Family history of cancer

What is a family history of cancer?

Cancer is common – many people have someone in their family who currently has or has had cancer. It is not uncommon for more than one member of a family to have cancer.

Cancer can occur in families:

  • Just by chance, which is most often the case;
  • Because family members have environmental and lifestyle influences in common, for example too much sun or smoking; or
  • Because there is an inherited faulty gene which leads to an increased risk of cancer, which is uncommon.

Only a small percentage of certain cancers (up to 5%) are due to a faulty gene inherited from either the father or mother. This is what we call a familial or family cancer. This can also be referred to as an inherited predisposition to cancer. The faulty gene increases the risk of cancer, but even then it does not mean every family member will develop the cancer.

Trying to find information about cancers in your family and how to deal with them can be difficult. The following pages provide simple information about what it means to have a family history of cancer, some different types of family cancers and who you can contact for further information.

The information contained in this section should not be used for individual medical advice. Please see your doctor if you have concerns or specific questions relating to your health.

How can I tell if my family has a history of cancer?

Look at the family history on both your father’s and your mother’s side of the family. The clues that cancers in the family may be due to an inherited faulty gene include:

Number of blood relatives* who have had cancer

The more blood relatives* who have had cancer (in particular breast, ovarian and/or bowel cancer), the more likely the cancer is due to an inherited faulty gene.

Ages at which cancers in the family developed

The younger people were when they developed cancer (compared to what is expected in the general community), the more likely it is to be due to inherited factors.

Pattern of cancer in the family

The type of cancer and who it affects in the family are important. In some families there are a number of blood relatives* who develop the same type of cancer, such as breast or bowel cancer. In other families there are some cancers that may run in the family (eg. breast, ovarian or bowel cancer and cancer of the uterus). This happens because some faulty genes can cause more than one type of cancer.

*A blood relative is someone related by blood (eg. grandmother, father, sister), not marriage.

The more clues that are present, the more likely it is that there is an inherited faulty gene in the family causing a higher than usual chance of cancer. However, it is not definite. It is important to know that some people who inherit a faulty gene which causes an increased risk of cancer never go on to develop cancer.

Family counselling and genetic counselling services

Genetic counselling services give people information about their chance of developing cancer based on their family history.

These services discuss ways that may help reduce the chance of cancer developing and methods of picking it up early. Sometimes genetic testing is possible, however it is only offered after the advantages and disadvantages of testing for the person and their family are discussed. Genetic testing is only useful if one of the family members with the cancer has been tested.

For more information about family cancer and genetic counselling services contact your doctor or Cancer Council Helpline on 13 11 20.

Types of family cancer

Familial adenomatous polyposis (FAP)

Familial adenomatous polyposis (FAP) is a rare inherited condition. Less than 1% of all bowel cancers in the general population are due to FAP.

People with FAP usually develop multiple (hundreds to thousands) small growths, called polyps, which carpet the colon. The polyps are adenomatous, which means they are immediate precursors to colon cancer. These generally appear in the teenage years and, if left untreated, inevitably progress to bowel cancer.

For those who have inherited the gene change, regular bowel surveillance is extremely important. Screening, generally by colonoscopy, is required to commence between the age of 10 to 15 years.

For further information click here.

 

Hereditary non-polyposis colorectal cancer (HNPCC)

Hereditary non-polyposis colorectal cancer (known as HNPCC) is a rare inherited bowel cancer syndrome. Less than 5% of all bowel cancer cases are HNPCC.

People with HNPCC often develop large bowel cancer before the age of 50. They commonly have one or more adenomas (small polyps) in the bowel.

People not only have an increased chance of developing bowel cancer, but also cancer of the uterus and other types of cancer including ovary, kidney, ureter (tube that leads from the kidney to the bladder) small bowel,stomach and pancreas.

  (Hyperlink to Types of Cancer above)

For further information click here.

 

Hereditary breast and ovarian cancer (BRCA1 and BRCA2)

About 5% of breast and ovarian cancers are due to an inherited faulty gene. Two genes involved in hereditary breast and ovarian cancer are often referred to as BRCA1 or BRCA2. Their names come from the abbreviation of the genes ‘Breast Cancer One’ and ‘Breast Cancer Two’.

For further information click here.

 

Neurofibromatosis 2 (NF2)

Neurofibromatosis 2 (NF2) is a rare inherited disorder which causes tumours to grow on various types of nerves and which can also affect the development of non-nervous tissues such as the bone or the skin. Signs of NF2 usually appear when people are in their 20s, however may occur earlier or later in life.

Further information:

  • NF2 and genetic testing for clinicians
  • NF2 and genetic testing for families

 

Retinoblastoma

Retinoblastoma is a very rare tumour of the immature cells of the retina in one or both eyes. This only occurs in babies or toddlers under the age of five. Some children have an inherited form of retinoblastoma.

Further information:

  • Retinoblastoma and genetic testing for clinicians
  • Retinoblastoma and genetic testing for families

 

Melanoma

Less than 5% of all melanoma is due to an inherited faulty gene. It may occur in families where there are multiple cases of melanoma on the same side of the family and the presence of atypical or unusual moles, where melanoma occurs at an early age, and sometimes if ocular (eye) melanoma and pancreatic cancer is in the family.

 

For further information click here.

For further information on family cancers

Tasmanian Clinical Genetics Service (TCGS)