PUBLISHED: 5th June 2025
The NF1 gene is a tumor suppressor gene that produces a protein called neurofibromin, which helps regulate cell growth and division.
What is an NF1 mutation?
Inherited mutations in the NF1 gene cause a condition known as neurofibromatosis type 1 (NF1) or von Recklinghausen syndrome. NF1 is the most common form of neurofibromatosis, a medical condition that causes noncancerous growths along the nerves.
A person can get NF1 in one of two ways. Half of the people who have a mutation in NF1 inherited it from one of their parents. The other half have a new or de novo mutation, which happens at conception or soon after. They are the first in their family to develop the mutation.
What are the main cancer risks for people with an NF1 mutation?
People with NF1 mutations have increased risks for cancer, as well as noncancerous or benign growths called neurofibromas, and other medical issues.
The main cancer risks for people with NF1 mutations are early-onset breast cancer (before age 50) and a type of cancer of the nerves known as malignant peripheral nerve sheath tumors (MPNST). MPNSTs are a type of sarcoma that develops in the protective lining of nerves. They grow quickly and can spread to other areas.
| Cancer type | Lifetime risk with a NF1 mutation | Lifetime risk for general population |
| Early onset breast cancer (before age 50) | 20-40% | 12.5% |
| MPNST | 8-13% | Less than 1% |
What are the other cancers risks for people with an NF1 mutation?
People with NF1 mutations are at increased risk of other types of tumors that may be benign or cancerous, including:
| Tumor type | Notes |
| Gastrointestinal stromal tumors (GIST) | GIST develops in the digestive system, most often in the stomach and small intestine. |
| Glioma | Gliomas are a type of tumor of the brain or spinal cord. Low grade gliomas are the most common type in people with NF1 mutations. They are usually slow growing and benign, however, adults with NF1 can also develop cancerous gliomas. |
| Pancreatic neuroendocrine tumors (PNETs) | PNETs are rare tumors that form in the cells that make hormones that are necessary to control blood sugar and other metabolic functions. They may also be called islet cell tumors. |
| Pheochromocytoma | PNETs are rare tumors that form in the cells that make hormones that are necessary to control blood sugar and other metabolic functions. They may also be called islet cell tumors. They can cause high blood pressure, anxiety, headache, sweating and rapid heartbeat. |
More research is needed to understand the lifetime risks for these cancers in people with NF1 mutations.
What can people with an NF1 mutation do?
Expert guidelines provide recommendations for screening for these cancers.
People with an inherited NF1 mutation who have been diagnosed with cancer may also qualify for specific treatments or clinical trials.
Having an NF1 mutation also increases the risk for other medical concerns, many of which begin in early childhood. Expert guidelines are available for managing these conditions.
Cancer risk management for people with NF1 mutations
People with NF1 mutations have options for managing their increased cancer risk. Expert guidelines are available to help them manage their cancer risk.
If you have an NF1 mutation, we recommend that you speak with a genetics expert who can look at your personal and family history of cancer and help you decide on a plan for managing your risk.
Experts recommend that all people with an inherited NF1 mutation receive education on the signs and symptoms of NF1-related cancers. NCCN guidelines for breast cancer and the American College of Medical Genetics and Genomics are summarized below.
Breast cancer risk management
| Beginning age | Recommendation | Additional Information |
| 25 | Learn to be aware of changes in your breasts | Based on NCCN guidelines for women of average risk |
| 25 | Breast exam by doctor every 1-3 years | Based on NCCN guidelines for women of average risk |
| 30 (or earlier based on family history of breast cancer) | Yearly mammogram | |
| 30-50 | Consider breast MRI with and without contrast | |
| >50 | Yearly mammogram | Based on NCCN guidelines for women of average risk |
More research is needed to show whether people with NF1 mutations benefit from risk-reducing mastectomy. Talk with your doctor about the option of risk-reducing mastectomy, based on your personal and family history of cancer.
Malignant peripheral nerve sheath tumors (MPNST) risk management
- Learn to be aware of the signs of MPNST and immediately report any symptoms to your doctor.
- Consider referral to specialized clinics that see numerous patients with MPNST.
- MRI should be considered over CT scanning to reduce exposure to radiation.
Breast cancer treatment
Breast cancers in women with NF1 mutations are more likely to be hormone receptor-negative (HR-negative). This means they don’t respond to hormonal therapies that can effectively treat other types of breast cancer.
Breast cancers in women with NF1 mutations are often HER2-positive. HER2 is a protein that is sometimes found on the surface of breast cancer cells. Some breast cancer drugs work by targeting HER2 to block or slow cancer growth. HER2-positive breast cancers may respond to a type of targeted therapy called anti-HER2 therapy.
Other medical issues
NF1 is often diagnosed in childhood. Symptoms develop at birth or shortly afterward, and almost always by age 10. Symptoms tend to be mild to moderate, but may vary from person to person.
Some of the most common symptoms of NF1 include:
| Condition | Details |
| Café-au-lait spots | These light brown spots on the skin are common in many people. Having more than six cafe au lait spots suggests an NF1 mutation. |
| Freckles | Freckles are common, but groups of freckles in unusual places, like the underarm or groin may indicate an NF1 mutation. |
| Cutaneous neurofibromas | Neurofibromas are small, non-cancerous tumors that grow from nerve cells. Cutaneous neurofibromas are the most common type of neurofibroma in people with an NF1 mutation. They appear as soft bumps in or under the skin. |
| Plexiform neurofibromas | Plexiform neurofibromas are another type of neurofibroma. These non-cancerous tumors are different than cutaneous neurofibromas because they can grow to be quite large and may cause pain, disfigurement or other physical issues. • Koselugo (selumetinib) is the first FDA-approved therapy for children and teens to shrink plexiform neurofibromas that cannot be completely removed by surgery. It is taken orally once a day. • Find more information about Koselugo here. |
| Lisch nodules | These are tiny bumps on the iris, which is the colored part of the eye. They usually do not affect a person’s vision. |
| Bone problems | These may appear as a curved spine (scoliosis) or a bowed lower leg. |
| Learning disabilities | It is common for children with an NF1 mutation to have some trouble with learning. Attention-deficit/hyperactivity disorder (ADHD) and speech delay are also common. |
Ask your doctor
If you or a family member has an NF1 mutation, consider asking your doctor the following:
- What symptoms should I watch for?
- What is my risk of developing cancerous (versus benign) tumors?
- Are there new treatments or clinical trials I should know about?