SNP Shot: Genomic Insights

Ovarian cancer is a disease affecting women, characterized by abnormal cells in the ovary multiplying uncontrollably to form a tumor. The ovaries are the female reproductive organs responsible for producing egg cells. It commonly occurs after age 40, with the majority of cases appearing after age 60.

The most prevalent type of ovarian cancer originates in epithelial cells, which line body surfaces and cavities. These cancers can develop from epithelial cells on the ovary's surface. Research suggests many, if not most, ovarian cancers may start in the epithelial cells of the fimbriae, located at the end of the fallopian tubes, with the cancerous cells then migrating to the ovary.

Cancer can also arise in the epithelial cells lining the abdomen (peritoneum), resulting in primary peritoneal cancer. This form of cancer closely resembles epithelial ovarian cancer in its origin, symptoms, progression, and treatment. Primary peritoneal cancer frequently spreads to the ovaries and can even occur after their removal. Given the similarities and easy spread between cancers originating in the ovaries, fallopian tubes, and peritoneum, they are often challenging to differentiate and are generally considered as a group by experts.

In approximately 10% of cases, ovarian cancer develops from germ cells, which are precursors to egg cells, or from hormone-producing granulosa cells, rather than epithelial cells.

Early-stage ovarian cancer typically presents no noticeable symptoms. As it progresses, signs and symptoms may include pelvic or lower abdominal pain or heaviness, bloating, feeling full quickly when eating, back pain, vaginal bleeding between periods or after menopause, or changes in urinary or bowel habits. However, these symptoms can be indicative of various other conditions, and their presence does not necessarily mean a woman has ovarian cancer.

In some cases, cancerous tumors can invade surrounding tissues and spread to other areas of the body. Metastatic ovarian cancer commonly appears in the abdominal cavity or on the surfaces of nearby organs, such as the bladder or colon. Tumors that spread from their original site to other areas are termed metastatic cancers.

Some ovarian cancers exhibit familial clustering, termed hereditary ovarian cancers, which are linked to inherited gene mutations. These hereditary cases tend to develop earlier in life compared to non-inherited (sporadic) cases.

Ovarian cancer is often diagnosed at a late stage, making it challenging to treat. It results in approximately 14,000 deaths annually in the United States, exceeding any other gynecological cancer. However, early diagnosis and treatment significantly improve the 5-year survival rate.

Inheritance:

Most ovarian cancer cases are not caused by inherited genetic factors. These cancers are associated with somatic mutations acquired during a person's lifetime and do not cluster in families. A predisposition to cancer caused by a germline mutation is usually inherited in an autosomal dominant pattern, meaning that one copy of the altered gene in each cell is enough to increase a person's chance of developing cancer. Although ovarian cancer only affects women, the mutated gene can be inherited from either parent. Inheriting mutations in these genes means an increased likelihood of developing cancer, not the disease itself. Not all people who inherit mutations in these genes will develop cancer. In many cases of familial ovarian cancer, the genetic basis for the disease and the mechanism of inheritance are not yet fully understood.