Some types of cancer are known to run in certain families’ histories. However, most cancers are not linked to genes and therefore one does not inherit the disease from their parents. This section uncovers the links between genes and cancer as well as genetic testing and how it is used.
With research stating that cancer strikes one in two men, and one in three women, it is no wonder that many families have a few members who have, or have had cancer. Although the numbers are small, some cancers do run in families.
A family history of cancer can be caused by a number of factors. A lot of times family members have similar lifestyle risk factors such as smoking, and sun exposure that can cause cancer. Conversely, in some cases lifestyle factors are not the cause of a family history of cancer. Sometimes the disease is caused by an abnormal gene that is being passed along from generation to generation. It is important to note that the abnormal gene that can cause cancer gets inherited and not the cancer itself. Only 5% to 10% of all cancers are inherited.
Cancer is a disease that thrives off abnormal cell growth and function. Genes are pieces of DNA that contain instructions on how to make proteins the body needs to function, when to destroy damaged cells and how to keep the whole process in balance. Your genes are responsible for physical features such as eye color, hair color, and height. They also have the ability to affect your chance of getting certain diseases such as cancer.
Mutations are caused by abnormal changes in a gene. These genes are passed from parent to child by either the egg or the sperm and live in every cell in the body. However, most mutations that occur are not present in the egg or sperm. These mutations are called somatic mutations and are acquired at some point during a person’s life. Somatic mutations occur in one cell and then are passed to any new cells that are the offspring of that cell.
Research has found that genes have two major, opposite, roles in the development of cancer. Genes called oncogenes can cause cancer while others known as tumor suppressor genes stop cancer from growing.
When an individual inherits an abnormal gene, their cells already start out with one mutation. This makes it easier and quicker for ample amounts of mutations to build up and turn a cell cancerous. That is why those who inherit cancer tend to be diagnosed early on in life, whereas those with the same cancer might not be diagnosed until a lot later in their life.
It can’t hurt to get tested if cancer runs in the family. Below are a list of uses of genetic testing.
- Predictive: this is used to look for a gene mutation that might put a person at a higher risk of getting cancer. For example, tests a female for changes in the BRCA1 and BRCA2 genes whose mother and sister had breast cancer.
- Carrier: this can aid couples looking to start a family see if they are predisposing their children to genetic mutations. This will show some disorders they are likely to pass on to their kin such as sickle-cell anemia, cystic fibrosis or Tay-Sachs disease.
- Prenatal screening: this can be used to diagnose conditions in babies before they are even born, such as Down syndrome.
- Newborn screening: the most widespread form of genetic testing, newborns can be screened for a variety of inherited conditions such as phenylketonuria (PKU), cystic fibrosis, sickle cell disease etc. Some states require genetic tests be done on babies.
Cancer related genetic tests are mostly done for predictive reasons, they can either be used to see if a person has a certain genetic mutation or just to confirm a suspected mutation in an individual.
Mesothelioma and Genetics
As genetics already account for fewer than 10% of all cancer causes, patients diagnosed with mesothelioma have even less of a chance that their cancer was caused by genetics. Typically linked to asbestos exposure, mesothelioma has very little research linking the disease to genetics. Nevertheless, among people born in a few small villages in Turkey, 50% of all deaths are caused by malignant mesothelioma. This epidemic has been found to be attributed to erionite, a fibrous mineral (like asbestos) commonly found in the region. The strange part was that only certain houses were plagued with mesothelioma, while other families went on with their daily lives untouched by the problem.
Studies showed that when a high-risk family married into a family with no history of mesothelioma, malignant mesothelioma appeared in the children. Also, genetically predisposed families born and raised outside of the erionite affected areas did not seem to develop malignant mesothelioma. To sum up the study, pedigree and mineralogical studies specify that the malignant mesothelioma epidemic is caused by erionite exposure in genetically predisposed individuals. This study marks the first time that genetics has been proven to influence mineral fiber carcinogens.