What is ovarian cancer?
Ovarian cancer starts in the cells of the ovary. A cancerous (malignant) tumour is a group of cells that can grow into and destroy nearby tissue. It can also spread (metastasize) to other parts of the body. Cancerous ovarian tumours are grouped by the type of cells that the cancer starts in.
Epithelial ovarian carcinoma starts in epithelial cells. It is the most common type of ovarian cancer. Serous carcinoma is the most common type of epithelial ovarian carcinoma.
Many serous ovarian carcinomas are now thought to come from cells from the nearby fallopian tube that have implanted on the surface of the ovary.
Tumours of borderline malignancy also start in the epithelial cells. They share some, but not all features of carcinomas under the microscope. They do not usually spread into nearby tissues or other parts of the body. Examples of tumours of borderline malignancy are serous tumours and mucinous tumours.
Stromal tumours start from stromal cells. Granulosa cell tumours are the most common type of stromal tumour that can be malignant.
Germ cell tumours start in germ cells. Mature cystic teratoma (dermoid cyst) is the most common type of ovarian tumour overall. It is usually non-cancerous. The most common type of cancerous germ cell tumour is dysgerminoma.
Primary peritoneal serous carcinoma can develop in the peritoneum, which is the membrane that lines the walls of the abdomen and pelvis. It is similar to epithelial ovarian cancer, but there is very little or no cancer in the ovary and it isn’t clear where the cancer started.
Changes to cells in the ovary don’t always lead to cancer. Changes to the cells may lead to non-cancerous conditions such as cysts. They can also lead to non-cancerous tumours such as an adenofibroma.
The ovaries have 2 main functions. They make the female sex hormones and they produce mature eggs.
The female sex hormones are estrogen and progesterone. The ovaries are the main source of these hormones.
Estrogen is the main female sex hormone. It is responsible for the development of a woman’s breasts, body shape and reproductive organs.
Progesterone prepares the body for conception by causing the buildup of the uterine lining (endometrium) and regulates menstruation and pregnancy.
Each month during ovulation, an ovary releases a mature egg. The egg travels down the fallopian tube to the uterus. If it is fertilized by a sperm, the egg attaches itself (implants) to the lining of the uterus and begins to develop into a fetus. If the egg is not fertilized, it is shed from the body along with the lining of the uterus during menstruation.
During menopause, the ovaries stop releasing eggs and producing sex hormones.
American Cancer Society. Ovarian Cancer. 2014: http://www.cancer.org/acs/groups/cid/documents/webcontent/003130-pdf.pdf.
American Society of Clinical Oncology. Ovarian, Fallopian Tube, and Peritoneal Cancer. 2016: http://www.cancer.net/cancer-types/ovarian-cancer/view-all.
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