Other genetic diseases: cancer
Cancer in society
The word Cancer It is a term used to define a group of very common diseases worldwide that cause the death of a large number of people. WHO It is estimated that during 2020, almost 10 million people died worldwide from cancer, with lung cancer being the type that caused the most deaths. In Spain, during 2020, according to the According to the Spanish Cancer Association , 281,478 cases of cancer were reported, with the highest incidence in men. This is due to:
- Genetic causes : recently some scientists They have shown that aging causes the loss of 6 essential genes on the Y chromosome associated with various cell cycle functions.
- Lifestyle habits : Men generally have greater exposure to environmental factors that can trigger cancer, and women tend to take better care of themselves and be more concerned about their health. For example, men tend to smoke more, drink more, and have greater sun exposure due to not using sunscreen. All of this can cause alterations in epigenetics. cells that trigger cancer.
1. Epigenetics : Changes in the function of certain genes that can be activated or inhibited by various causes, such as environmental factors or aging. These changes in function do not cause changes in the genetic structure of DNA.
What is cancer? Why does it occur?
Cancer originates from the proliferation of uncontrolled cell masses that cause the formation of tumors, in a process called carcinogenesis . There are two types of tumors:
- Malignant tumors: These are cell masses that grow uncontrollably and have the ability to rapidly invade other tissues. Furthermore, when removed by surgery, they have a high probability of regrowth.
- Benign tumors: These are cell masses that also grow uncontrollably but are not highly likely to metastasize; they are localized exclusively to a single tissue or organ. Furthermore, when they are removed by surgery, they typically do not regrow.
The former can invade other tissues and organs of the body through metastasis. This process begins when a tumor cell enters a blood or lymphatic vessel and travels to another target organ where it settles and proliferates. Tumor cells can enter blood vessels by molecular changes of the cells that promote their ability to enter, by structural changes of the blood vessels that facilitate the entry of the tumor cell or because the tumor cells form their own blood vessels in the microenvironment in which they are found. When this occurs, under normal health conditions, the immune system's T cells recognize tumors and eliminate them. However, occasionally, tumor cells are able to evade the molecular recognition processes used by T cells, causing tumor proliferation and the development of metastasis. Tumor cells are also known to have preferences for certain target organs, but the exact cause is still unknown. This may be due to the size of the capillaries that facilitate the cell's arrival at certain organs or due to active processes generated by interaction with molecular biomarkers.
The role of genetics in cancer
Genetic mutations that cause cancer develop in three types of genes: proto-oncogenes, tumor suppressor genes, and DNA repair genes.
- Proto-oncogenes : These genes control cell division. However, if mutations occur in them, they become oncogenes and do not prevent cell division when the process is no longer necessary. Thus, oncogenes promote the accumulation of these cells in the body and trigger the development of tumors. Mutations that appear in proto-oncogenes are usually dominant; that is, with a single mutated copy of the gene, the oncogene is generated.
- Tumor suppressor genes : These are genes found in all our cells and are responsible for preventing the development of tumors by preventing massive cell growth. They control apoptosis . and cellular repair, and if they mutate, both functions are affected.
- DNA repair genes : There are approximately 153 genes responsible for repairing DNA during cell division. Mutations in these genes generate nonfunctional proteins that severely disrupt cellular functions.
2. Apoptosis: programmed cell death of cells that are no longer performing their function correctly or that may be harmful to the body.
Physiology and characteristics of the tumor
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In the solid mass of cells that make up a tumor, the accumulation of mutations causes genomic instability in the different cells that comprise it. Typically, the tumor settles on the cellular matrix, formed by a basal lamina that is degraded and transformed by the tumor itself, which facilitates the production of certain growth factors that promote the proliferation of the cells it contains. In parallel with cell proliferation, angiogenesis , a process by which blood vessels surround the tumor to transport nutrients and oxygen to the surface cells, since conditions of hypoxia (lack of oxygen) occur inside the tumor.
Factors that determine the appearance of cancer
Hereditary factors
Mutations that have caused cancer in parents can be passed on to their children, making them more susceptible to the disease. However, hereditary factors represent between 5 and 10% of all cancer cases, so they are not the main risk factor. Even so, through the genetic studies and thorough check-ups of the offspring of people who have suffered from cancer can prevent the development of the disease.
Between 70 and 80% of cancers are caused by environmental factors or harmful substances incorporated into our lifestyles, such as tobacco, excessive sun exposure, urban pollution, consumption of burnt foods containing benzopyrenes (a carcinogenic chemical), obesity, and sedentary lifestyles, among others. Therefore, special attention must be paid to these types of factors, both because of their abundance and their close link to the onset of this disease.
Can I know if I will get cancer?
Although this answer cannot be known 100%, it is true that hereditary factors can be controlled through genetic studies of the descendants of people who have suffered from cancer, thus preventing the development of the disease. Furthermore, thanks to the results of these types of tests, we can avoid bad habits that promote the development of cancer and adapt those that are healthy for our bodies.
Although genetics is not the most relevant factor in the development of cancer, knowledge of this helps to reduce the impact of environmental factors on an individual's health. Therefore, by using the hundreds of genetic testing that oncological genetics puts at our disposal, we can further protect ourselves from one of the diseases with the worst prognosis today.