Genetic Testing & Colon Cancer
The Division of Colon and Rectal Surgery at Staten Island University Hospital offers genetic counseling services to individuals who may be at risk for an inherited cancer syndrome based on their personal and/or family history of cancer. Our experts provide personalized risk assessments, education and the opportunity for genetic testing when appropriate.
Sporadic vs. Hereditary Cancer
- Sporadic Cancer:
- Most cancers develop due to genetic damage we sustain over a lifetime. When genes acquire defects that impact the cells ability to grow and divide properly tumors form. Cancers that occur due to genetic changes we acquire over time are considered to be sporadic. Approximately 70-80% of all cancer is considered to be sporadic.
- Family Clusters of Cancer:
- Cancer that occurs in families more often than what would be expected by chance is considered a familial cancer cluster. Familial clusters have been reported for many types of cancer and are believed to be due to a combination of risk factors which include inherited susceptibility, environmental factors and chance.
- Cancer that results form genetic changes that are passed on from one generation to the next is considered hereditary. Approximately 5 - 10% of all cancers fall into this category.
Genes Associated with Increased Risk for Colon Cancer
A number of genetic defects have been found to be associated with hereditary colon cancer. These inherited genetic changes can result in an increased risk for developing colon cancer as well as other cancers in an individual's lifetime. Lynch syndrome and Familial Adenomatous polyposis (FAP) are two examples of inherited syndromes that are known to be associated with and increased risk for developing colon cancer.
- Lynch Syndrome
- The most common inherited form of colorectal cancer is hereditary non-polyposis colon cancer (HNPCC), also know as Lynch syndrome. It is estimated that 2-5% of all colorectal cancer cases are due to Lynch syndrome.
- Lynch syndrome predisposes an individual to colorectal cancer and other malignancies such as uterine, ovarian, stomach, urinary tract, small bowel, bile ducts, sebaceous skin tumors and brain tumors. Individuals that inherit a gene known to be associated with Lynch syndrome have a lifetime risk of up to 80% for colorectal cancer and a 20-60% risk of uterine cancer.
Familial Adenomatous Polyposis
- Familial adenomatous polyposis (FAP) is an inherited condition in which several polyps form in the colon. While these polyps start out benign, malignant transformation into colon cancer occurs in nearly 100% of affected individuals if not treated.
In addition to colon cancer, individuals with FAP may also be at an increased risk for developing other cancers such as that of the duodenum and stomach. Other non-cancerous findings known to associated with FAP include: pigmented lesions of the retina (CHRPE- congenital hypertrophy of the retinal pigment epithelium), jaw cysts, sebaceous cysts, and osteomas (benign bone tumors).
Having a risk assessment performed by a highly-skilled genetic counselor can help to determine if genetic testing is appropriate for you and/or your family members. Individuals that are found to carry a genetic change will work closely with their doctors to establish an appropriate screening and management plan to reduce risks for developing certain types of cancer and assist with early detection.
Deciding on Genetic Testing for Colon Cancer
Genetic testing should be considered for individuals at high-risk due to a personal and/or family history of cancer. You might fall into this high-risk category if:
- You or a close relative developed colon cancer before age 50
- You or a close relative have 10 or more cumulative colon polyps of any histology
- You have 3 or more close relatives on the same side of the family with uterine, ovarian, stomach, urinary tract, small bowel, bile ducts, sebaceous skin tumors or brain tumors (one or more diagnosed before age 50).
- You have the above mentioned cancers in more than one successive generation in your family
- You have a relative that has a known alteration in a gene associated with hereditary colon cancer
The Genetic Counseling Process
If you are considering genetic testing due to a personal and/or family history of cancer you may have many complex questions and concerns you would like to discuss prior to moving forward. A genetic counselor specializing in cancer genetics can meet with you to address your concerns and determine whether your family history suggests the presence of a hereditary cancer syndrome.
The genetic counselor will collect a detailed cancer-focused personal and family history. Using this information the counselor will work with you to:
- Assess your risk for developing cancer
- Discuss the option of genetic testing when appropriate
- Review the risks, benefits and limitations of genetic testing including:
- Accuracy of the test
- Implications of test results
- The turn-around time for results
- Financial aspects of the testing
- Concerns regarding genetic discrimination
- Provide you with educational materials and emotional support
To make an appointment or for more information on cancer genetic counseling, please contact us at 718-226-6230