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Cancer in the Family

Cancer Information for Health Professionals

Some people have an increased chance of getting cancer because of their family history. Around 5% of certain cancers are due to inherited gene faults. 

Faulty genes and cancer

Around 1 in every 2 Australians will develop cancer by the age of 80. Most cancer is due to aging and/or environment (e.g. smoking, sun exposure, etc.), but genetics is also a factor. Certain genes protect us against cancer by controlling cell division, growth, and repair. When a person is born with a fault in a cancer protection gene, they have a higher chance of getting certain cancers. About 5% of certain cancers may be due to inherited gene faults.

Read more: Genetic Fact Sheet: Cancer Genetics Overview

How can I tell if my family history of cancer is of concern?

Cancer can occur in multiple family members for different reasons including:

  • Just by chance (mostly the case)
  • Shared environment or lifestyle (eg, too much sun or smoking)
  • Having an inherited gene fault.

Look at both your mother and father’s side of the family. Important features include:

  • The number of relatives on the same side of the family who developed cancer. The more blood relatives who have developed cancer, the more likely the cancer is due to a gene fault
  • The types of cancer in your relatives. Faulty genes usually predispose to specific cancer types.  In some families, people will develop the same type of cancer (such as breast cancer). In other families, the cancer types might have a known genetic link (such as breast and ovarian cancer or bowel cancer and uterine cancer)
  • The age at which cancers in the family developed. Cancers occurring at young ages are more likely to have a genetic cause. For example, breast cancer diagnosed under 40 or bowel cancer diagnosed under age 50.

If your family has one or more of these features, you may be at increased risk of cancer.

Read more: Brochure: What if I have a Family History of Cancer?

What should I do if I am worried about my family history of cancer?

Record your family history by finding out:

  • What types of cancer have occurred in your family
  • How old each person was when they got cancer
  • Also record the family members who have not had cancer
  • Find out whether any of your relatives have had a genetics assessment.

Talk to your doctor:

Your doctor can help you find out if your family history of cancer is of concern. Your doctor may refer you to a Family Cancer Clinic to have your family history assessed.

Read More: Collecting a Family Health History

Brochure: What if I have a Family History of Cancer

What types of cancer can be genetic?

Up to 5% of certain cancer types may be due to inherited gene faults. Some types of cancers due to faulty genes are:

  • Breast and Ovarian Cancer
  • Bowel and Uterine Cancer
  • Melanoma
  • Prostate Cancer

Other cancers may also have a genetic basis. It is therefore important to look at all the different types of cancer that have occurred in the family.
Cancers that are very unlikely to have a genetic basis include:

  • Lung cancer and other smoking-related cancers
  • Cervical cancer
  • Lymphoma and leukaemia
  • Cancers occurring at an old age.
Breast and Ovarian Cancer

Inherited faults (mutations) in the BRCA1 and BRCA2 genes increase the risk of breast and ovarian cancer. Both men and women can carry BRCA1 or BRCA2 gene faults. Features in a family that may indicate a BRCA1 or BRCA2 fault include:

  • Three or more people with breast cancer
  • Early age of onset e.g. breast cancer under age 45
  • Ovarian cancer in the family
  • Male breast cancer
  • Bilateral (in both breasts) cancer
  • Ashkenazi Jewish Ancestry.

Other rare genes that can increase breast cancer risk include TP53, STK11, CDH1, PTEN. Families with faults in these genes usually have additional uncommon cancer types.

Read more: Fact Sheet: Breast and Ovarian Cancer and Inherited Predisposition

Booklet: Understanding Genetic Tests for Breast and Ovarian Cancer that runs in the Family, Information and Decision Aid.

Bowel Cancer

There are a number of gene faults that can cause bowel cancer to run in families. The two most common genetic conditions that lead to bowel cancer are:

  • Lynch Syndrome (or HNPCC): Lynch Syndrome is due to a mutation in the MLH1, MSH2, MSH6 or PMS2 gene. A family history of bowel, endometrial (uterine), ovarian, stomach and kidney cancer can be an indication of Lynch Syndrome
  • Familial Adenomatous Polyposis (FAP): FAP is caused by mutations in the APC gene. People with FAP usually develop hundreds of polyps in the large bowel from a young age.

Key features in a family that indicate a bowel cancer gene fault include:

  • Three or more people with bowel and/or uterine cancer
  • Early age of onset, e.g. under age 50
  • Multiple bowel cancers in one person
  • Many pre-cancerous polyps in the bowel
  • Family history of other cancers such as stomach, ovary, pancreas, kidney cancer.

Other rare genes that can increase bowel cancer risk include MUTYH, STK11, BMPR1, SMAD4, PTEN. These can usually be diagnosed based on the type of bowel polyps or other cancer types.

Read More: Fact Sheet: Bowel Cancer and Inherited Predisposition

Booklet: Understanding Genetic Tests for Lynch Syndrome: Information and decision aid.

Melanoma

Key factors that influence a person’s chance of developing melanoma are:

  • Sun exposure
  • Number of moles an individual has
  • The colour of an individual's skin and
  • Family history of melanoma.

A small number (1-2%) of melanomas are due to faults in genes called CDKN2A or CDK4. Important features that might indicate a melanoma gene fault are:

  • Three or more relatives with melanoma
  • Early age of diagnosis
  • Multiple melanomas in one person
  • Melanoma in areas of skin with low sun exposure
  • Rare types of melanoma
  • If there is also pancreatic cancer in the family.

Read more: Fact Sheet: Genetics and Melanoma

Prostate Cancer

Key factors which influence a man’s chance of developing prostate cancer are:

  • Age. More than two-thirds (70%) of all prostate cancers are in men over the age of 65
  • Having a family history of prostate cancer.

It is thought many genetic factors are associated with the development of prostate cancer. A small number of prostate cancers are due to faults in BRCA1 or BRCA2. Men with a BRCA1 or BRCA2 gene fault will usually have a family history of breast and/or ovarian cancer.

Read more: Fact Sheet: Genetics and Prostate Cancer

Prostate Cancer Screening: Decisions for men with a family history of prostate cancer

Genetic Testing for Cancer Risk

Genetic testing is sometimes able to identify the cause of cancer in a family. An assessment at a family cancer clinic can determine if genetic testing is appropriate in your family.

Usually testing begins with a mutation search of a person who has had cancer.

If a gene fault is identified, predictive testing is available to relatives to see if they have inherited the gene fault or not.

Read more: About public and private genetic testing for cancer risk

Booklet: Understanding Genetic Tests for Breast and Ovarian Cancer that runs in the Family, Information and Decision Aid.

Understanding genetic tests for men who have a family history of breast and ovarian cancer 

Understanding genetic tests for Lynch syndrome

What is a Family Cancer Clinic?

Family Cancer Clinics provide genetic counselling for people with a family history of cancer. This includes people who have not had cancer themselves.

The information and advice provided at a Family Cancer Clinic includes:

  • A family history assessment
  • Individual's chance of developing cancer
  • Appropriate screening advice
  • Cancer risk reduction strategies
  • Genetic testing (where appropriate).

The clinics are held in the public hospital system and there is no direct cost to the patient.

Read more: What is Genetic Counselling?

Find a Family Cancer Clinic

How can I attend a Family Cancer Clinic?

There are two ways you can attend:

  • Your GP, physician or surgeon may refer you to a clinic
  • You can call one of the Family Cancer Clinics to discuss an appointment.

Before you attend, collect you family history details to bring to your appointment.

Find a Family Cancer Clinic

Collecting your family health history

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