The old adage that you can choose your friends but not your family holds true when looking at your cancer risks.

Today people live for longer than at any other time in history. For instance in the 19th century, more babies died from disease, men and children died early working in the mines, plagues carried off the frail, women died in childbirth, and 40 was considered a ripe old age!

So, even though cancer did exist back then, and people still died from it, the death toll from cancer did not seem that high because people died of many other things long before they were ever at risk of getting cancer. Today more people live until well into their 80s and 90s, with 1 in 4 people over 70 having some type of cancer. This is not due to an increase in cancer, but rather due to more opportunities in our body’s cells to become abnormal and the inability of our bodies to clean out these abnormal cells.

1 in 4 people over 70 will have a cancer.

It is not uncommon for more than one member of a family to have cancer. Cancer can occur in families:

  • By chance (most common)
  • Because family members have risk factors in common (such as environmental and lifestyle influences)
  • Because there is an inherited faulty gene causing an increased chance of cancer (uncommon)

How do I know if my family carries a faulty gene?

Trying to find information about cancers in your family and how to deal with them can be difficult. It is important to know your family history on both your mother’s and father’s side of the family. Even the faulty gene for ‘female’ cancers like breast and ovarian can be inherited from your father.

Only a small amount of some cancers (up to 10%) are due to a faulty gene which is inherited from either your father or mother. This is called a familial cancer. This can also be described as an inherited risk of cancer. The faulty gene increases the risk of cancer, but it certainly does not mean every family member that has this gene will develop cancer.

Clues that the cancer that runs in your family may be due to an inherited faulty gene include:

  • Number of relatives from your bloodline who have had cancer: The more blood relatives who have had cancer (particularly clusters of breast, ovarian and/or bowel/melanoma/thyroid cancer) the more likely the cancer is due to an inherited faulty gene.
  • A young age when the familial cancers occur: The younger a person is 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 different cancers in the family: The type of cancer a person has and who it affects in the family are important. In some families, all patients may develop the same type of cancer, such as breast or bowel cancer. In other families, different sorts of cancer will cluster together (e.g. breast, ovarian or bowel cancer, and cancer of the uterus). This happens because some faulty genes can cause more than one type of cancer.

The more clues that are present, the more likely it is that there is an inherited faulty gene in the family causing the higher than usual chance of getting cancer. But this does not mean you will develop the cancer, just that you have an increased risk and need to be more vigilant with screening.

What should I do if I have a family history of cancer?

Remember, you can’t change your family genetics, but knowing about all the cancers in the family is important. Try to find out what types of cancer your relatives have had and how old each person was when they developed the disease as well as who was not affected by cancer. Family history of cancer can change over time as other people be- come part of the family. Different cancers in the family are often due to a combination of genetics and may not be a single faulty gene. This is a bit like a lock combination for a family, such as “3;2;1” and may not be able to be detected by genetic tests that can’t work out combination of genes. It is important to keep the doctor updated about any new cancers diagnosed in the family.

Family counselling and genetic counselling services

Genetic counselling services give people information about their chance of developing cancer based on their family history. These specialists will spend time explaining how to be more vigilant with screening for cancer and how modifying diet and lifestyle factors may decrease risk. It may be that genetic testing is possible, particularly if a member of the family who has cancer can be tested. This is only carried out after the advantages and disadvantages of testing for the patient and their family have been discussed.

After female gender and advancing age, a positive family history of cancer is the strongest risk factor in developing breast cancer. In most cases there is not a long and extensive history of cancer present (more than four relatives in the same line). However, in some families there is a strong hereditary line of cancer characterised by cancer at a young age; cancer in both breasts, as well as clustering of different cancers of the breast (primarily ovarian and male breast cancer). Only less than 8% of all breast cancers will be due to these genes, which are known as BRCA1 and BRCA2. Others, which are less well known, are TP53, PTEN/MMAC1 and STK11. There is testing available for the BRCA 1 and 2 genes for patients with a significant family history.


Managing patients and families who have a strong family history, or a positive genetic test is highly specialised and requires a team approach to management. Close communication between breast specialists and genetic specialists and discussions about screening, early detection and risk reducing surgery should be managed only in a specialist unit. Risk reducing surgery is not “aesthetic surgery” but rather reconstructive, it is not as simple as “Barbie breasts for life”.


Studies have shown that it is possible to reduce the number of women dying from breast cancer by 45% using simple measures. These include understanding your risk of having breast cancer based on your personal and family history and being screened regularly for breast cancer.