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Cowden Syndrome

Cowden Syndrome - What is it for

Cowden syndrome, or PTEN hamartoma tumour syndrome, is a hereditary cancer syndrome.

PTEN hamartoma tumour syndrome

PTEN hamartoma tumour syndrome (PHTS) is a hereditary condition caused by a faulty (disease-causing) PTEN gene.

‘Hamartoma’ is a general term for a benign, or non-cancerous, tumour-like growth. PHTS is a broader term which includes Cowden syndrome (CS).

PTEN is a gene that makes an important protein to control cell growth and division. When a fault occurs in the PTEN gene, the protein cannot be made properly and cell growth becomes uncontrollable, which often leads to the development of benign tumours or cancer.

In rare cases, individuals with faults in other genes like AKT1 and PIK3CA can present with features similar to CS. Genetic testing can clarify where the gene fault lies.

What is Cowden syndrome?

CS occurs in an estimated one in 200,000 people. Individuals with CS may develop both benign and malignant (cancerous) tumours in the breasts, uterus, thyroid, gastrointestinal tract, skin, tongue and gums.

People with CS are also at higher risk of developing various cancers.

What is hereditary cancer?

Hereditary cancer makes up about 5-10% of all cases of cancer. Some genes function to protect us from cancer. When they are not working well, it causes hereditary cancer. We refer to genes that are not working well as faulty genes.

Individuals who carry a faulty cancer gene(s) have a higher chance of developing certain cancers over their lifetime compared to the general population. The types of cancers that they may be at increased risk of will depend on the gene(s) involved.

If you have a faulty cancer gene, you may be at increased risk of developing certain cancers. As genes are shared among family, other family members may have inherited the faulty gene and may be at increased risk of cancer too.

Hereditary cancer accounts for up to 10% of all cases of cancer.

What is genetic testing?

Genetic testing is offered to individuals where a hereditary cause of their personal and/or family history of cancer is suspected.

Genes contain the instructions that our body reads to carry out different functions. Genetic testing involves analysing your genes to understand if there are faults (i.e., mutations) that may increase the risk of diseases like cancer.

How is genetic testing done?

  • Genetic testing is typically a one-time blood test.
  • If a blood sample cannot be taken, other sample sources (e.g., skin or saliva) may be used.

What are the possible results of genetic testing?

There are 3 types of results you may receive:


Variant of Uncertain Significance (VUS)

​Faulty gene(s) identifiedUncertain gene change(s) identified, unclear if these change(s) increase risk for tumours and cancers​​No faulty gene(s) identified
Increased risk of developing certain tumours and cancers (depends on faulty gene(s) involved)​May be clarified by testing other family members​​Tumour and cancer risk is similar to that of general population​
Your family (parents, siblings, children and extended relatives) may have inherited the faulty gene(s) and should consider genetic testing to clarify this​May be reclassified over time as ‘positive’ or ‘negative’ when more information is known
​Test limitations will be explained in the context of your personal and family history of tumours and cancers

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