ONCOLOGY
Basic facts about a cancer”
Description of Cancer
Cancer is a disease characterized by the uncontrollable multiplication and proliferation of body cells.
Cancer can begin almost anywhere in the trillions of cells that make up the human body. Normal human cells divide and proliferate (a process known as cell division) to generate new cells as the body requires them. When cells age or become damaged, they perish and are replaced by new cells.
Occasionally, this orderly process breaks down, and abnormal or damaged cells proliferate and propagate inappropriately. These cells are capable of forming tumors, which are tissue masses. Tumors may be malignant or non-malignant (benign).
The process by which cancerous tumors travel to distant parts of the body and create new tumors is referred to as metastasis. Cancerous tumors can also invade nearby tissues. Malignant tumors are another name for cancerous tumors. Blood malignancies, including leukemias, typically do not form solid tumors.
Benign tumours do not invade or disseminate to adjacent tissues. When excised, benign tumors typically do not regrow, whereas malignant tumors occasionally do. However, benign tumors can occasionally be quite large. Some tumors, such as benign brain tumors, can cause severe symptoms or be life-threatening.
Differences between Cancer Cells and Normal Cells
Normal cells differ from cancer cells in several ways. As an example, malignant cells:
grow in the absence of growth-promoting signals. Normal cells only proliferate in response to such signals.
Ignore signals that ordinarily instruct cells to cease dividing or to perish (a process known as programmed cell death, or apoptosis).
Invade neighboring areas and propagate to other body parts. Normal cells cease to proliferate when they come into contact with other cells, and the majority of normal cells do not migrate.
instruct blood vessels to develop into tumors. These blood vessels provide oxygen and nutrients to tumors and remove debris from tumors.
avoid the immune system. Typically, the immune system eliminates damaged or abnormal cells.
To deceive the immune system into aiding cancer cell survival and growth. Some cancer cells, for instance, can persuade immune cells to protect the tumor rather than attack it.
Multiple chromosomal alterations, such as duplications and deletions, occur in these organisms. Some cancer cells have twice as many chromosomes as normal cells.
cancer cells require different nutrients than normal cells. In addition, some cancer cells produce energy from nutrients differently than the vast majority of healthy cells. This allows cancer cells to multiply more rapidly.
Often, cancer cells are dependent on these anomalous behaviors to the point that they cannot survive without them. Utilizing this truth, researchers have developed therapies that target the abnormal characteristics of cancer cells. Some cancer therapies, for instance, inhibit blood vessels from growing toward tumors, starving the tumor of essential nutrients.
How Does Cancer Develop?
Cancer is a genetic disease, meaning that it is caused by alterations to the genes that regulate the way our cells function, particularly their growth and division.
Cancer-causing genetic alterations can occur because of slipups that occur during cell division, DNA damage caused by hazardous environmental substances, such as the chemicals in tobacco smoke and the sun’s ultraviolet rays. Our Cancer Causes and Prevention section contains additional details.
They were passed down to us from our ancestors.
Typically, the body eliminates DNA-damaged cells before they become malignant. However, the body’s capacity to do so declines with age. This contributes to the increased risk of developing cancer later in life.
Each individual’s malignancy has a distinct combination of genetic alterations. As the malignancy continues to spread, further alterations will occur. Even within a single tumor, various cells may undergo distinct genetic alterations.
Types of cancer-causing genes
The genetic alterations that contribute to cancer typically affect three major classes of genes: proto-oncogenes, tumor suppressor genes, and DNA repair genes. These alterations are sometimes referred to as „drivers“ of cancer.
Proto-oncogenes play a role in normal cell division and growth. However, when these genes are altered in certain ways or are more active than usual, they can transform into cancer-causing genes (or oncogenes), allowing cells to grow and survive when they should not.
Additionally, tumor suppressor genes regulate cell proliferation and division. Certain mutations in tumor suppressor genes may cause uncontrolled cell division.
DNA repair genes are involved in repairing damaged DNA. There is a tendency for cells with mutations in these genes to develop additional mutations in other genes and chromosomal alterations, such as duplications and deletions. Together, these mutations may result in the development of malignant cells.
As scientists have gained a deeper understanding of the molecular changes that contribute to cancer, they have discovered that certain mutations are prevalent in numerous cancer types. There are currently numerous cancer treatments that target cancer-associated gene mutations. Several of these treatments are available to anyone with a cancer that has the targeted mutation, regardless of where the cancer originated.
When Cancer Spreads
Metastatic cancer is cancer that has spread from the site where it originated to another part of the body. Metastasis is the process by which cancer cells spread to other regions of the body.
The cells of metastatic cancer are identical to those of the original, or primary, cancer. For instance, breast cancer that spreads to the lung is considered metastatic breast cancer, not lung cancer.
Under a microscope, metastatic cancer cells resemble the original cancer cells in appearance. In addition, metastatic cancer cells and the original cancer cells typically share certain molecular characteristics, such as the presence of specific chromosomal alterations.
In some instances, treatment may help people with metastatic cancer survive longer. In other instances, the primary objective of treatment for metastatic cancer is to control the cancer’s growth or alleviate its symptoms. Metastatic tumors can cause severe injury to the body’s functions, and metastatic disease accounts for the majority of cancer-related deaths.
Sequencing
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