The exact cause of cancer is not known, but various factors are likely at play. Although genetic factors have been linked to certain types of cancers, less than 5% of cancers are associated with known inherited gene mutations. For example, two genes known to be associated with breast cancer are BRCA1 and BRCA2, but less than 5% of breast cancers are associated with these genes. Most forms of cancer are due to genetic mutations of cells that occur within a person's life as a result of environmental factors such as cigarette smoke or exposure to radiation. Exposure to the following environmental factors can cause cancer:

• tobacco smoking: Smoking causes lung cancer and is also associated with an increased risk for cancers of the mouth (oral cancers), larynx, esophagus, bladder, and cervix.
• chemicals: Exposure to industrial dyes, asbestos, and benzene is linked to cancer.
• ionizing radiation: A connection between ionizing radiation and cancer has been made, but the exact amount of radiation exposure that increases the risk of cancer is not known.
• viruses: Certain viruses, such as the human immunodeficiency virus (HIV, which causes AIDS) are associated with an increased risk of liver cancer, lymphomas, and sarcomas. The human papillomavirus (HPV, which causes venereal warts) is associated with an increased risk of oral, anal, and cervical cancer.
• sunlight: Prolonged exposure (e.g., sun tanning) causes skin damage and may result in skin cancer.

Cancer can cause many different types of symptoms depending on the type of cancer and what stage it's in. Cancer cells pressing on or invading surrounding cells can cause severe pain. Organs (like the liver or pancreas) that are being invaded by the cancer can't work properly. Some symptoms, called paraneoplastic syndromes, are caused not by the tumour itself but by chemicals or hormones produced by the tumour. The chemicals and hormones can cause an autoimmune reaction where the body produces antibodies against itself. They can also affect the normal functioning of organs or even kill healthy cells.

Some of the complications of cancer can be life-threatening. Cancer can cause fluid to fill the sacs surrounding the heart or lung, making it very hard to breathe. Cancer can also block the veins that return blood from the upper parts of the body to the heart. This causes the veins in the chest and neck to swell. Cancer can also press on the spinal cord or spinal cord nerves, causing pain or the loss of function of the nerve. The longer a nerve has been damaged, the less likely it will recover. Hypercalcemic (high calcium) syndrome occurs either when a cancer produces a hormone that dangerously raises the body's calcium levels or when cancer extensively invades the bones.

Cancer specialists called oncologists will evaluate symptoms, perform a physical examination, and order blood tests and X-rays. The only way to tell for sure whether cells are cancerous, however, is to take a tissue sample, called a biopsy. The cells are looked at under a microscope. Doctors can tell the type and stage of cancer based on the biopsy sample.

At the time of diagnosis, staging of the cancer is done to help determine the prognosis and type of treatment a patient should receive. Doctors basically classify the cancer according to a staging system called the "TNM system," which describes the size of the tumour and the extent of cancer spread. The choice of treatment will largely depend on the stage of the cancer.

Certain types of cancers can be prevented through lifestyle modifications – this is known as primary cancer prevention. Tobacco-related cancers (e.g., lung cancer) account for almost one-third of all fatal types of cancer; therefore, quitting smoking is key for preventing cancers of the mouth, throat, esophagus, and lungs. Avoiding and limiting sun exposure, and using adequate protection (SPF lotions and sunscreens) while in the sun, will reduce the risk for developing skin cancer. Diet is another important area for cancer prevention. A high-fat diet is associated with a higher risk for certain cancers (such as breast and prostate), while a high-fibre diet has long been thought to reduce the risk for colon cancer.

Surgery, radiation, chemotherapy, and, for some cancers, hormones or hormone-blocking medications are all used to treat cancer. The goal of cancer treatment is to kill cancerous cells while killing as few healthy cells as possible in the process.

Surgery is used to remove cancer cells that are packed together. Many cancers are treated with surgery. Surgeons will also remove normal cells around the cancerous cells or tumour to determine if the cancer has spread or not. Once the cancer has spread, it's very difficult to remove cancer cells with surgery.

Radiation is used to treat localized cancers. Radiation therapy can take a number of different forms. A beam of radiation can be aimed onto the skin near the site of the cancer. The radiation kills the cancer cells. Unfortunately, it also kills healthy cells. Newer radiation machines are getting better at focusing the radiation only on the cancerous cells, and not the normal cells. Radioactive particles can also be injected into the blood. The particles stick to cancerous cells, but not to normal cells. Sometimes, small radioactive particles are placed right into an organ next to the cancer, giving the cancerous cells a much higher dose of radiation than the normal cells.

Chemotherapy is treatment that uses anticancer medications. It's often used when the cancer has spread throughout several areas of the body. For many cancers, a combination of medications is used because it works better than just one medication. A complete response to chemotherapy is when all detectable cancer has disappeared. However, some cancer cells may still remain in the body and are undetected. As a result, the cancer may grow back after a period of remission. A partial response is when the cancer shrinks by 30% or more. Unfortunately, many cancers become immune to the anti-cancer medications over time. There are certain types of cancers (e.g., breast cancer) that are influenced by hormones; they can be treated with hormones or hormone-blocking medications to slow their growth.

Genetic engineering is being used to control the genes that turn cancer growth on and off and to control the enzymes that allow cancer cells to continually divide and grow. Cancer vaccines, antibodies combined with poisons, and chemicals that turn off blood vessel growth in cancers, are some of the newer developments being investigated in the battle against cancer.

All material copyright MediResource Inc. 1996 – 2022. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/condition/getcondition/Cancer