Ovary – Tissue and Systems

This article describes the basic anatomy and function of the ovaries.  By understanding the basic form and physiology of the ovaries, the symptoms of ovarian cancer may be better understood.

The ovaries are pelvic female organs that are involved in the reproductive cycle.  Each ovary houses ovum or eggs that have the potential to become a fertilized zygote and develop to a future child.  Ovaries serve dual function both in future child-bearing and as hormone secreting glands.  There are normally two ovaries, one on each size of the uterus.  The uterus is shaped roughly like an upside-down pear.  The top of the pear has two arms that arm called fallopian tubes.  These serve as a conduit for a ruptured ovum to travel to the inner lining of the uterus for possible implantation and growth.  The ovaries are suspended by ligaments.  The ovary has the ability to secrete sex hormones such as estrogen and progesterone.  These hormones normally rise and fall throughout the menstrual cycle.  If an embryo implants, the ratio of hormones changes and progesterone helps maintain the pregnancy.

The size of the ovary varies throughout the menstrual cycle and menopausal status.  The average ovary is about 3 cm but this may increase to 6 cm with development of a follicular cyst.  The ovaries have no direct sensory nerves like the skin, but distention or infection will cause ache or pressure in the pelvis.  The artery that supplies the ovary runs near the ureters which are the drainage tube of the kidney that transports urine to the bladder.

The ovaries can have a number of diseases and disorders in addition to cancer.  Large cysts or tumors can grow on the ovary that is not cancer.  The difference between a non-cancer and cancer tumor is that a cancer has abnormal cells that try to invade into other areas of the body.  A growth that is not cancer will swell and cause pressure on adjacent structures but will not invade beyond its normal boundaries despite being much larger than it should be.

Ovarian cancer is the 8th most common cancer diagnosed in women and the 5th most common cause of death from cancer in women, in the United States.  Ovarian cancer is the second most common cancer diagnosed in the female genital tract, behind cervical cancer.  Ovarian cancer is the most common cause of death from a gynecologic tumor.

The real challenge with ovarian cancer stems from the lack of symptoms and difficulty in early detection.  This is analogous to a tumor in the tail of the pancreas that grows and spreads before there is a chance to detect it.  Some cancers display early signs and are easier to spot.  For example, a woman may feel a breast tumor and be prompted to see a doctor for a possible breast cancer.  A young man may feel a lump on his thyroid gland and be prompted to get evaluated for a possible thyroid cancer.  There is no practical way to “feel” your ovary.  A tumor of the ovary often has no symptoms.  This allows growth and spread of the cancer cells without treatment.  Ovarian cancer is more common in older women, and when diagnosed in a woman older than 65 years old it is almost always far advanced in stage.  The most common age for diagnosis with ovarian cancer is around 60 but can be diagnosed rarely in the 30’s or much later in life in the 80’s.

The best way to detect ovarian cancer might be to focus screening on who is at high risk for it.  This same strategy is used to help detect colon cancer in high risk families.  The difficulty with this becomes the lack of readily identifiable risk factors.  Some common factors that are thought to be risks for ovarian cancer are:

  • Older age
  • Fatty diet
  • Relatives with ovarian cancer
  • Difficulty with pregnancy / infertility
  • Lack of children (i.e. nulliparity)
  • Abnormal ovulation history

Interestingly, these are similar risk factors that have been identified with risk for breast cancer as well.  It may be that exposure to higher amounts of estrogen plays a role.  There are some genetic factors that are known to play a role.  A gene that is passed along in certain families is known as the BRCA gene.  Women with this gene develop breast cancer at an early age and are also at a high risk for development of breast cancer.  If a woman has relatives who develop either breast cancer and/or ovarian cancer at an early age, it may be wise to have testing done for this gene.  Once a woman is proven to have this gene, the often undergo prophylactic (or preventative) treatments to help prevent a future cancer such as having both ovaries removed and/or having the breasts removed.

There are several different types of ovarian cancers that are derived from the different cell types within them.  There is a blood test known as CA-125 which is also a tumor marker for ovarian cancer.  The problem with this test is that it is elevated with many other conditions that are not cancer.  It lacks specificity to be a true screening test for ovarian cancer.  The health of the ovaries can be assessed with physical examination and imaging of the ovaries.  The easiest way to image the ovaries is with an ultrasound.  If there is a suspicion of cancer, formal staging with CT scan and surgery is often needed.

REFERENCES:

  1. www.cancer.gov/cancertopics/types/ovarian
  2. www.healthfinder.gov/news/newsstory.aspx?docID=656097
  3. Townsend Jr, CM; Beauchamp RD; Evers BM; Mattox KL. (2008) Townsend: Sabiston Textbook of Surgery, 18th ed.  Chapter75 .  New York, NY: Saunders.
  4. Katz VL, Lentz GM, Lobo RA, et al. (2007) Katz: Comprehensive Gynecology, 5th ed. Chapter 33.  Philadelphia, PA : Mosby-Elsevier
  5. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.