All cancer is genetic, in that it is triggered by altered genes. Genes that control the replication of cells become damaged, allowing the cells to reproduce in an uncontrollably.

Cancer usually arises in a single cell. The cell's progress from normal to malignant seems to follow a series of steps, each controlled by a different gene or set of genes.

Most cancers come from random mutations that develop in the genes of body cells over a lifetime, either as a mistake when cells are going through cell division or in response to damage from the environment or from radiation or chemicals for example.

Inherited forms of common cancers

Even though all cancer is genetic, only about 5 or 10 % is due to an inherited predisposition, and the mistake is present in every cell in the body. Inherited forms of breast, ovarian and colorectal cancers account for a small proportion of these common cancers, but the identification of at-risk individuals is important because of the high lifetime risk of developing cancer in gene carriers.

A family history of cancer may be significant if there is one or more of the following features:

• A high frequency of the same cancer within the family and/or
• Early age of onset of cancer.
• Multiple primary cancersin a single individual (such as bilateral breast cancer or several colorectal primaries).

Different types of cancer occurring in families might indicate an inherited predisposition, such as:

• breast and ovary
• breast and sarcoma
• colorectal, uterus, ovary, stomach

WMFACS particularly concentrates on breast, ovarian and colorectal cancers because of the large amount of research of recent years which has greatly increased knowledge regarding the genetic influences in the development of these tumours.

Additionally, management programmes such as mammography and colonoscopy are available for appropriate patients. However, there is a vast amount of ongoing research and development of new knowledge in cancer genetics.

Thus management of other potential family histories of cancers, such as prostate cancer and renal tumours etc. will develop rapidly over the next few years.