Hereditary cancer, can it be prevented?

During their lifetime, 1 out of every 3 people will suffer from some type of cancer. Of the total number of cases, between 5 and 10 percent are hereditary.

Nowadays, people who suspect that there is a genetic alteration linked to cancer in their family can undergo genetic testing and, if so, take specific follow-up measures.

Cancer of genetic origin: sporadic vs. hereditary

All types of cancer are genetic in origin, since they are the result of an alteration in the genes responsible for controlling cell growth and division.

However, it should be emphasized that genetic does not mean hereditary. In fact, most cancers (between 90% and 95%), occur sporadically, i.e. due to a genetic alteration that is not hereditary, but is caused by the accumulation over time of changes or mutations in the DNA, related to:

• Age: although cancer can appear in any period of life, a quarter of newly diagnosed cases occur in people between 65 and 74 years of age.

• Exposure to carcinogenic factors in the environment (such as tobacco smoke or solar radiation) and their interaction with genetic variants in the mechanisms of cellular repair and response to carcinogen damage.

Therefore, cancer is always of genetic origin, and this in turn can be hereditary or, more commonly, sporadic.

What is meant by hereditary cancer?

Although most cancers are sporadic, there is a hereditary percentage (between 5% and 10%), which develops due to the presence of a mutation in a cancer susceptibility gene.

For this reason, although we all run the risk of developing some type of cancer at some time in our lives, there are people whose predisposition is several times greater than that of the general population.

Hereditary cancer syndromes are due to a mutation in specific genes, and follow a Mendelian inheritance pattern.

What indicators can make us suspect hereditary cancer?

It is important to learn to identify those factors that may be signs of hereditary cancer:

• Early age of onset: sporadic cancer usually develops after the age of 50. If it starts earlier, the origin could be genetic.
• Several members of a family affected by the same type of cancer or with recognizable patterns, (such as breast and ovarian cancer).
• Development of more than one type of primary cancer (not caused by metastasis).
• Involvement of both organs, when these are pairs. For example, both breasts or both kidneys.
• Rare cancer.

In addition to the situations listed, there are also some genetically based diseases linked to an increased predisposition to cancer. For example:

• Down syndrome: it is caused by the presence of a third copy (partial or total) of chromosome 21, hence it is also known as Trisomy 21. In addition to causing congenital malformations and learning disabilities to varying degrees, it also increases the chances of developing leukemia by 10 to 20 times.

• Noonan Syndrome: caused by a genetic mutation, it results in short stature, facial dysmorphia and congenital cardiac anomalies. It also increases the risk of leukemia and other solid tumors by 3.5 times.

It is important to point out that when several cases of the same cancer occur in a family, this does not necessarily have to be caused by a hereditary cancer syndrome. It can also be a consequence of the specific combination of shared genetic and environmental factors, because the members of the same family usually have the same habits and way of life.

In any case, families who suspect a hereditary cancer syndrome need the attention of a medical geneticist or genetic counselor, who will evaluate this suspicion, and can determine if there are other individuals at risk, as well as indicate if and what type of genetic testing is necessary.

Genetic tests to detect hereditary cancer

The most commonly indicated genetic study in families with suspected hereditary cancer syndrome is the so-called multigene panel. This uses next generation sequencing, an advanced technology better known as NGS (Next Generation Sequencing).

This study allows the simultaneous analysis of a large number of genes related to hereditary cancer syndromes.

In any case, it is the genetic counselor who will indicate which type of genetic analysis is most convenient in each case, and who will propose the various scenarios that we may encounter after performing it, depending on whether the result is positive, negative or inconclusive.

Preventive measures against hereditary cancer

The information provided by a genetic test is really valuable, since knowing the predisposition to a hereditary cancer syndrome allows you to take the various preventive measures that exist to reduce the risk. These include, for example, prophylactic surgeries and/or strict surveillance through analyses or imaging studies.

In addition, for some hereditary cancer syndromes, there are specific clinical guidelines agreed upon by specialists, in which management and follow-up measures are indicated for individuals at risk.

Do you suspect that hereditary cancer may run in your family?

In this case it is very important that you gather all the information available on those affected (age at diagnosis, specific type of cancer and its evolution) and go to a physician or genetic counselor. He or she will be able to determine the risk for family members and assess the need for genetic testing.

If you suspect that you may be among the cases of hereditary cancer and you wish to obtain information about CancerRisk, the Veritas genetic test that analyzes 40 genes related to hereditary cancer, you can contact us without obligation.

If you have no clear history of the disease, but are concerned about your risk of developing it, the myGenome test can help you clarify whether you are at risk of hereditary cancer, as well as give you information on other key aspects to improve your health with informed decisions thanks to whole genome sequencing.