous) tumors from benign tumors, which are self-limited, do not invade, and do not metastasize.

Types of Ovarian Cancer

There are three main types of ovarian cancer, which are distinguished by the type of ovarian cells in which they start.

  • Epithelial ovarian tumors, which are derived from the cells on the surface of the ovary or fallopian tube;
  • Germ cell ovarian tumors, which are derived from the cells that produce eggs; and
  • Cord-stromal cell ovarian tumors, which are derived from the connective tissue within the ovary.

Epithelial Ovarian Cancer Subtypes

Epithelial ovarian tumors are further classified into subtypes based on the type of epithelial differentiation that is present in the tumor. The primary subtypes, also referred to as histology types, are serous, mucinous, endometrioid and clear cell and derive their names from the tissue that they most closely resemble. The serous histology is the most common and is found in 75-80% of patients with epithelial ovarian cancer.

In addition to looking like different types of epithelial tissues, the tumor histology types also differ from each other at the molecular level. These differences are important to consider when deciding among therapy options. Clearity uses information about these molecular differences to generate a Tumor Blueprint.