Genetics May Tie Into Certain Types of Cancer

With statistics such as 1 out of 2 men and 1 out of 3 women have a risk of developing some type of cancer in his/her lifetime, it can be difficult to determine if genetics play a role in whether a person is more or less likely to develop cancer throughout his or her lifetime. There are cancers that seem to run in families because of common environmental factors such as smoking, radiation exposure, diet and hormones. Less often, there is an abnormal gene, passed from parent to child, which can lead to the development of cancer. This is the case in only about 5-10% of cancers.

Gene Mutations: Inherited or Acquired
There are two types of gene mutation, inherited and acquired. Inherited mutations are abnormal genes in the DNA that are passed from parent to child. Acquired mutations start with one cell or group of cells that changes over time, increasing the risk of developing cancer. Inherited mutations are present in every cell of the body, whereas acquired mutations are only present in one cell and then passed to offspring of that specific cell. Acquired mutations are much more common than inherited mutations.

Two Main Roles of Genes in Cancer
There are two types of genes that play a part in cancer development, oncogenes and tumor suppressor genes. Oncogenes are a mutated form of a proto-oncogene, and tumor suppressor genes stop cancer from growing. Proto-oncogenes are genes that determine the type of each individual cell, and the rate of growth and division. When these cells become mutated, they are called oncogenes and can cause the cells to grow and divide too quickly, leading to the development of cancer. Tumor suppressor genes slow down cell division, repair mistakes in DNA and tell cells when to die. When these genes become mutated, they lose these characteristics and have the same effect as oncogenes and can cause cells to grow and divide too quickly, therby causing cancer.

Family Cancer Syndromes
There are certain factors that help determine whether cancer runs in a family through inherited mutations.

  1. Several cases of different family members with the same type of a rare form of cancer.
  2. Several cases of cancer, occurring at a younger than average age for that specific type of cancer.
  3. One or more people with two or more different types of cancer.
  4. Cancer occurring in bilateral organs, rather than just one.
  5. Childhood cancer occurring in two or more siblings.

There are several questions that can be answered in order to help determine if cancer does, in fact, run in a family.

How are the family members with cancer related? If everyone with cancer is closely related (i.e. parents and children), the cancer is more likely to be inherited than if they are distant relatives.

  • What types of cancer do they have? If it is a rare type of cancer and more than one member of the family has it, it is more likely to be an inherited mutation.
  • What was the age of the family member when diagnosed with cancer? If members of your family have been diagnosed with cancer at a young age, it is more likely to be an inherited gene mutation.
  • How many types and locations of cancer did the family member have? If family members have two or more different types of cancer, or cancer is in bilateral organs, there is a greater chance it could be inherited.
  • Are there environmental factors such as smoking, high radiation exposure etc.? If there are environmental factors, such as smoking, there is an increased chance that anyone, usually family members, exposed to smoke for an extended period of time, will get cancer in the form of acquired gene mutations, not inherited mutations.
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