Cancer is a disease in which abnormal cells divide uncontrollably and destroy body tissue or spread to other parts of the body. Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and multiply to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place. Sometimes this orderly process breaks down, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumors, which are lumps of tissue. Tumors can be cancerous or not cancerous.

Causes of cancer

  • Chemical

1. Tobacco The mechanism of action of two of them, acrylonitrile and acrolein, appears to involve oxidative stress and oxidative DNA damage. The other five toxicants, acetaldehyde, cadmium, ethylene oxide, formaldehyde and isoprene act through various mechanisms including direct interaction with DNA. Tobacco smoke contains over fifty known carcinogens, including nitrosamines and polycyclic aromatic hydrocarbons. Tobacco is responsible for about one in three of all cancer deaths in the developed world, and about one in five worldwide. 2. Materials Some substances cause cancer primarily through their physical, rather than chemical, effects on cells. A prominent example of this is prolonged exposure to asbestos, naturally occurring mineral fibers which are a major cause of mesothelioma, which is a cancer of the serous membrane, usually the serous membrane surrounding the lungs.

  • Lifestyle

1. The World Health Organization has classified alcohol as a Group 1 carcinogen. In Western Europe 10% of cancers in males and 3% of cancers in females are attributed to alcohol. Worldwide, 3.6% of all cancer cases and 3.5% of cancer deaths are attributable to alcohol. 2. Some specific foods have been linked to specific cancers. Studies have shown that individuals that eat red or processed meat have a higher risk of developing breast cancer, prostate cancer, and pancreatic cancer. Several risk factors for the development of colorectal cancer include high intake of fat, alcohol, red and processed meats, obesity, and lack of physical exercise. 3. Every year, nearly 85,000 new cancer diagnoses in the United States are related to obesity. There is an association between obesity and colon cancer, post-menopausal breast cancer, endometrial cancer, kidney cancer, and esophageal cancer.[54] Obesity has also been linked with the development of liver cancer.

  • Hormones

Some hormones play a role in the development of cancer by promoting cell proliferation.[58] Insulin-like growth factors and their binding proteins play a key role in cancer cell growth, differentiation and apoptosis, suggesting possible involvement in carcinogenesis. Hormones are important agents in sex-related cancers such as cancer of the breast, endometrium, prostate, ovary, and testis, and also of thyroid cancer and bone cancer.

  • Infection

Viruses are the usual infectious agents that cause cancer but bacteria and parasites also contribute. Infectious organisms that increase the risk of cancer are frequently a source of DNA damage or genomic instability.

  • Radiation

Up to 10% of invasive cancers are related to radiation exposure, including both 1. Non-ionizing radiation 2. Ionizing radiation Unlike chemical or physical triggers for cancer, ionizing radiation hits molecules within cells randomly. If it happens to strike a chromosome, it can break the chromosome, result in an abnormal number of chromosomes, inactivate one or more genes in the part of the chromosome that it hit, delete parts of the DNA sequence, cause chromosome translocations, or cause other types of chromosome abnormalities. Major damage normally results in the cell dying, but smaller damage may leave a stable, partly functional cell that may be capable of proliferating and developing into cancer, especially if tumor suppressor genes were damaged by the radiation.

  • Rare causes

1. Organ transplantation The development of donor-derived tumors from organ transplants is exceedingly rare. The main cause of organ transplant associated tumors seems to be malignant melanoma, that was undetected at the time of organ harvest. 2. Trauma Physical trauma resulting in cancer is relatively rare. Claims that breaking bones resulted in bone cancer, for example, have never been proven. Similarly, physical trauma is not accepted as a cause for cervical cancer, breast cancer, or brain cancer.

Complications of cancer

  • Malnourishment

Malnutrition is a major cause of mortality in advanced cancer. This can happen when tumors in the digestive system form a blockage or interfere with the absorption of essential nutrients. Signs of malnutrition include: loss of lean body mass muscle wasting fatigue cognitive difficulties weakened immune system

  • Lack of oxygen

Tumors in the lungs can block part of the lung or cause it to collapse. A diseased or collapsed lung can lead to: a lung infection that’s difficult to treat the inability to absorb enough oxygen trouble breathing

  • Liver damage

The liver has many important jobs — such as filtering toxins from the blood and maintaining the balance of chemicals. Liver tumors can prevent the liver from performing these functions, which can lead to jaundice and other life threatening issues. Signs that your liver isn’t working well include: 1. Yellowing of the eyes and skin 2. Abdominal swelling or bloating 3. Dark-colored urine 4. Loss of appetite 5. Nausea 6. Weight loss

  • Too much calcium

Cancer in the bones can cause too much calcium (hypercalcemia) to be released into the bloodstream. This can affect the proper functioning of the heart, kidneys, and muscles. It can also cause neurological symptoms, such as confusion, memory loss, and depression. High calcium levels can lead to coma or death.

  • Problems with blood and blood vessels

Cancers that push into blood vessels can cause serious damage. In the brain, this can lead to a stroke. Cancer that affects bone marrow can interfere with the production of: 1. Red blood cells, which carry oxygen throughout the body 2. Platelets, which are needed to stop bleeding 3. White blood cells, which are needed to fight infection

  • Infection

Several factors can raise the risk of developing serious infections, such as: 1. Malnutrition 2. Lack of white blood cells 3. Tumors in the lungs that make it hard to fight any type of pneumonia

Types of cancer

  • Carcinoma

This cancer begins in the skin or in tissues that line or cover internal organs. There are different subtypes, including adenocarcinoma, basal cell carcinoma, squamous cell carcinoma and transitional cell carcinoma.

  • Sarcoma

This cancer begins in the connective or supportive tissues such as bone, cartilage, fat, muscle or blood vessels.

  • Leukaemia

This is cancer of the white blood cells. It starts in the tissues that make blood cells such as the bone marrow.

  • Lymphoma and Myeloma

These cancers begin in the cells of the immune system.

  • Brain and Spinal cord cancers

These are known as central nervous system cancers.

How is cancer stage determined?

  • Healthcare providers use cancer staging systems to plan treatment and develop a prognosis or expected outcome. TNM is the most widely used cancer staging system. T stands for primary tumor. N stands for lymph nodes and indicates whether a tumor has spread to your lymph nodes. M stands for metastasis, when cancer spreads.

How Does Cancer Develop?

  • Cancer is a genetic disease—that is, it is caused by changes to genes that control the way our cells function, especially how they grow and divide. Genetic changes that cause cancer can happen because: of errors that occur as cells divide. of damage to DNA caused by harmful substances in the environment, such as the chemicals in tobacco smoke and ultraviolet rays from the sun. (Our Cancer Causes and Prevention section has more information.) they were inherited from our parents. The body normally eliminates cells with damaged DNA before they turn cancerous. But the body’s ability to do so goes down as we age. This is part of the reason why there is a higher risk of cancer later in life. Each person’s cancer has a unique combination of genetic changes. As the cancer continues to grow, additional changes will occur. Even within the same tumor, different cells may have different genetic changes.

Sign and Symptoms

  • Unexplained weight loss
  • Chronic tiredness
  • Persistent pain
  • Fever that occurs mostly at night
  • Skin changes, particularly moles that change shape and size or new moles
  • Bruising or bleeding more easily
  • Lumps or bumps under your skin that don’t go away
  • Difficulty breathing
  • Difficulty swallowing
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