Hereditary Cancer Syndromes
Within the past several yearsí research has identified specific genes that can potentially cause the development of cancer. When these genes pass through a family, the cancer has a chance of showing up in several members of that family. Due to the discovery of inherited patterns, genetics counseling is now available to assist with risk assessment and genetic testing. Approximately 5-10% of all cancers may be an inherited pattern with a mutation of a gene that is carried by members of a family. If a mutation of the gene is inherited then members of the family may be at increased risk for developing specific types of cancers in their lifetime.
Hereditary breast and ovarian cancer
Approximately 10% of breast and ovarian caners are hereditary with one in eight women developing breast cancer and one in seventy developing ovarian cancer in their lifetime. Researchers have identified the BRCA1 and BRCA2 genes that work in cell growth, cell division and damage repair to the DNA. When a mutation occurs, cell damage may not be repaired, which may lead to the development of cancer. Mutations have been identified more commonly in certain ethnic groups such as the Ashkenazi Jews (Eastern European Jews), in which an estimated 40% of the group carries at least one of three types of mutations that can cause breast and ovarian cancer. Also, ethnic groups from Iceland, Denmark and French Canada have a higher risk. In many centers in the US, genetic testing is offered to women who have one of these cancers. Blood or saliva testing can be done to test for the mutations. Women who have test positive for the mutations in the BRCA genes have a 50-85% of developing breast cancer by age 70 and a 40-60% risk of developing ovarian cancer. It also can indicate that after a woman has one episode of breast cancer and has a positive mutation test, she will be at a higher risk for a recurrence of the disease or a second breast cancer developing within ten years. Men who carry a mutation of the BRCA genes are at higher risk of developing breast cancer and prostate cancer. Women diagnosed with a mutation of the BRCA genes are recommended to do mammograms, breast exams and self breast checks starting by age 25 and get pelvic exams, ultrasound of the ovaries, and CA125 testing regularly.
Lynch syndrome (Hereditary non-polyposis colorectal cancer syndrome)
Lynch syndrome is characterized by early age onset of colon cancer and can also increase the risk of endometrial and ovarian cancer in women. It can also include cancers of the stomach, pancreas, urethra, and certain brain tumors. Colon cancer is the third most common cancer in both men and women and occurs in one in seventeen adults. Usually families with Lynch syndrome have three or more closely related members with colon cancer, in one or more generations, and at least one person diagnosed prior to age 50. Genetic testing has been developed to assist in the diagnosis of gene mutations that may lead to Lynch syndrome.
Cowden syndrome is a rare inherited pattern that can increase the risk of cancers of the breast, thyroid, endometrium and colon. Itís usually associated with lesions on the skin especially of the face, mouth, and extremities. During a personís lifetime, there is a 10% risk of thyroid cancer and a 25-50% risk of breast cancer. A person with Cowden syndrome has a fifty percent chance of passing it on to their children. The genetic testing available is PTEN. If the test is positive, a yearly thyroid ultrasound should be started at age 18 and clinical breast exams and mammograms should be started by age 30.
A rare syndrome associated with a mutation in the tumor suppressor gene. The family members with mutations are at high risk for sarcomas of the breast, brain, and adrenal glands. Those with this gene mutation have a risk of 50% chance of developing cancer by age 30 and 90% by age 60.
Von Hippel-Lindau syndrome (VHL)
Von Hippel-Lindau syndrome is a rare disorder produced by mutations in the VHL with as high as 50% of children inherited the disorder. It is associated with cysts and cancers of the kidney, pancreas, spinal cord, brain, inner ear and retina. Evaluation should be considered if any member of a family has been diagnosed with VHL.
Peutz-Jeghers syndrome (PJS)
PJS is a syndrome produced by a mutation in the STK11 gene leading to hamartomatous polyps of the intestinal tract. It carries increased risk of cancers of the breast, ovaries, cervix, pancreas, stomach and colon.
NF-1 is a condition associated with skin neurofibromas and malignant nerve tumors of the skin. It has also carried a five fold increase in breast cancer for individuals diagnosed with the syndrome.
If you have questions about any of the syndromes and cancers mentioned, discuss your concerns with your physician. Genetic counselors are available in most cities.