Oncology - a risk for the development of hereditary cancer
Oncological diseases arise from the interaction of genetics and numerous internal and external factors. Harmful agents acting on the DNA molecule can cause changes (mutations) that may lead to the formation of tumor cells. The main features of malignant tumor cells are uncontrolled division and damage to surrounding tissues and organs where they spread (metastasize). Genes are parts of DNA that carry instructions for protein creation, and thousands of gene changes (mutations) that aid in the formation, growth and spread of tumors have been discovered through scientific research. Changes in our genes can lead to the development of benign and malignant tumors in various organ systems. It is now known that DNA changes that cause tumors can occur in genes (parts of DNA) called oncogenes and tumor suppressor genes. Changes in oncogenes lead to increased protein production that instructs cells to continue growing and dividing. Changes in tumor suppressor genes, on the other hand, lead to decreased protein production that prevents cells from dividing and growing uncontrollably, and some gene mutations lead to the loss of proteins that tell cells to self-destruct when damaged. Some changes that cause tumor formation occur outside of genes, in non-coding DNA parts that play an important role in regulating the expression of nearby genes. The human DNA is made up of 1.5% coding DNA (genes) and 98.5% non-coding DNA (regulatory and structural regions).
For a healthy cell to become cancerous, more than one mutation must occur in the same DNA molecule, and it is estimated that about 50 mutations in different genes are required for the formation of a cancerous cell. People who inherit a genetic mutation associated with cancer are more susceptible to further mutations, and fewer additional mutations are required to develop cancer and other malignancies. However, in the case of a healthy lifestyle, avoiding harmful substances such as tobacco smoke, and with the help of a healthy diet based on a genetic profile (nutrigenetics), some people may never develop cancer, even though they have inherited a genetic mutation that increases the risk of cancer.
Several types of genetic changes can lead to tumor formation. A mutation is a pathogenic genetic variant that arises from a change in the DNA code consisting of 4 letters representing nitrogenous bases: A-adenine, G-guanine, C-cytosine, and T-thymine. Some genetic changes involve replacing only one letter in the DNA, which is called a point mutation. For example, in people with colon cancer, a common occurrence is a point mutation in the KRAS gene that occurs by replacing the letter G with A within the DNA. This single-letter change creates an abnormal KRAS protein that continuously instructs cells to divide and grow. Most chronic myeloid leukemias are caused by a chromosomal rearrangement that binds part of the BCR gene to the ABL gene. This rearrangement creates an abnormal protein, called BCR-ABL, which leads to uncontrolled growth and division of tumor cells. Also, there are other DNA changes, known as epigenetic changes, that participate in the regulation of gene expression and contribute to the process of tumor formation. Unlike genetic changes, epigenetic changes (sometimes called epimutations) can be reversible and do not affect the DNA sequence, but they can alter the amount of protein that a gene produces.
There are numerous substances, chemicals, and microorganisms in the environment known as mutagens that can cause mutations and epimutations and promote the development of cancer (carcinogens). The most common examples of carcinogens are those found in tobacco smoke, heavy metals like cadmium, UV rays, viruses such as Epstein-Barr virus and human papillomavirus (HPV), and bacteria like H. pylori. While most genetic changes are not harmful in themselves, the accumulation of pathogenic changes (mutations) over many years can transform healthy cells into cancer cells. Most cancers occur randomly as a result of this process over time, which is why cancer is most often seen in older age and the result of the accumulation of mutations that have been occurring for over 20 years.
The most well-known inherited types of cancer
Certain types of cancer can be inherited, with the most famous examples being hereditary colon and breast, and ovarian cancers. Thanks to the discovery of mutations in the BRCA1 and BRCA2 genes and modern methods of molecular biology, there has been significant improvement in screening and treatment decisions for breast and ovarian cancer. Gene mutations that increase the risk of developing tumors can be passed down (inherited) if they are present in the parent's egg or sperm cells. For example, if a parent passes on a mutated BRCA1 or BRCA2 gene to their child, the child will have a much higher risk of developing breast cancer and several other types of tumors. This is why cancer sometimes seems like a disease that runs in families, although it is only an increased risk for developing cancer that is inherited. Up to 10% of all known tumors today may be caused by inherited mutations. Inheriting a genetic change associated with cancer does not mean you will get cancer. It means that your risk of developing cancer is increased.
In some families, there are hereditary tumor syndromes which are rare disorders in which family members have an increased risk of developing certain types of tumors. Hereditary tumor syndromes are caused by inherited mutations in genes associated with cancer. For example, familial adenomatous polyposis is an inherited tumor syndrome caused by changes in the APC gene. People with familial adenomatous polyposis have a very high risk of developing colon cancer at an early age, but also have a risk of developing other types of tumors. However, not all forms of cancer that appear to "run in the family" are caused by hereditary cancer syndromes. Shared environment and lifestyle factors, such as exposure to polluted air or tobacco use, can cause the same type of cancer to develop among family members, such as lung cancer. Additionally, cancer can appear in a family if family members have a combination of a larger number of genetic variants, each of which has a very small risk of developing cancer.
The St. Catherine Special Hospital performs the My Genome genetic test for early detection of individuals with an increased risk of developing cancer and other malignant diseases by analyzing a total of 524 genes and associated mutations associated with tumor risk.
By changing their lifestyle and developing poor dietary habits, people become more prone to the most common diseases of today, which include various types of cancer and other malignancies. Interestingly, a scientific study published in the journal Nature Reviews Clinical Oncology in late 2022 points to a significant increase in malignancies worldwide in people under 50 years old, and among the 14 types of cancer studied that are on the rise, even eight are related to the digestive system, which shows that diet, which affects the composition of the gut microbiome, has a significant effect on the risk of developing modern malignant diseases. Thanks to nutrigenetic tests, we now can detect the effects of ingested nutrients and other essential and non-essential food components on gene expression regulation. Genetic testing enables doctors and nutritionists to understand the interaction between genes and diet to identify dietary components that have beneficial or harmful effects on health and that can prevent the development of a large number of cancers and other malignancies.