Genetic test and cancer

One of the most interesting advances in recent years in the area of ​​oncology has been the study of genetics and its association with certain types of tumors.

What is a hereditary cancer

A mutation is a change in the information contained in the DNA of cells. These can be innocuous, since they do not alter relevant genetic information in the cell; lead to beneficial effects; or, on the contrary, increase the carcinogenic risk, that is, leading to the development of a tumor.

Hereditary cancers are understood to be those that a person with a certain altered gene presents, which they can transmit to their children.

The vast majority of cancers are not inherited, it is estimated that only about 5 to 10% are. The knowledge of the genetic panels (mutual genes and the cancer with which it is associated) allows the development of different strategies, especially for the prevention and development of this type of tumor in patients who are carriers of that particular mutation.

For example, in women with a certain mutation that has been shown to increase the risk of ovarian cancer, having an oophorectomy (removing the ovaries) removes it completely.

Therefore, the performance of genetic tests in hereditary cancers has been incorporated into routine medical practice.

When and how are they done?

It is suspected that there may be a hereditary cancer in those patients with a special personal or family medical history. These include: the presence of several cases of cancer in the family and / or if they have appeared at an early age; having presented several types of cancer in the same patient, being from a certain ethnic group with greater susceptibility, etc.

Currently, university hospitals in a large number of Spanish cities have so-called Genetic Counseling Units, whose function is to advise, assess and indicate genetic tests in those cases that they consider pertinent.

The procedure for the patient is very simple since it is generally done with a simple blood test, other times with samples of skin cells or saliva. What is studied in the laboratory is the individual's DNA and whether there are the genetic alterations (specific genes) described and associated with hereditary cancers.

How is it interpreted?

The genetic study indicates whether the person, once the mutation has been identified, is a carrier or not. This means whether or not you have inherited the disorder that makes you have a higher risk of a certain tumor. The fact of being a carrier does not mean that the tumor will develop but that there is a greater predisposition than in the rest of the population.

The genetic test is useful both for the patient and for the rest of the relatives since the mutation can be present in several members of the family.

What types of cancer are the most frequently inherited?

• Hereditary breast cancer: BRCA1 and BRCA2 genes involved
• Colon cancer: APC gene
• Skin cancer (malignant melanoma):
• Ovarian cancer: BRCA1, BRCA2 genes
• Medullary thyroid cancer: RET gene
• Other rarer types of cancer: pheochromocytoma-paraganglioma (genes, SDHC, SDHB, SDHA and SDHAF2), multiple endocrine neoplasia (MEN1 gene), retinoblastoma (RB1 gene).

The preventive actions that can be carried out must be individualized in each case, but in general terms they will include surgery (prophylactic mastectomy, for example), chemotherapy (drugs to reduce risk) and early diagnosis (early detection tests, for example). example colonoscopy in colon cancer).

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• The performance of genetic tests in hereditary cancers has been incorporated into routine medical practice.
• The procedure for the patient is very simple since it is generally done with a simple blood test, other times with samples of skin cells or saliva.
• What is studied in the laboratory is the individual's DNA and whether there are the genetic alterations (specific genes) described and associated with hereditary cancers.

Intensive Medicine Specialist