Personalized medicine is a practice in which hereditary genetic information or molecular alterations of the tumor are used to direct the clinical treatment of a patient in an individualized way. It is also useful for a better understanding of the course of the disease and a greater chance of predicting its outcomes.
Individualized treatment aims to optimize outcomes based on the biological characteristics of the tumor and the patient.
Before the rise of personalized medicine, people with the same type of cancer received the same, standardized treatment. With experience and the passage of time, physicians realized that patients’ responses were different.
So the researchers began to analyze the genetic differences that exist in each person and their tumors. These differences offered clues and explanations as to why some patients had such positive results while others did not, even using an identical treatment.
Individualized treatments and oncology
Currently, there are several examples in oncology in which genetic information is used about the person (their genetic constitution) or the tumor they present (genetic alterations found in the tumor). These data are very useful to define the best treatment or preventive measures, making them individualized and specific for that patient, according to their molecular characteristics.
Some genetic tests that help the doctor make decisions about a treatment are:
• Genetic testing of EGFR gene mutations in the tumor to define lung cancer treatment;
• Genetic testing of mutations in the BRAF gene in the tumor to define melanoma treatment; and
• Genetic testing for mutations in the person’s BRCA1/BRCA2 genes (hereditary DNA) to define treatment for ovarian and breast cancer.
Targeted therapy – Targeted therapy is a type of treatment that aims to target a specific gene (previously identified by genetic testing) and proteins that cause the cancer to grow in an uncontrolled way. When using a targeted drug, an attempt is made to prevent this from happening.
Targeted therapies are constantly evolving. Currently, there are options that have been successful for many types of cancer, such as:
• Breast cancer;
• Colorectal cancer;
• Bladder cancer;
• Lung cancer;
• Ovary cancer;
• Leukemia;
• Lymphoma; and
• Melanoma.
Pharmacogenomics – In pharmacogenomics, the study of how an individual’s genes affect their response to a particular treatment. For example, a person may absorb a drug more quickly than other patients. This means that she needs a larger dose for the medicine to work properly. The opposite is also true, when a patient processes the drug more slowly than the others and this causes the drug to remain in the bloodstream for a longer time, which can lead to adverse effects.
With the pharmacogenomic study, the physician receives all this important information and can individualize the treatment according to the characteristics of each patient, offering a higher or lower dose.
Restrictions of personalized medicine and individualized treatment
Not all health plans provide coverage for genetic testing and counseling. In the SUS, some specialized centers provide clinical care (genetic counseling), but few offer genetic testing. When this occurs, it is usually through special institution programs or in clinical trials. The SUS itself has not yet incorporated the genetic test related to cancer in its list of procedures.
It is important to highlight that:
• Tumor genetic testing can help the oncologist to define the best treatment for each case;
• If your doctor identifies something that makes you suspect the cancer is hereditary, he or she should refer the patient for a genetic risk assessment with a specialist;
• Having the information and knowing if there is a genetic risk of having cancer, as well as identifying if the tumor is predominantly caused by a genetic alteration, will bring benefits and increase the chances of preventing the disease in the patient and their families; and
• Individualized treatment offers better chances of results and with a lower risk of adverse effects.
