What is Colorectal Cancer?
Colorectal cancer is also called colon cancer or rectal cancer. It refers to any cancer in the colon from the beginning (cecum) to the end (rectum). Colorectal cancer occurs when cells that line the colon (large bowel or intestine) or the rectum become abnormal and grow out of control. Polyps are usually benign growths that protrude from a mucus membrane. They can form in the colon and rectum. These polyps are adenomatous polyps and may eventually progress into cancer if left untreated.
 | | Figure 2. Location of the colon in the body with corresponding cut-away section of a colon segment with polyps. |
There are a number of different inherited conditions that have a significant risk of colon cancer. Research into these conditions, along with the knowledge that researchers have gained, have led to the development of screening and management guidelines for both patients and their families. Compliance with these guidelines may prevent cancer and other complications associated with these diseases. Most colorectal cancer is sporadic, implying no prior family history of the disease. Individuals with a family history of colorectal cancer are described as having familial or hereditary colorectal cancer.
 | | Figure 3. Distribution of colorectal cancers |
What is Familial Colorectal Cancer?
The occurrence of colorectal cancer in more than one family member may be due to chance alone. However, it could also mean the potential for developing colorectal cancer has been passed from one generation to the next but the exact gene has not been identified. Relatives of a person with colorectal cancer may be more likely to develop it.
It is estimated that 15–50% of colorectal cancers are familial. A single gene, a combination of genes, or a combination of genetic and environmental factors can contribute to familial colorectal cancer. Typically these families have one or two members with a history of colorectal cancer or pre-cancerous polyps.
What is Hereditary Colorectal Cancer?
A family has hereditary colorectal cancer when the exact gene that causes the disease is known. Several genes that cause hereditary colorectal cancer have been identified. There may be other genes that have not yet been discovered.
If more than one person in a family has colorectal cancer, it could mean that the potential for developing this form of cancer has been passed from one generation to the next. In these families, relatives of people with colorectal cancer may be much more likely to develop it. Inherited colorectal cancers are associated with a genetic mutation in a cancer susceptibility gene. Everyone inherits one susceptibility gene from each parent. If a mutation in one copy of a cancer susceptibility gene is passed from the parent to child, the child is predisposed to develop cancer. The genetic causes of two hereditary colorectal cancer syndromes, familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC) have been identified.
What is FAP (Familial Adenomatous Polyposis)?
Familial adenomatous polyposis is an inherited condition caused by a mutation on chromosome 5. FAP is characterized by hundreds to thousands of polyps in the gastrointestinal tract (primarily the colon and rectum). These polyps are at increased risk for malignancy. Polyps begin to appear during teen years and often become cancerous by age 40.
 | | Figure 5. A,Appearance of FAP inside of the colon;B,endoscopic image of polyps;C,enlargement of polyps in the colon. |
Polyps (abnormal mushroom-like growths) may vary in size from less than one tenth of an inch to 1–2 inches. They may be large enough to block part of the intestine. If patients with FAP are left untreated, one or more of these polyps may develop into cancer. FAP may also be associated with benign tumors of the skin, soft connective tissue, and bones. It is caused by a mutation in a gene called APC. In some people FAP may be inherited, whereas in others it is not (sporadic).
 | | Figure 6. Illustrative comparison of polyp size. |
What is Attenuated FAP?
Some families are affected with attenuated FAP (AFAP). This is a mild (or attenuated) form of FAP in which affected individuals develop fewer polyps at a later age than those with typical FAP. Although people with AFAP tend to develop colon cancer at a later age than individuals with typical FAP, they still have a near 100% lifetime risk of colon cancer. If AFAP is suspected within a family, it is important that family members be screened with colonoscopy rather than flexible sigmoidoscopy because polyps are not evenly distributed throughout the colon. Because the number of polyps and age of onset can vary greatly from one family member to another in a family with AFAP, screening should begin at age 11.
How is FAP inherited?
People with FAP have a 50% chance of passing the condition to each of their children. The condition can be passed on even if the patient has had his or her own colon removed. Children who do not inherit the condition from their parent cannot pass it to their own children. About one third of people with FAP do not have an affected parent. An individual who is the first in the family to have the condition has a new or spontaneous mutation. Individuals with new mutations can pass FAP to their children.
(1) George has FAP, his wife Susan is unaffected. They have 3 children, George, Jr., Stephen, and Carol. All were at 50% risk of developing FAP. George, Jr., and Carol are affected. (2) George, Jr. and his wife Connie have 2 children. Both children had a 50% chance of inheriting FAP. Their daughter Alice is affected. (3) Stephen and his wife Gloria have 2 children. Because Stephen is unaffected, there was no risk to his children of developing FAP. (4) Carol and Bill have 3 children. Each child had a 50% chance of inheriting FAP and two are affected; son Billy is not. Genetic counseling is available and recommended for individuals with FAP and for their family members. Genetic counselors will explain the inheritance pattern of FAP, discuss which family members are at risk for developing the condition, and provide necessary information regarding genetic testing. Counseling services are available through genetic and oncology departments in many hospitals. To make an appointment with a member of the Johns Hopkins professional medical team or to speak with someone at the Colorectal Cancer Risk Assessment Service, please call (410) 614-LIFE (5433). Also, it is recommended that FAP families contact registries for access to resources and for help with identification of family members at risk.
Symptoms
Many patients with colorectal cancer experience no symptoms in the early stage of their disease. In fact, many people have no symptoms until the disease is quite advanced. Therefore, routine colorectal screening and an appreciation of risk factors are extremely important. Since many of the symptoms of colorectal cancer are also symptoms of a variety of other colon diseases, it is important to see your physician so that the necessary tests can be run and a diagnosis made. The following is a list of symptoms that may occur: Blood in the stool
Diarrhea that is not the result of diet or illness
A long period of constipation
Crampy pain in the abdomen
Change in bowel habits
Persistent decrease in the size or caliber of stool
Frequent feeling of distention in the abdomen or bowel region(gas pain, bloating, fullness, with or without cramping)
Weight loss with no known reason
Vomiting and continual lack of energy In addition to polyps, abnormalities in other areas of the body may give early clues to the presence of FAP. These abnormalities may include bumps or lumps on the bones of the legs, arms, skull, and jaw; cysts of the skin; teeth that do not erupt when they should; and freckle-like spots on the inside lining of the eyes. It should be emphasized that there is no safety in simply waiting for symptoms to develop. It is vital that parents and guardians make every effort to have examinations of their children starting at age 11 even if they do not have symptoms.
Resources American Cancer Society
The American Cancer Society
National Headquarters
1599 Clifton Road, N.E.
Atlanta, Georgia 30329
800-ACS-2345
http://www.cancer.org/ The ACS can offer assistance if cancer should occur. Check the telephone directory for your local chapter. State Vocational Rehabilitation Service
This service offers training for another vocation if one should be physically unable to return to the same kind of work performed before the surgery. Check your telephone directory for your state services. Generation to Generation
This newsletter is for people concerned about hereditary colon cancer and polyposis. It is free to all individuals with these conditions and their families and features articles on new research, the genetics of cancer, treatment, and quality of life, among many other topics. The editors welcome suggestions, questions, and personal stories from readers. This publication may be obtained by contacting Editor, Generation to Generation, Dept. of Behavioral Science, Box 243, M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030. Polyposis and Hereditary Colorectal Cancer Registries
Registries may be contacted for the names of experts in the management of FAP. Registries can also help to identify relatives at risk for the disorder. Further information concerning Polyposis Registries may be obtained by clicking here or contacting: Coordinator, Hereditary Colorectal Cancer Registry
The Johns Hopkins Hospital
550 North Broadway, Suite 108
Baltimore, MD 21250-2011
Phone: 1-888-77-COLON
Fax: 410-614-9544
E-mail: hccregistry@jhmi.edu Cancer Information Service (CIS)
Toll Free: 1-800-4-CANCER
The Cancer Information Service is a national toll-free telephone inquiry system that provides information about cancer and cancer-related resources to the general public, patients and their families, as well as health professionals. Most CIS offices are associated with Comprehensive Cancer Centers or community hospitals. CIS offices do not diagnose or recommend treatment for individuals. They provide support, understanding, and rapid access to the latest information, as well as referral to local services and resources. Printed materials may supplement telephone information. All calls are kept confidential, and individuals do not need to give their names. The National Society of Genetic Counselors, Inc. (NSGC)
The National Society of Genetic Counselors, Inc. (NSGC)
233 Canterbury Drive
Wallingford, PA 19086-6617
610-872-7608
www.nsgc.org The National Society of Genetic Counselors is the professional membership association for the genetic counseling profession. NSGC has developed a resource link to assist consumers in locating genetic counseling services.
Make an appointment today - call (410) 955-4166.
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