Hereditary Cancers


 

Family history of ovarian cancer or breast cancer has long been known to be one of the strongest associations that would predict a future ovarian cancer.  If a woman has a mother or a sister with ovary cancer, then her risk for future development of the same ovary cancer is increased four times higher than the general population. Women who have inherited a gene mutation associated with hereditary cancer may have an elevated risk to develop cancer during their lifetime that is 2-30 times higher than the normal population.  An inherited cancer may often develop at a surprisingly early age. Ovarian cancer is caused by inherited mutations in 23% of cases. As of 2015 there were 16 genes known to be an inherited cause for ovarian cancer. STK 11 mutation was recently identified as a mutation with high risk for developing ovarian cancer, and is associated with a 42 increase in risk compared to the normal population A woman may inherit such a mutation from her father.  That means other family members with ovarian cancer may be several generations away from the patient found to carry a mutation. Inherited risk for ovarian cancer may occur in her family even though no ovarian cancer has existed. The men may exhibit prostate cancer, colon cancer, or breast cancer, and the women may also have had breast cancer, colon cancer or uterine cancer, but no ovarian cancer. Any woman with ovarian cancer is a candidate for genetic testing to find out if she is a carrier of a genetic mutation.

Multiple cancers in the same family may be explained by the same genetic mutation present in many members of the same family.  The BRCA gene was one of the first genes to be identified as a cause of hereditary cancer. Mutations of BRCA1 or of BRCA2 cause approximately three fourths of all the inherited ovary cancer cases.  Inherited cancer may be part of the Lynch syndrome. Lynch syndrome predisposes to multiple kinds of cancer and is the cause of 10-15% of hereditary ovarian cancers. An individual woman with a Lynch mutation has a 10-12% chance of developing ovarian cancer in her lifetime.  Multiple genes can cause the Lynch syndrome. Lynch syndrome is also a common cause for endometrial cancer. In men and women it is a common cause for early age cancer of the colon. A woman who carries a mutated Lynch gene has a significant lifetime risk for ovary cancer, endometrial cancer, colon cancer, stomach cancer, or kidney and bladder cancer.  Different patients in the same family may have any one of these but not all these cancers.

Most uterine cancers are not caused by inherited mutations, therefore universal genetic testing for uterine cancer patients is not currently recommended.  However, any patient with uterine cancer that occurs at age 45 or earlier is urged to have genetic testing because that early age occurrence increases the likelihood that the genetic predisposition because the cancer.  The majority of these patients have Lynch syndrome-related cancers. For women and Lynch syndrome families the uterine (endometrial) cancer will occur more often than colon cancer. This may be the first chance for genetic testing for the patient or her family.  Most of these young women will be cured from their uterine cancer. Their underlying risk for a life-threatening colon cancer remains and therefore great urgency to recognize their underlying risk and help complete testing that would prove Lynch carrier status. Any patient with Lynch syndrome mutation will be qualify for colonoscopy screening beginning at very early age and on a every 1 or 2-year schedule with the goal to identify colon cancer early in its existence and allowing patients to be cured.  If a woman with uterine cancer is confirmed to have a Lynch mutation, then all of her immediate family members including brothers can be tested prior to their developing a cancer, and this may save their life because men with Lynch syndrome often develop a colon cancer as their first cancer and it is often very advanced and not treatable at the time it is first diagnosed.

During a discussion for genetic counseling Dr. Martin wants to know about all the cancers in the family including those of the men and women. In our practice we spend a great deal of effort to identify these family cancer histories.  There are many cancers associated with this type of risk factor.

Most of the gene mutations associated with hereditary cancer represent genes that are supposed to protect our genetic DNA.  These genes do the job of preventing errors from being incorporated into DNA. Whenever your body makes a new cell it also must make a new copy of the DNA.  If errors are accumulated in the DNA, then genes cannot control the body function properly. Many of the genetic errors eventually lead to development of cancer. BRCA is an example of a tumor suppressor gene.  This type of gene fixes DNA. When a protector gene is abnormal then it cannot do its job and many other abnormalities develop as your body makes new cells over the many years of life. The body will eventually lose control of making new cells when too many errors are accumulated in the DNA.  A tumor will develop when new cells reproduce themselves at an accelerated rate and eventually they develop the ability to spread throughout the body and become a cancer.

A person born with a mutated suppressor gene, has inherited a defect in protection of the DNA, and that person begins accumulating problems in the DNA starting early in life.  The result is the person will often develop cancer at an early age. Dr. Martin places a high priority on identification of patients with inherited mutations prior to when they develop a cancer.  Cancer can often be prevented if patients who carry a mutation can be identified at a young age. Women carrying these mutations are often provided surgery that will prevent cancer. Dr. Martin is a strong proponent cancer prevention using these techniques referred to as risk reducing surgery.  This is often applied to prevention of uterine cancer, ovarian cancer, or breast cancer. It is particularly helpful that removing ovaries and creating early menopause can reduce the risk of future breast cancer by more than 50%. Many of these patients with inherited risk for cancer uterus or ovaries may also have an inherited risk for breast cancer.  By virtue of the risk reducing surgery pelvis they may also gain considerable protection against breast cancer.

Location
Knoxville Gynecologic Cancer Specialists
10810 Parkside Drive, Suite 200
Knoxville, TN 37934
Phone: 865-413-1867
Fax: (865) 218-6001
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865-413-1867