Cancer

Cancer medically called a malignant neoplasm, is a term for a large group of different diseases. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the body through the lymphatic system or bloodstream. Not all tumors are cancerous. Healthy cells control their own growth and will destroy themselves if they become unhealthy. Cell is a complex process that is normally tightly regulated. Cancer happens when problems in the genes in a cell prevent these controls from working. These problems with genes may be from damage to the gene or may be inherited. Damage to genes can come from many sources inside or outside of the cell.

 Determining what causes cancer is complex, and it is often impossible to assign a specific cause for a specific cancer. Many things are known to increase the risk of cancer including tobacco use, infection, radiation, lack of physical activity, poor diet and obesity, and environmental pollutants. These can directly damage genes or combine with existing genetic faults within cells to cause the disease. A small percentage of cancers, approximately five to ten percent, are entirely hereditary.

Cancer can be detected in a number of ways, including the presence of certain signs and symptoms, screening tests, or medical imaging. Once a possible cancer is detected it is diagnosed by microscopic examination of a tissue sample. Cancer is usually treated with chemotherapy, radiation therapy and surgery. The chances of surviving the disease vary greatly by the type and location of the cancer and the extent of disease at the start of treatment. While cancer can affect people of all ages, and a few types of cancer are more common in children, the risk of developing cancer generally increases with age. In 2007, cancer caused about 13% of all human deaths worldwide (7.9 million). Rates are rising as more people live to an old age and as mass lifestyle changes occur in the developing world.

 

Causes

It is almost always impossible to prove exactly what caused a cancer in any individual, because most cancers have multiple possible causes. For example, if a person who uses tobacco heavily develops lung cancer, then it was very probably caused by the tobacco use, but since everyone has a small chance of developing lung cancer as a result of air pollution or radiation, then there is a tiny chance that the smoker's lung cancer actually developed because of air pollution or radiation.

Cancers are primarily an environmental disease with 90-95% of cases attributed to environmental factors and 5-10% due to genetics. Environmental, as used by cancer researchers, means any cause that is not genetic, not merely pollution. Common environmental factors that contribute to cancer death include tobacco (25-30%), diet and obesity (30-35%), infections (15-20%), radiation (both ionizing and non-ionizing, up to 10%), stress, lack of physical activity, and environmental pollutants.

Medication

 

The concept that medications could be used to prevent cancer is an attractive one, and many high-quality clinical trials support the use of such chemoprevention in defined circumstances. Aspirin has been found to reduce the risk of death from cancer. Daily use of tamoxifen or raloxifene has been demonstrated to reduce the risk of developing breast cancer in high-risk women by about 50%.Finasteride has been shown to lower the risk of prostate cancer, though it seems to mostly prevent low-grade tumors.

 Vitamins have not been found to be effective at preventing cancer, although low levels of vitamin D are correlated with increased cancer risk. Whether this relationship is causal and vitamin D supplementation is protective is yet to be determined. Beta-carotene supplementation has been found to increase slightly, but not significantly, risks of lung cancer. Folic acid supplementation has not been found effective in preventing colon cancer and may increase colon polyps.

 

Vaccination

 

Vaccines have been developed that prevent some infection by some viruses that are associated with cancer, and therapeutic vaccines are in development to stimulate an immune response against cancer-specific epitomes. The hepatitis B vaccine prevents infection with hepatitis B virus and thus decreases the risk of liver cancer.

Advances in cancer research have made a vaccine designed to prevent cancers available. In 2006, the U.S. Food and Drug Administration(FDA) approved a human papilloma virus vaccine, called Gardasil. The vaccine protects against 6,11,16,18 strains of HPV, which together cause 70% of cervical cancers and 90% of genital warts. It also lists vaginal and vulvas cancers as being protected. In March 2007, the USCenters for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) officially recommended that females aged 11–12 receive the vaccine, and indicated that females as young as age 9 and as old as age 26 are also candidates for immunization. There is a second vaccine from Cervarix which protects against the more dangerous HPV 16,18 strains only. In 2009, Gardasil was approved for protection against genital warts. In 2010, the Gardasil vaccine was approved for protection against anal cancer for males.