When you feel a prolonged burning sensation in your throat or chest, don’t assume it’s just indigestion. It could be esophageal or lung cancer, respectively. A persistent cough that doesn’t go away, or that is accompanied by hoarseness or shortness of breath, can also be a sign of lung cancer. Other warning signs include lumps, abnormal bleeding and a loss of appetite.
Cancer is a disease that develops when cells in your body start to grow out of control. It happens when genes that manage cell activity mutate. Mutations may be caused by things you do, or they may occur randomly. Some types of cancer are caused by viruses. Others are caused by exposure to certain substances, including sunlight, tobacco and certain drugs or infections with the human papillomavirus (HPV).
Cells are made of protein and other molecules that form tissues and organs in your body. The cells that make up your skin, for example, are called epithelial cells. Cancer can form in any type of epithelial cell. Cancer can also begin in other cells that line tissues, such as blood vessels and lungs. It can even begin in cells that make up bone, such as bone marrow cells. Cancer can also spread from one area to another, or to other parts of the body. This is called metastasis.
The way doctors classify cancer depends on where it starts, how quickly it grows and whether it has spread. There are more than 100 different kinds of cancer. Some are more serious than others. The survival rates of people with various types of cancer vary a great deal, and depend on the stage of the cancer, whether it has spread, and other factors.
Many of the things that can cause cancer are preventable. For instance, cigarette smoking, excess weight and drinking alcohol are risk factors for cancer. So is exposure to ultraviolet radiation from the sun and tanning beds. In addition, it is important to eat a well-balanced diet and be physically active.
In addition to lifestyle choices, some cancers are caused by genetic predisposition and other factors that are out of a person’s control. For example, many people who move to other countries develop cancers common in their adopted country, rather than the types of cancer they had in their homelands.
Until recently, most of the causes of cancer were not known. The earliest epidemiological studies indicated that high rates of cancer occurred in specific occupations. These early studies included Bernardino Ramazzini’s report in 1713 that nuns had high rates of breast cancer, and Percivol Pott’s report in 1875 that chimney sweeps had high rates of scrotal cancer. Later, research found that some chemicals, such as asbestos, arsenic and radiation, can cause cancer in humans. Research also showed that some diseases, such as HIV/AIDS and hepatitis B or C, can also be causes of cancer. There is now sufficient evidence that some bacteria, fungi, salted fish, herbs and wood dust can also be carcinogenic in humans.