Does Cancer Run in My Family?
This is a very common question, especially if somebody in the family has been diagnosed with cancer. While most cancers do not run in families, a small number of families do have a higher chance of developing certain cancers. This is because members of these families carry a “faulty,” or “defective,” gene that increases the risk of developing cancer. Only a small percentage of cancers (about 5 to 10 per cent) are believed to be caused by such faulty genes. Some cancers that run in family include breast, ovarian, and bowel cancer, retinoblastoma, and melanoma.
Scientists have identified certain faulty genes (changed genes) that run in the family and increase the risk of developing cancer. For example, the presence of BRCA1 and BRCA2 genes increases the risk of developing breast and ovarian cancers, and the presence of the APC gene, found in a condition called FAP, increases the risk of developing colon cancer.
Know the Risk of Developing Cancer
Certain factors place a person at high risk of developing certain cancers. High risk factors for four common familial cancers are discussed below.
Breast and ovarian cancer
The risk of developing breast cancer is high if a person has:
• three or more close blood relatives on one side of the family with breast or ovarian cancer;
• two or more close blood relatives on one side of the family with breast or ovarian cancer who have one or more of the following on the same side of the family:
– cancer in both breasts
– ovarian cancer before the age of fifty
– breast cancer before the age of forty
– breast and ovarian cancer in the same relative
– breast cancer diagnosed in a male relative
– a Jewish background;
• three or more close relatives on the same side of the family with cancer of the bowel or uterus;
• a relative diagnosed with breast cancer at or before age forty-five, and a relative on the same side of the family diagnosed with bone or soft tissue cancer at or before age forty-five; or
• a family member whose genetic test showed a change in the genes associated with breast and ovarian cancer (BRCA1 and BRCA2).
The risk of developing colon cancer is increased if a person has:
• three or more close relatives on the same side of the family with bowel cancer;
• two or more close relatives on the same side of the family with bowel cancer who have any of the following:
– the onset of bowel cancer before age fifty
– more than one bowel cancer in the same relative
– a relative who has had endometrial, ovarian, stomach, small bowel, renal, pelvis, ureter, biliary tract, or brain cancer
– a close relative who has had bowel cancer with a large number of benign tumours (adenomas) throughout the bowel; or
• a family member who has had a genetic test that has shown that he or she has an inherited change in a gene associated with bowel cancer.
The risk of developing melanoma is increased if a person has:
• a personal history of
– melanoma at an early age (average age of familial melanoma is thirty-three years),
– more than one primary melanoma,
– a large number of moles (more than ten on the arms and two hundred on the body),
– multiple atypical moles, or
– a family history of melanoma; or
• a family history of
– multiple cases of melanoma on the same side of the family,
– a melanoma occurring at an early age,
– ocular (eye) melanoma,
– pancreatic or breast cancer in more than one family member, or
– several relatives who have the same type of cancer.
Certain features indicate the possibility that the cancer may be running in one side of the family. These features include:
• several cancers of the same type being diagnosed in the family;
• family members diagnosed with cancer before the age of fifty;
• rare cancers diagnosed in the family, such as retinoblastoma or eye melanoma;
• family members diagnosed with multiple cancers, such as cancers of both breasts;
• two or more cancers diagnosed at the same time, such as cancer of the breast and ovary;
• a family member whose genetic test shows a faulty gene that increases the risk of developing cancer, such as BRCA1 and BRCA2 for breast cancer.
If a person has features that suggest a cancer could be running in the family (discussed above), the person may need genetic counselling. The doctor will refer him or her to a genetic counsellor. Sometimes doctors or nurses who have undergone special training in genetic counselling can be genetic counsellors. The genetic counsellor will discuss the chances of the person developing the cancer; the benefits, advantages, and disadvantages of genetic testing; the person’s eligibility for genetic testing; a management plan for the condition; and many other things.
A new book on cancer ‘DO I HAVE CANCER?’ is now available for sale in many stores around the world. The book describes signs, symptoms, diagnosis and treatment of over fifty common cancers. Besides this, the book also discusses other issues relevant to cancer patients, including sex and sexuality, psychological problems, cancer in children, pregnancy, HIV/AIDS, family cancers, palliative care and euthanasia, lifestyle issues, and the prevention of cancers. The book is intended to be a ‘one stop shop’ for all cancer information. You can order a copy of the book by clicking the links below:
Or if you are in Australia, you can order a copy of the book for AUD 20.00 including postage charge by ordering at:
You will be sent a payment link and the book will be posted upon receiving payment through Australia Post.