Genetic Testing For Cancer

The American Cancer Society describes genetics as the field of science that looks at how traits are passed down from parents to their children through the genes.  Genes are pieces of DNA inside of our cells that tell the cell how to make the proteins the body needs to function, so DNA is the genetic blueprint in each cell. The genes pass the inherited traits, such as hair color, eye color, height and so on from the parents to their child.  They can also affect if a person is likely to develop certain disease, such as cancer.

Our changes in genes is called mutations, and they play an important role in the development of cancer.  Any mutations can cause the cell to make or not make proteins that affect how your cell grows and divides into new cells.  Some of these can cause the cells to grow completely out of control. This can lead to cancer, but only about 3 to 5% of all cancers are thought to be related to an inherited gene mutation.  It usually requires several gene changes or mutations before a cell becomes cancer.

Acquired mutations affect only the cells that grow from the mutated cell and do not affect all the cells in the person’s body.  All cancer cells will have mutations, but normal cells in the body will not. Mutations are not passed from parents to their children.  This is unlike the inherited mutation in every cell in the body, including the cells without cancer.

Predictive genetic testing is used to look for inherited gene mutations that may put someone at higher risk of getting certain kinds of cancer.  Those with a strong family history of certain types of cancer would be advised to have this testing. Also, for a person already diagnosed with cancer and family members of a person known to have an inherited gene mutation that increases cancer risk.  The testing for these incidents would help to look for cancer early.

Some people may need genetic counseling and testing who have had certain cancers or certain patterns of cancer in their family, as follows:

  • Several 1st degree relatives with cancer
  • Relatives on one side of family having same type of cancer
  • Cluster of cancers in the family known to be linked to a single gene mutation
  • Family member with more than 1 type of cancer
  • Family members having cancer at a younger age than normal
  • Close relatives with cancers linked to rare hereditary cancer syndromes
  • Family member with a rare cancer
  • Ethnicity, such as one linked to an inherited cancer
  • A physical finding linked to an inherited cancer
  • A known genetic mutation in one or more family members who have already had genetic testing

Know your family history and what kinds of tests are available.  These tests may be useful for you, so find out before having them how they will help you.



Dr Fredda Branyon