Genetic Testing and Counseling

21.03.2024

GENETIC TESTS AND GENETIC COUNSELING IN CANCER PATIENTS

Genetic tests have a very important role in cancer treatment. These tests allow us to better understand the nature of the disease and its response to treatment. Especially since some types of cancer are closely associated with genetic mutations, genetic tests are critical in the diagnosis of the disease and evaluation of risk factors by identifying these mutations. Genetic testing helps identify more targeted and personalized treatment options. In this way, treatment side effects are reduced and treatment effectiveness is increased. Overall, genetic testing improves cancer treatment decision-making and provides patients with better, more personalized treatment options.

There are several important reasons for performing genetic testing on cancer patients:

Identification of the Disease and Risk Assessment: Some types of cancer are closely related to certain genetic mutations. Genetic testing can help identify the disease and evaluate risk factors. For example, BRCA1 and BRCA2 gene mutations are known risk factors for breast cancer.

Personalized Treatment Options:Genetic testing can play an important role in cancer treatment. Targeted therapies, in particular, can target cancer cells based on specific genetic characteristics. Thus, treatment methods that are more effective and have fewer side effects can be determined according to the genetic structure of the patient.

Risk Assessment of Family Members: Genetic testing can help determine whether a patient's family members have similar genetic risks. This information allows family members to seek early diagnosis and preventative treatment options.

Course and Prognosis of the Disease: Some genetic changes can provide information about the course and prognosis of cancer. These tests can provide important clues about the course of the disease and response to treatment.

Genetic testing is becoming increasingly important in understanding and treating cancer. While these tests contribute to the development of treatment approaches specific to each patient, they also provide valuable information for the future health planning of the patient and his family.

Image 1: Hundreds of different genetic mutations have been identified that lead to the development of cancer.

EXAMINATION METHODS

Genetic tests in cancer patients are performed using various methods to examine the genetic structure of the cancer and the patient's genetic predisposition to cancer. Each of these methods is designed to detect specific genetic changes and mutations and use this information in treatment planning.

The main genetic testing methods used in cancer patients are:

Polymerase Chain Reaction (PCR): PCR is a technique that rapidly copies and amplifies a specific DNA sequence. This method is used to detect specific gene mutations in cancerous cells.

Fluorescent In Situ Hybridization (FISH): FISH is a technique used to visualize the presence and number of specific genes or chromosome regions in cells. This method is effective in detecting genetic abnormalities and chromosomal changes.

Next-Generation Sequencing (NGS): NGS enables rapid and comprehensive sequencing of genes or the entire genome. This method reveals the genetic profile of cancer in detail by analyzing many different genes simultaneously.

Microdizi Analysis: Microarray technology analyzes genetic changes and mutations by measuring the expression of thousands of genes simultaneously. This method is used to understand the molecular characteristics of cancer.

Sanger Sequencing: Sanger sequencing provides accurate sequencing of a specific region of DNA and is used to detect genetic mutations. This method is useful for detecting previously known mutations.

Copy Number Variation Analysis: This method detects copy number changes in DNA. In cancer cells, there is usually an increase or decrease in the copy numbers of genes.

Each of these methods provides important information for identifying cancer, determining strategies for treatment, and assessing the patient's genetic risk profile. Given the complex nature of cancer, a combination of these tests is often used to obtain the most comprehensive and accurate results.

Image 2: Some cancers, such as breast, colon and ovarian cancer, may show familial transmission.

WHAT ARE THE TYPES OF GENETIC TESTS?

Genetic tests performed on cancer patients are used to provide information about the type and characteristics of the cancer and to determine treatment options. These tests generally fall into two main categories: somatic tests and germline (hereditary) tests.

Somatic Mutation Tests:

Tumor Profiling: This test is used to identify genetic changes in cancer cells. It involves genomic profiling and detects cancer-specific mutations, copy number changes and other genomic changes.

Targeted Panel Tests: These tests are designed to detect known gene mutations for certain types of cancer. For example, it can test for EGFR, ALK, and KRAS gene mutations for lung cancer.

Germ Line (Hereditary) Mutation Tests:

Genetic Predisposition Tests: These tests are used to detect inherited gene mutations that increase a person's risk of developing cancer. For example, BRCA1 and BRCA2 gene mutations may increase the risk of breast and ovarian cancer.

Testing for Familial Cancer Syndromes: Some genetic syndromes may be associated with more than one type of cancer. These tests evaluate the risk for conditions such as Lynch syndrome or Li-Fraumeni syndrome.

These types of tests play a critical role in understanding cancer biology and treatment options. These tests can also be used to guide the genetic counseling and risk assessment needs of patients and their families.

WHO SHOULD BE GENETIC TESTED?

The use of genetic tests in cancer patients depends on the characteristics of the disease, the patient's family history and general health status. Some conditions and types of cancer make a higher priority for genetic testing. Some cancer patients for whom genetic testing is recommended:

Cancers Associated with Family History: Patients with a strong family history of certain types of cancer (for example, breast, ovarian, prostate or colorectal cancer).

Patients with Cancer at an Early Age:Patients diagnosed with cancer, usually under a certain age (for example, before age 50).

Patients with More than One Type of Cancer: Patients diagnosed with more than one type of cancer simultaneously or at different times in their lives.

Rare or Aggressive Types of Cancer: Aggressive types of cancer that are rare or generally thought to be related to genetic factors (for example, some pancreatic cancers, medullary thyroid cancer).

Hereditary Cancer Syndromes: Patients with a history of genetic syndromes that carry a risk of hereditary cancer, such as Lynch syndrome, BRCA1/BRCA2 mutations.

Ethnic Groups: Some ethnic groups may be at higher risk for certain genetic mutations. For example, BRCA mutations are more common in individuals of Ashkenazi Jewish descent.

Patients Who Do Not Respond to Standard Treatments: Cancer cases that are expected to respond to standard cancer treatments but do not respond.

When deciding on genetic testing, it is important to provide genetic counseling to the patient and his family. This helps evaluate the meaning of test results, possible risks, and treatment options. Because each patient's situation is unique, decisions about whether to perform genetic testing should be made considering individual health conditions and risk factors.

Image 3: Genetic evaluation should be performed to evaluate the development of different cancers and familial risk in cancer patients with genetic mutations.

GENETIC CONSULTANCY

Genetic counseling in cancer is a process that helps understand genetic risks, results of genetic tests, and the effects of this information on cancer diagnosis and treatment. This process supports individuals and families to assess their cancer risk, learn about genetic testing, and make health decisions based on genetic information.

Genetic counseling in cancer is especially important for the following groups:

Family History: Individuals in families with a history of cancer may benefit from genetic counseling. This may include more than one person in the family or one or more people having cancer at a young age.

Hereditary Cancer Syndromes: Genetic counseling is recommended for people who are suspected of having genetic mutations that carry a known hereditary cancer risk, such as BRCA1/BRCA2.

Positive Genetic Test Results: For individuals who test positive for genetic testing, genetic counseling helps them understand the meaning of the test results and the implications of these results for the individual's health planning.

Individuals Diagnosed with More than One Type of Cancer: Individuals with more than one type of cancer or rare types of cancer can benefit from genetic counseling.

Genetic Test Results Family Members at Risk:Genetic test results may also carry potential risks for family members. In this case, genetic counseling can help family members understand their risks and take preventative measures if necessary.

Cancer Patients Considering Having Children: Cancer can be passed on genetically. For this reason, individuals who have been diagnosed with cancer and are considering having children can evaluate the risks that may be passed on to their children through genetic counseling.

The process of genetic counseling in cancer generally includes the stages of evaluating family history, discussing genetic tests, analyzing test results and planning precautions to be taken based on this information. This process enables individuals to understand their risks, make informed decisions and take early precautions when necessary.

WHO GIVES GENETIC COUNSELING?

Genetic counseling in cancer is usually given by healthcare professionals with special training and certification in this field. These professionals and their roles can be described as:

Certified Genetic Counselors: These specialists have received specific training in genetic counseling and usually have a license or certification in genetic counseling. Genetic counselors help patients and their families understand genetic test results, make risk assessments, and make health-related decisions based on genetic information.

Oncology Specialists: In some cases, oncologists or other doctors who specialize in cancer treatment may be involved in the genetic counseling process. These experts play an important role in explaining the meaning and importance of genetic test results for cancer treatment and management.

Medical Geneticists: Medical geneticists are physicians who specialize in the diagnosis and treatment of genetic diseases. Medical geneticists with special training in cancer genetics can play an important role in the genetic counseling process.

The genetic counseling process usually includes a detailed evaluation of family health history, genetic testing options, the meaning of test results, and the implications of these results for the patient and their family's health planning. This process helps patients and their families understand their genetic risk, make informed decisions, and implement early and effective treatment or prevention strategies when necessary.