Genetic testing searches a person's genome for certain hereditary alterations or variations. Genetic variations can impact an individual's likelihood of acquiring illnesses in a detrimental, helpful, neutral, or undetermined way.

It is well-recognized that some genes might have harmful variations that raise the risk of cancer. It is estimated that between 5 and 10% of all malignancies are caused by these hereditary variations.

Even when cancer is not brought on by a hereditary variation, it can occasionally seem to "run in families." For instance, comparable malignancies may develop in family members due to a common lifestyle or environment, such as tobacco smoking.

But there are other trends that run in families, such as the kinds of cancer that arise, other illnesses that are not related to cancer, seen, as well as the average age at which cancer manifests itself—may indicate the existence of a hereditary predisposition to the disease.

Numerous hereditary cancer risk syndromes have been linked to certain genes. It is possible to determine whether an illness is truly the consequence of an acquired syndrome by finding out if a person contains a detrimental mutation in one or more of these genes.

Genetic testing, specifically prostate cancer genetic testing, is also performed to find out if a family member known to possess a detrimental (cancer susceptibility predisposing) variation was passed down to family members who have not (yet) got cancer.

When someone has already received a cancer diagnosis, another kind of genetic testing known as tumor DNA sequencing is occasionally carried out to find out if the cancer cells of those individuals have genetic alterations that can be applied to direct medical care.

While some of these alterations in cancer cells may be inherited, the majority happen at random while a person is alive.

Does cancer always come to those who inherit a variation in their susceptibility to the disease?

No. It is not a given that every person who inherits a cancer susceptibility mutation will go on to have cancer, even if the variable runs in the family. Whether a person with this variation will get cancer depends on several factors.

The first is the variant's penetration. Completion or decreased penetrance refers to a variation's ability to prevent all carriers of that variant from developing the illness that is linked to inherited cancer.

The expressivity of a condition refers to how differently individuals who inherit a variation manifest its signs and symptoms, including the emergence of related tumors.

Environmental dangers and lifestyle choices can also affect how an illness manifests itself.

Which genetic testing is available to determine one's risk of cancer?

A person's risk of getting cancer can be increased by a single mutated copy of the genome inherited from one parent, as is the case for the majority of these dangerous variations that are transmitted in a way that is autosomal dominant. Genetic testing for dangerous mutations is recommended for the majority of these illnesses.

Additionally, tests are offered for several inherited genetic variations that have been shown to raise the risk of cancer but are not connected to any specific disorders.

Who ought to think about getting tested genetically for cancer risk?

See a genetic counselor if you are worried about whether your family history increases your risk of cancer.

The following characteristics of a person's individual or medical history of the family may, especially when combined, raise the possibility of a hereditary cancer syndrome:

• The diagnosis of cancer came at an abnormally young age.
• The same person experienced many kinds of cancer.
• Both have cancer.
• Organs that are paired together, as both breasts and kidneys.
• A person's mother, daughter, as well as sisters may all have breast cancer, as well as other first-degree relatives who are their parents', siblings', or children's cancer patients; additional family members may have colon, ovarian, or breast cancer.
• Unusual instances of a certain form of cancer (male breast cancer, for instance)
• The existence of birth defects is known to be linked to hereditary cancer syndromes, such as skeletal deformities linked to neurofibromatosis type 1 and some noncancerous (benign) skin growths.
• Being a part of a racial or ethnic group where there is a recognized higher risk of developing a certain genetic cancer susceptibility syndrome and possessing any number of the afore mentioned characteristics.
• Many relatives suffering from cancer.

When it is feasible, it is advised that a family member who has cancer receive genetic testing (https://www.ama-assn.org/delivering-care/precision-medicine/genetic-testing) and guidance first if the malignancy in the family is suspected to be caused by an inherited biological variant.

This will help to determine with greater certainty whether the malignancies in the family are caused by an inherited susceptibility to cancer syndrome.

When genetic testing is performed on a family member who has been diagnosed with cancer, it frequently yields more revealing results than when it is performed on a person who has never suffered from cancer.