Cancer is a disease of cells that grows and divides out of control, killing normal cells and spreading to other parts of the body. The cancer cells can grow into tumors that are often painful, disfiguring, and fatal. Cancer kills about 10 million people each year worldwide. Fortunately, thanks to advances in treatment and screening, more people survive cancer than ever before.
Cancer is caused by abnormal genes or chromosomes. Chromosomes are long chains of genes that act like instruction manuals for cells, telling them when to grow and when to die. Each time a cell grows or divides, the genetic information in a cell gets copied exactly into two new cells. If the DNA is damaged, either because of an injury or because of a mutation (changes in the genetic code), that cell may not follow its normal instructions and might not divide properly. Mutations may also cause a cell to start growing or dividing without stopping, even if the cell isn’t needed.
A genetic mutation may be a result of exposure to a carcinogen or a change in the environment. Some types of cancer can be passed on from generation to generation, while others occur randomly in a person’s lifetime. Scientists are learning more about how different environments and lifestyle choices affect a person’s chances of getting cancer.
In the past, doctors treated cancer by removing the tumors surgically or using other treatments such as chemotherapy or radiation therapy. These treatments can destroy cancer cells and keep them from growing or spreading.
When cancer spreads, it can also damage blood vessels and other organs, causing pain, loss of appetite, and other symptoms. Cancer also affects a person’s mental health, disrupting relationships with friends and family members.
As cancer spreads, it can also rob the body of the nutrients that help fight it. This can lead to a lack of energy, which is called cachexia. In addition, cancer can interfere with hormones that regulate growth and development.
Researchers are studying how to prevent cancer and how to treat it. One of the most important ways to avoid cancer is to get regular screening tests for common cancers such as cervical and colon cancers. These screening tests can find early-stage cancers when they are most treatable. Other ways to reduce your risk of developing cancer include avoiding tobacco and excessive sun exposure, eating fruits and vegetables, and getting enough sleep. If you’ve already been diagnosed with cancer, talk to your doctor about treatment options that are right for you. Radiation therapy uses high-energy rays (similar to x-rays) to kill cancer cells and shrink tumors. Other treatments include chemotherapy, which kills cancer cells and prevents them from growing, and immunotherapy, which helps your immune system fight cancer. Bone marrow transplants replace your blood-forming stem cells if they are destroyed by high doses of chemotherapy or radiation.