What is cancer?
All cancers are caused by changes to materials in our bodies called "genes." These are units of information in every cell of our bodies. Everyone has two copies of each gene, one from each parent. During development, genes tell our cells what type of tissue to become—a skin cell vs. a muscle cell, for example—and in later life, when to divide and make more cells. Genes also determine which proteins to make based on the type of cell and its needs. Some genes tell our bodies how to repair damage from environmental toxins, sun exposure, dietary factors, hormones, and other influences, or tell our cells when to stop growing.
When changes called "mutations" occur in the genes, certain cells can grow out of control and cause cancer. Gene mutations that can lead to cancer usually happen later in life. Over time, these changes occur as a result of the aging process, from exposure to things such as smoke, hormones, certain viruses, certain chemicals or from dietary influences. Not all damage to our cells leads to cancer, however, because our bodies have many methods for repairing damage and because we are all born with two copies of these damage-repairing genes.
When mutations occur in both copies of a gene and cannot be repaired, the damage can lead to uncontrolled growth of the cell, which can lead to cancer. Cancer usually develops slowly, often involving multiple steps (damage to multiple genes), over a period of several years.
What is hereditary cancer?
Hereditary cancers occur when a person is born with a change or mutation in a single copy of a protective gene pair. Because people with an inherited mutation have only one working copy of a protective gene, damage to that remaining gene may occur in fewer steps and over a shorter period of time. This change can increase the risk for certain cancers in different parts of the body. The medical community uses the term "genetic susceptibility" to describe the fact that people with an inherited mutation have an increased risk for cancer.
The change does not increase the risk for every type of cancer and not everyone who is born with a gene change will develop cancer; risks vary according to the exact mutation that was inherited. Many other factors affect the risk of cancer in someone born with a gene mutation. Scientists do not know all the factors that determine whether or not a person with a gene change will develop cancer over the course of his or her lifetime.
The term "hereditary cancer syndrome" describes an inherited gene mutation that increases the chance to develop one or more types of cancer. For instance, the main hereditary breast cancer syndromes—caused by mutations in the BRCA1 or BRCA2 genes—are also associated with an increased risk for ovarian cancer. The main hereditary colon cancer syndrome, called Hereditary Nonpolyposis Colorectal Cancer (HNPCC), can also be associated with an increased risk for ovarian cancer or uterine cancer. Other, rarer cancer syndromes can be associated with a wide variety of cancers.
The Hereditary Risk Assessment Program at the Center for Oncology currently offers testing for patients at risk of hereditary forms of Breast, Ovarian, Melanoma and Colorectal cancers.
For additional information regarding the Hereditary Risk Assessment Program please contact us at 386.238.2219 or you can email us at Cancercare@halifax.org.
