Nevoid Basal Cell Carcinoma Syndrome

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What is Nevoid Basal Cell Carcinoma Syndrome?

Nevoid Basal Cell Carcinoma Syndrome (NBCCS) is also known as Gorlin syndrome. NBCCS is a hereditary condition characterized by multiple basal cell skin cancers or basal cell nevus syndrome. Other common findings include jaw cysts, pits on the palms of the hands or soles of the feet, calcium deposits in soft tissues, and skeletal (bone) changes. The appearance of a person with NBCCS may include a larger head size, a prominent forehead, broad bridge of the nose, wide spaced eyes, skin cysts, and small skin bumps called milia. The jaw cysts and basal cell skin cancers usually develop in the first ten years of a person's life, but they may not appear until the teenage years or early adulthood. Children with NBCCS may have the appearance features described above, including pits on their hands and feet. There is a small (5%) chance for children with NBCCS to develop a type of brain cancer called medulloblastoma.

Multiple basal cell skin cancers and jaw cysts are the most common features of NBCCS and are present in about 90% of people who have the condition. There are several other features that have been associated with NBCCS. The number of features present and the severity of symptoms can vary among people with NBCCS, even within the same family. Black people with NBCCS may have jaw cysts as the primary feature of the disease and may develop far fewer sun-related basal cell skin cancers than people of other races with NBCCS.

What causes NBCCS?

NBCCS is a genetic condition. This means that the cancer risk and other features of NBCCS can be passed from generation to generation in a family. The major gene associated with NBCCS is called PTCH. A mutation (alteration) in the PTCH gene gives a person an increased risk of basal cell skin cancer and other symptoms of NBCCS. Research is ongoing to learn more about NBCCS and to identify other genes involved.

Sun exposure and radiation therapy (for instance, as a possible treatment for medulloblastoma) increase the number of basal cell skin cancers that a person with NBCCS develops. Some individuals have literally thousands of basal cell cancers in areas of skin that are exposed to the sun.

How is NBCCS inherited?

Normally, every cell has two copies of each gene: one inherited form the mother and one inherited from the father. NBCCS follows an autosomal dominant inheritance pattern, in which a mutation happens in only one copy of the gene. This means that a parent with a gene mutation may pass along a copy of the normal gene or a copy of the gene with the mutation. Therefore, a child who has a parent with a mutation has a 50% chance of inheriting that mutation. A brother, sister, or parent of a person who has a mutation also has up to a 50% chance of having the same mutation. It is also possible that the NBCCS in an individual was caused not by an inherited mutation but, rather, by a spontaneous gene mutation (see below).

How common is NBCCS?

It is estimated that about one in 40,000 people have NBCCS. As many as 30% of people with NBCCS do not have any family history of the condition. They have a de novo (new) mutation in the PTCH gene.

How is NBCCS diagnosed?

NBCCS is diagnosed when a person has at least two major features of NBCCS and one minor feature, or one major feature and at least three minor features.

Major Features:

Multiple basal cell skin cancers

Increased calcium deposits in the head (seen on an x-ray)

Jaw cyst(s)

Two or more pits on the palms of the hands or soles of the feet

A parent, sibling, or child with NBCCS

Minor Features:

Medulloblastoma in childhood

Increased head size

Cleft lip or palate

Abnormal shape of the ribs or spinal bones

Extra fingers or toes

Eye problems

Fibromas (benign fibrous tumors) of the ovaries or heart

Abdominal cysts

If a person has a family history of NBCCS, that person is also suspected of having NBCCS if they have jaw cysts, multiple basal cell skin cancers, pits on the palms of the hands or soles of the feet, or calcium deposits in the head. Genetic testing for mutations in the PTCH gene is available for people suspected to have NBCCS. A mutation in the PTCH gene is found in up to 85% of families diagnosed with NBCCS.

What are the estimated cancer risks associated with NBCCS?

People with NBCCS have a 90% risk of developing multiple basal cell skin cancers. About 5% of children with NBCCS will have medulloblastoma.

Researchers are studying the use of a “hedgehog pathway” inhibitor (GDC-0449) in treating people with these cancers who have the PTCHgenetic mutation. This new treatment is a pill which targets the broken hedgehog gene and blocks the activated pathway. Talk with your doctor for more information about treatment options.

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