Learn About Cancer
What is Cancer?
Cancer is defined as a cancerous tumour that has spread throughout the body.
Cancer is a condition in which some of the body's cells develop uncontrolled and spread to other areas of the body. It is the most common kind of cancer.
In the human body, which is composed of billions of cells, cancer may begin virtually anywhere in the body. Ordinarily, human cells develop and multiply (via a process known as cell division) in order to produce new cells when the body requires them. Cells die when they get too old or damaged to function properly, and new cells replace them.
In certain cases, this well-ordered mechanism is disrupted, resulting in aberrant or damaged cells growing and multiplying when they shouldn't. Tumors, which are masses of tissue, may develop from these cells. Tumors may be malignant or non-cancerous depending on their origin (benign).
Tumors that have progressed into or invaded surrounding tissues have the potential to move to distant locations in the body and generate new tumours (a process called metastasis). Malignant tumours are cancerous tumours that have spread throughout the body. Many malignancies, including leukemias, develop solid tumours; however, cancers of the blood, such as lymphomas, do not.
Benign tumours do not spread into or invade adjacent tissues and are thus classified as non-cancerous. When benign tumours are excised, they almost never recur, while malignant tumours may sometimes recur. However, benign tumours may grow to be very big in certain cases. Certain, such as benign tumours in the brain, may produce severe symptoms or even be life threatening in some cases.
The distinctions between cancer cells and normal cells are as follows:
Cancer cells are distinct from normal cells in a variety of ways. As an illustration, consider cancer cells:
They will continue to develop in the absence of signals instructing them to do so. Normal cells can only grow when they receive signals from the outside world.
Disregard signals that would usually warn cells to cease dividing or die (a process known as programmed cell death, or apoptosis).
infiltrate and spread to other parts of the body from their original location. Normal cells slow down their growth when they come into contact with other cells, and the majority of normal cells do not migrate throughout the body.
instructing blood vessels to develop in the direction of malignancies These blood veins provide oxygen and nutrition to tumours, as well as eliminate waste products from tumours, among other functions.
conceal oneself from the immunological system The immune system is responsible for eliminating damaged or abnormal cells in most cases.
Cancer cells are able to fool the immune system into assisting them in their survival and growth. For example, certain cancer cells are able to persuade immune cells to defend the tumour rather than destroying it.
acquire numerous alterations in their chromosomes, including as duplications and deletions of chromosomal sections, throughout the course of their lives Some cancer cells contain two times the number of chromosomes that are normally present.
Cells that are not typical cells depend on various types of nutrition. Furthermore, certain cancer cells generate energy from nutrients in a manner distinct from that of the majority of normal cells. Cancer cells are able to develop more rapidly as a result of this.
Cancer cells often depend so heavily on these aberrant activities that they are unable to survive if they are not there. Because of this, researchers have taken advantage of the situation, creating treatments that target the aberrant characteristics of cancerous cells. Some cancer treatments, for example, block blood vessels from developing toward tumours, thus depriving the tumour of vital nutrition.
What Causes Cancer to Develop?
On the other hand, cancer is a genetic illness, meaning that it is caused by mutations in genes that regulate the way our cells operate, particularly how they grow and divide.
Mutations in the DNA that cause cancer may arise as a result of mistakes that occur during cell division.
a kind of DNA damage produced by hazardous compounds in the environment, such as the chemicals found in cigarette smoke and UV radiation from the sun (More information may be found in our Cancer Causes and Prevention section.)
They were passed down to us from our parents.
Cells with damaged DNA are usually eliminated by the body before they develop into malignant tumours. However, as we get older, our bodies' capacity to do so diminishes. This is one of the factors that contributes to a greater chance of developing cancer later in life.
Each person's cancer is characterised by a distinct mix of genetic alterations. Additional alterations will occur as the disease continues to spread. Within a tumour, various cells may have distinct genetic alterations, even within the same tumour.
Genes that cause cancer are classified into many categories.
It has been discovered that the genetic alterations that lead to cancer impact three kinds of genes in particular: proto-oncogenes, tumour suppressor genes, and DNA repair genes. These modifications are referred to be cancer's "drivers" in certain circles.
Proto-oncogenes are genes that have a role in the normal development and division of cells. Cancer-causing genes (or oncogenes) are genes that enable cells to grow and survive when they should not. When these genes are changed in certain ways or become more active than normal, they may become cancer-causing genes (or oncogenes).
Tumor suppressor genes are also involved in the regulation of cell proliferation and division, in addition to tumour suppression. Cells that have specific mutations in tumour suppressor genes have the potential to divide in an uncontrolled manner.
DNA repair genes are responsible for the repair of damaged DNA. When these genes are mutated, cells with these mutations are more likely to acquire further mutations in other genes as well as chromosomal abnormalities such as duplications and deletions of chromosome regions. These mutations, when combined, have the potential to cause malignant cells to develop.
As scientists have gained a better understanding of the molecular alterations that lead to cancer, they have discovered that specific mutations are present in high frequency in a variety of cancers. There are a variety of cancer therapies available today that target gene alterations that have been identified in cancer. A number of these therapies can be taken by anybody who has cancer that contains the targeted mutation, regardless of where the disease first appeared or where it is now spreading.
When Cancer Extends Its Reach
Metastatic cancer is defined as cancer that has spread from the site where it originally developed to another part of the body after being diagnosed. Metastasis is the term used to describe the process by which cancer cells spread to different areas of the body.
A metastatic cancer has the same name as the original cancer and has the same kind of cancer cells as the original cancer (also known as primary cancer). For example, breast cancer that has spread to the lung and formed a metastatic tumour is referred to as metastatic breast cancer rather than lung cancer.
Under a microscope, metastatic cancer cells are almost identical in appearance to the cells that caused the initial disease. Furthermore, metastatic cancer cells and cells from the initial malignancy share a number of genetic characteristics, such as the presence of particular chromosomal alterations, that distinguish them from one another.
Some individuals with metastatic cancer may benefit from therapy, which may help them live longer lives. If the cancer has spread to another organ, the main aim of therapy is to slow its progression or to alleviate the symptoms that it is causing. Metastatic tumours may cause significant harm to the body's ability to function, and metastatic illness is the cause of death in the vast majority of cancer patients.
Changes in the tissue that are not cancerous
Not every alteration in the body's tissues indicates the presence of cancer. When left untreated, certain tissue alterations may progress to the point where they cause cancer. Here are some instances of tissue alterations that are not cancerous but are being watched in certain situations because they have the potential to become cancerous:
Hyperplasia is a condition in which cells within a tissue grow at a higher rate than usual, resulting in the accumulation of additional cells. Under a microscope, the cells and the way the tissue is structured, on the other hand, seem to be completely normal. Multiple causes or circumstances, including persistent inflammation, may contribute to the development of hyperplasia.
When compared to hyperplastic disease, dysplasia is a more advanced disease. There is also an accumulation of additional cells in the case of dysplasia. However, the cells have an irregular appearance, and there are alterations in the way the tissue is structured. In general, the more aberrant the cells and tissue seem, the higher the likelihood that cancer will develop. Some forms of dysplasia may need the monitoring or treatment of the patient, while others may not. A dysplastic nevus (also known as a dysplastic mole) is an abnormal mole that develops on the skin that is an example of dysplasia. A dysplastic nevus has the potential to develop into melanoma, but the majority do not.
Carcinoma in situ is a condition that is much more advanced than the previous one. Because the aberrant cells do not infiltrate surrounding tissue in the manner in which cancer cells do, even though it is often referred to as stage 0 cancer, it is not a form of cancer. However, since certain carcinomas in situ have the potential to progress to cancer, they are generally treated.
Cancer Facts and Figures
Cancer is defined as the uncontrolled proliferation of abnormal cells in any part of the body.
There are more than 200 different kinds of cancer.
Anything that has the ability to cause a normal body cell to grow abnormally has the potential to cause cancer; broad categories of cancer-related or causative agents include chemical or toxic substance exposures, ionising radiation, certain infections, and genetic factors in humans.
Cancer symptoms and signs vary depending on the particular kind and grade of cancer; nevertheless, the following may be seen in patients with various malignancies, despite the fact that general signs and symptoms are not highly specific: The following symptoms may occur: tiredness, loss of weight, discomfort, skin changes, altered bowel or bladder function, unusual bleeding, persistent coughing or changes in voice tone, fever, tumours, or tissue masses
Despite the fact that there are many tests available to screen for and presumptively diagnose cancer, the definitive diagnosis is established by examining a biopsy sample of probable cancer tissue in a laboratory setting.
Cancer staging is often established by biopsy findings, and it helps in determining the kind of cancer and the degree to which it has spread. It also aids caregivers in determining treatment regimens for their loved ones with cancer. In general, the higher the number assigned (which is typically between 0 and 4) in most staging systems, the more aggressive the cancer type or the more extensive the disease is in the body is considered. Staging techniques vary from cancer to cancer and must be addressed in detail with your health care practitioner on an individual basis before being used.
Treatment procedures differ depending on the kind and stage of cancer being treated. The majority of therapy regimens are tailored to the specific illness of each individual patient. However, the majority of cancer therapies involve at least one of the following, and in some cases, all of them: surgery, chemotherapy, and radiation therapy, to name a few.
There are many home remedies and alternative cancer therapies published on the internet, but patients are highly advised to examine them with their cancer physicians before implementing them.
The prognosis for cancer may vary from good to bad depending on the kind of disease. Because the prognosis varies depending on the kind of cancer and its staging, malignancies that are known to be aggressive and tumours that are staged with higher numbers (3 to 4) often have prognoses that are on the worse side.
In the United States, the three most frequent malignancies among men, women, and children are as follows:
Prostate, lung, and colorectal cancers in men
Breast, lung, and colorectal cancers are the most common cancers in women.
Children's leukaemia, brain tumours, and lymphoma are all possibilities.
What are the risk factors of cancer?
Everything that has the ability to cause a normal body cell to grow abnormally has the potential to create cancer. A variety of factors may result in cell abnormalities, some of which have been related to the development of cancer. Some cancers have no known origins, while others have environmental or lifestyle triggers, or may arise from a combination of known and unknown causes, such as smoking. Some characteristics may be affected by a person's genetic composition throughout their development. Many cancer patients acquire the disease as a result of a combination of these causes. Despite the fact that it is often difficult or impossible to determine the event(s) that caused cancer to develop in a specific person, research has provided clinicians with a number of likely causes that, either alone or in combination with other causes, are the most likely candidates for causing cancer to develop. The following is a list of main reasons, which is not exhaustive since new causes are being discovered on a regular basis as science progresses:
Tobacco or cigarette smoke (which includes at least 66 recognised probable carcinogenic compounds and toxins), benzene, asbestos, nickel, cadmium, vinyl chloride, benzidine, N-nitrosamines, aflatoxin, nickel and cadmium exposures.
Atomic radiation, which includes uranium, radioactive decay products of radioactive decay products of radioactive decay products of radioactive decay products of radioactive decay products of radioactive decay products of radioactive decay products of radioactive decay products
Infection with pathogens such as the human papillomavirus (HPV), Epstein-Barr virus (EBV), hepatitis B and C viruses, Kaposi's sarcoma-associated herpes virus (KSHV), Merkel cell polyomavirus (MCPV), Schistosoma species, and Helicobacter pylori; other bacteria are being investigated as potential agents. Pathogens:
Molecular Genetics: A variety of cancers, including breast and ovarian cancers as well as colorectal cancers and skin cancers have been linked to specific genes in humans.
In addition, it is essential to note that although almost everyone has risk factors for cancer and is exposed to cancer-causing chemicals (such as sunshine, secondhand cigarette smoke, and X-rays) throughout their lives, many people do not get cancer. Furthermore, many individuals carry genes that are related to cancer but do not acquire the disease as a result. Why? It is obvious that the more the quantity or degree of cancer-causing chemicals that a person is exposed to, and the greater the likelihood that the person would get cancer. However, researchers may not be able to provide an acceptable response for every individual. Furthermore, individuals who have genetic connections to cancer may be protected against developing it for the same reasons (lack of enough stimulus to make the genes function). Aside from that, some individuals may experience an amplification of their immune response, which allows them to manage or destroy cells that are or may become cancerous. There is evidence to suggest that even particular dietary habits, when combined with the immune system, may have a major influence in determining whether cancer cells survive or are killed. Consequently, it is difficult to attribute a particular aetiology of cancer to many people for these reasons.
Other risk factors have also been added to the list of things that may raise the likelihood of developing cancer. In particular, red meat (such as beef, lamb, and pork) has been classified as a high-risk agent for the development of cancer by the International Agency for Research on Cancer; in addition, processed meats (such as salted, smoked, preserved, and/or cured meats) have been classified as carcinogenic agents by the World Health Organization. Because of the chemicals produced when meat is cooked at high temperatures, those who consume a lot of barbecued meat may be at increased risk. Weight gain, lack of physical activity, chronic inflammation, and hormones, particularly those used for replacement treatment, are all examples of less well-defined factors that may raise the risk of certain malignancies in some people. Other products, like as mobile phones, have been subjected to extensive research. Cell phone low-energy radiation was categorised as "possibly carcinogenic," by the World Health Organization in 2011, although this is a very low-risk threshold that puts cell phones at the same risk as coffee and pickled vegetables, according to the organisation.
It is difficult to demonstrate that a drug does not cause or is not associated with an elevated cancer risk. For example, some scientists believe that antiperspirants may be associated with breast cancer, whereas others do not believe this to be the case. The National Cancer Institute's stated position is that "additional research is needed to investigate this relationship and other factors that may be involved." This unsatisfactory conclusion is given as a result of the conflicting nature of the evidence gathered so far. Other claims that are comparable to this one would require extensive and costly study that may never be completed. It may be reasonable to advise people to avoid excessive quantities of any chemicals that are even slightly associated with cancer, but this may be difficult to accomplish in complex, technologically sophisticated contemporary cultures.
The signs and symptoms of cancer will vary depending on which region of the body is affected and how advanced the disease is.
Here are some examples of common signs and symptoms that are linked with, but not unique to cancer:
The presence of a lump or a thickening that may be felt under the skin
Weight fluctuations, including unexpected loss or gain, are common.
Skin changes, such as yellowing, darkening, or redness of the skin, wounds that won't heal, or alterations to existing moles, are all signs of a problem with the immune system.
Constipation or bladder habits that have changed
Coughing or breathing difficulties on a regular basis
Having trouble swallowing
After eating, you may have persistent indigestion or pain.
Muscle or joint pain that is persistent and inexplicable
Fever or nocturnal sweats that are persistent and unexplained
Unexpected bleeding or bruising that does not seem to be related to an injury.