The risk for breast cancer and many other forms of cancer is increased with Li-Fraumeni syndrome (LFS), a genetic autosomal dominant cancer syndrome. A diagnosis of LFS is made when all of the following characteristics are present in a family:
Sarcoma at less than 45 years of age and
A first-degree relative, such as parent, sibling, or child, with cancer at less than 45 years of age and
A first- or second-degree relative (aunt, uncle, or grandparent) with cancer at less than 45 years of age or sarcoma at any age
The majority of LFS (about 70 percent) is caused by mutations in a gene on chromosome 17 known as p53. Mutations in p53 confer an increased risk for early onset breast cancer, childhood sarcoma, osteosarcoma, brain tumors, leukemia, and adrenocortical carcinoma.
People with a p53 mutation have a 50 percent chance of developing one of the associated cancers by age 40 and a 90 percent chance of developing cancer by age 60. Breast cancer appears to be the greatest risk for women, but less than 1 percent of all breast cancer is thought to be related to LFS. For those affected by LFS, breast cancers generally occur in premenopausal women.
The p53 gene is a tumor suppressor gene, which usually controls cell growth and cell death. Both copies of a tumor suppressor gene must be altered, or mutated, before a person will develop cancer. With LFS, the first mutation is inherited from either the mother or the father and is therefore present in all cells of the body. This is called a germline mutation. Whether a person who has a germline mutation will develop cancer and where the cancer(s) will develop depends on where (which cell type) the second mutation occurs. For example, if the second mutation is in the breast, then breast cancer may develop. If it is in the bone, then osteosarcoma may develop. The process of tumor development actually requires mutations in multiple growth control genes. Loss of both copies of p53 is just the first step in the process. What causes these additional mutations is unknown. Possible causes include chemical, physical, or biological environmental exposures or chance errors in cell replication.
Some individuals who have inherited a germline p53 mutation never develop cancer because they never get the second mutation necessary to knock out the function of the gene and start the process of tumor formation. This can make the cancer appear to skip generations in a family, when, in reality, the mutation is present. People with a mutation, regardless of whether they develop cancer, however, have a 50/50 chance to pass the mutation on to the next generation.
It is also important to remember that the p53 gene is not located on the sex chromosomes. Therefore, mutations can be inherited from the mother's or the father's side of the family.
Do You Need To Be Tested?
You should consider testing for Li-Fraumeni syndrome if:
- You had breast cancer under age 30
- ou have had an adrenocortical carcinoma or choroid plexus carcinoma
- You have had two or more cancers, with at least one before age 36
- You and your family have multiple cancer diagnoses before age 45
- You have a personal/family history of rare and/or early onset cancers
What Is The Testing Process?
The genetic counselor will assess your personal and family history to see if you are a candidate for Li-Fraumeni syndrome testing. If you are, a blood test can show if you have a p53 mutation. The blood test may take several weeks.
Why Would I Want To Know?
Knowledge of a gene mutation in your family is very helpful for doctors when screening, diagnosing, and treating patients for cancer. Since Li-Fraumeni syndrome is passed down by family members, we can identify people at high risk to develop cancer and provide them with early detection and treatment options.
Some people do not want to know if they have Li-Fraumeni syndrome. Because there are multiple risks for cancers, doctors still do not know the best way to care for these patients or how to detect these cancers early. Deciding to do genetic testing is a personal decision that a genetic counselor can help you learn more about.
How Can I Learn More About This?
Ask your doctor if you’re at risk for Li-Fraumeni syndrome or call 1.800.4BAYLOR to learn more about the genetic counseling process.