MADRID, 24 May. (EDITIONS) –
All the cells of our human body contain in the genetic code the DNA molecules, the information that allows them to carry out their functions normally. You could say that it is the instruction manual of the cellular machinery. The smallest unit of information is called a ‘gene’ and of each we have two copies, one inherited from our mother and one from our father.
“The action of some external agents (such as chemical substances, including the components of tobacco, radiation, infections) and internal agents (derived from the metabolism itself) on cells can alter said code in such a way that the ‘instruction’ is erroneous or does not occur, this is called a ‘mutation’. When both copies of the gene are mutated, the cell stops working properly and disease can occur.“Dr. Ana Beatriz Sánchez Heras, coordinator of the SEOM section on familial and hereditary cancer, explains in an interview with Infosalus.
The also head of the Genetic Counseling Unit in Cancer and Oncogynecology of the Medical Oncology Service of the University Hospital of Elche also mentions that in the case of cancerous diseases, the alterations are mainly concentrated in those genes that control cell multiplication to occur properly, such as the genes that participate in DNA replication and repair, or the genes that regulate the steps of the different phases of the cell cycle.
“If a mutation occurs in the first copy of the gene, the cell continues to function normally, but when another mutation occurs in the second copy of the gene is when uncontrolled multiplication and proliferation begins, which over time it becomes a tumor. That is, it takes two alterations, one in each copy of the gene, to trigger the malignant transformation of the cell, “he adds.
Some people inherit a copy of one of these genes that has already been mutated and is present in all of their cells. In them, a single mutation in the other copy will trigger tumor development, underlines the specialist member of the Spanish Society of Medical Oncology.
“We say that these people suffer from a syndrome of predisposition to hereditary cancer, but not to just any cancer but to specific types. This depends on the gene involved,” warns the expert, detailing that, for example, people with Lynch syndrome, due to to mutations in any of the MLH1, MSH2, MSH6 or PMS2 genes, they have a high predisposition to colon cancer, endometrial cancer, or ovarian cancer “, emphasizes the doctor.
Sánchez Heras also maintains that in hereditary breast and ovarian cancer syndrome, due to mutations in the BRCA1 or BRCA2 genes, women have a high probability of developing breast cancer and ovarian cancer, and men have prostate cancer and cancer of the Mommy.
To this day he maintains that there are surveillance programs to be able to do an early diagnosis of the tumor and thus achieve its cure. “In addition, tumors with certain mutations are more sensitive to certain drugs, so the treatment of the disease can be more precise and personalized,” celebrates the expert.
Moreover, he points out that today we know many genes for predisposition to cancers (just over 200 syndromes, most of them very rare), high risk and moderate risk. “The classification of high and moderate risk is made when comparing with the normal risk of this cancer in the general population. We call high risk a risk that exceeds 4 times the population risk, and moderate risk that is between 2 and 4 times the population risk. population risk “, specifies the oncologist.
As he defends, Identifying people carrying mutations in them allows establishing early diagnosis programs adapted to the type of associated risk, or even perform preventive surgeries in high-risk cases. “In this way the life expectancy for them would be comparable to that of the general population,” he adds.
THE ROLE OF GENETIC TESTING
At the time of making her diagnosis, Dr. Sánchez Heras maintains that genetic tests are indicated in those people who are suspected of being carriers of hereditary mutations predisposing to cancer, either due to the characteristics and age of diagnosis of the tumor (This is the case of high-grade serous ovarian cancer, or also breast cancer before 40 years of age or colon cancer before 50 years of age) or by the presence of several cases in the family throughout successive generations.
“Or when tumor genetic analysis has been done for therapeutic purposes and the results indicate a possible hereditary component. There are established criteria for each known syndrome, which are different according to the suspected syndrome,” adds the head of the Genetic Counseling Unit in Cancer and Oncogynecology of the Medical Oncology Service of the University Hospital of Elche.
The result of the study has family implications, since if a mutation is identified, the direct study can be offered, knowing its status as a carrier or non-carrier, and thus follow the established programs for early detection of cancers at risk, as justified.
In this sense, The head of the SEOM indicates that in Spain more than 20 years ago the Units or Consultations of Family and Hereditary Cancer began to be created: “Many depend on the Medical Oncology Services, since medical oncologists are the professionals who can most frequently suspect a syndrome of predisposition to cancers, observing the characteristics of the tumor and the personal and family history of the patient.”
The professional also clarifies that in each autonomous community the development model of these units has been different and in few cases have they been promoted and organized by the Administration, most as an initiative of the Medical Oncology or Clinical Genetics services of public hospitals and private.
“Patients who are candidates for a genetic study can be referred from Specialized Care and Primary Care. The public health system covers these studies, following the ‘cascade’ model: first, the patient suspected of being a carrier of a hereditary mutation is studied and if confirmed and identifies the mutation, then the direct relatives of the first degree are studied and then, successively, the direct relatives of the identified carriers “, lists the member of the SEOM.
The initial study in a person does not affect cancer from a suspicious family is not usually considered, since a negative result (not detecting any mutation) does not guarantee that other relatives do not have it, as it continues.
“In public centers this type of study is not usually carried out. But surveillance recommendations can be established by assessing the risk according to family history as long as a family mutation can be identified. In fact, today, only identifies a genetic mutation in approximately 30% of families with aggregation of several cases of cancer. We must not forget that with our relatives we share something more than genetics, such as exposure to external environmental factors (chemical, physical), habits life, or exposure to infections, “says Dr. Sánchez.
In recent years, he recalls that the so-called studies or direct-to-consumer tests have appeared, ‘on-line’ offers of studies for genetic diagnosis, which lack correct information, adequate advice and the explanation of the limitations of the possible results. “Obviously they are not recommended,” says the coordinator of the SEOM section on familial and hereditary cancer.
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