Ovarian cysts are small fluid-filled sacs. During ovulation, the ovary releases a follicle, which consists of the egg surrounded by a fluid and cells that produce the fluid. Sometimes the cells in the follicle produce excessive amounts of fluid or the fluid builds up in the ovary. A cyst forms when the fluid accumulates and enlarges the follicle beyond its normal size. Cysts may also form in the corpus luteum, a glandular mass formed by the follicle that produces progesterone to prepare the uterine lining for implantation of a fertilized egg. Corpus luteum cysts form in much the same way as follicular cysts, with cells overproducing fluid. Cysts may also form in other types of ovarian cells, although those types of cysts are uncommon.
In contrast, ovarian cancer most often develops from the cells on the surface of the ovary, or the epithelial cells. The DNA of these cells becomes damaged and the cells grow too quickly, divide too often, and fail to die off. The cells continue growing and reproducing more damaged cells, eventually forming a mass, or tumor. The cancerous cells may also migrate, or metastasize, to surrounding tissues. Ovarian cancer may also develop in the germ cells, or those that produce the eggs, or connective tissue cells, called stromal cells.
Neither ovarian cysts nor cancer produce distinct symptoms. Ovarian cysts rarely cause symptoms, although some women may feel abdominal pressure, heaviness, or aching. Occasionally a cyst will cause a sharp, stabbing pain the abdomen if it ruptures. Some cysts produce hormones that may cause irregular or heavier than normal periods.
Ovarian cancer rarely causes symptoms in the early stages. Early symptoms are vague, such as abdominal discomfort that is often mistaken for indigestion, bloating, gas pains, or a backache. The tumor causes more symptoms as it grows and spreads. Symptoms of more advanced ovarian cancer include abdominal swelling, pelvic pain, anemia, and weight loss. Some ovarian cancers produce estrogens that enlarge breasts and cause the uterine lining to thicken. Others produce androgens, or male hormones, that may cause body hair growth.
An ultrasound may distinguish cysts from cancerous tumors, but it is inexact. If there is any doubt whether a growth is benign or malignant, the growth is removed and biopsied. The treatment for ovarian cysts vs. cancer is vastly different. Ovarian cysts usually resolve without treatment and most disappear within one to two months. Cysts that linger may be removed by laparoscopy. Nearly all cysts are benign, and it is very rare for a cyst to become cancerous.
The first step in treating ovarian cancer is surgical removal of the ovaries, fallopian tubes, and uterus. If the cancer has metastasized to neighboring tissue, that is removed as well. In early stage ovarian cancer, the surgeon may remove only the affected ovary. Surgery is followed by chemotherapy. Radiation is rarely used. When diagnosed in later stages, ovarian cancer has a high rate of recurrence.
William H. Parker, MD: A Gynecologist’s Second Opinion: If You Have Ovarian Cysts https://www.gynsecondopinion.com/ovarian-cysts.htm
William H. Parker, MD: A Gynecologist’s Second Opinion: Ovarian Cancer and the Search for Early Detection https://www.gynsecondopinion.com/ovarian-cancer.htm
Merck Manual: Ovarian Cancer https://www.merckmanuals.com/home/sec22/ch252/ch252c.html
MayoClinic.com: Ovarian Cancer Causes https://www.mayoclinic.com/health/ovarian-cancer/DS00293/DSECTION=causes