Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues. Cancer cells can spread to other parts of the body through the blood and lymph systems. Cancer is not just one disease but many. There are more than 100 different types of cancer. Most cancers are named for the organ or type of cell in which they start. For example, cancer that begins in the colon is called colon cancer. Cancer that begins in melanocytes of the skin is called melanoma. Cancer types can be grouped into broader categories, including:
- Carcinoma: Cancer that begins in the skin or in tissues that line or cover internal organs. There are a number of subtypes of carcinoma, including adenocarcinoma, basal cell carcinoma, squamous cell carcinoma, and transitional cell carcinoma.
- Sarcoma: Cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.
- Leukemia: Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood.
- Lymphoma and myeloma: Cancers that begin in the cells of the immune system.
- Central nervous system cancers: Cancers that begin in the tissues of the brain and spinal cord.
The most common type of cancer is prostate cancer, with more than 238,000 new cases expected in the U.S. in 2013. The next most common cancers are breast cancer and lung cancer. For 2013, the estimated number of new cases of colon cancer and rectal cancer add to a total of 142,820 new cases of colorectal cancer. Kidney cancers can be divided into two major groups, renal parenchyma and renal pelvis. Approximately 92% of kidney cancers develop in the renal parenchyma, and nearly all of these cancers are renal cell cancers. The estimated number of new cases of renal cell cancer for 2013 is 59,938.
Signs and Symptoms: The general signs and symptoms of cancer does not necessarily indicate having it; many other things can also cause similar signs and symptoms. If these signs or symptoms last for a long time or get worse, consult your physician.
- An unexplained weight loss of 10 pounds or more may be the first sign of cancer. This happens most often with cancers of the pancreas, stomach, esophagus (swallowing tube), or lung.
- Fever is very common with cancer, but it more often happens after cancer has spread from where it started. Almost all patients with cancer will have fever at some time, especially if the cancer or its treatment affects the immune system.
- Fatigue or extreme tiredness that does not get better with rest. It may happen early in some cancers, like leukemia.
- Pain may be an early symptom with some cancers like bone cancers or testicular cancer. A headache that does not go away or get better with treatment may be a symptom of a brain tumor. Back pain can be a symptom of cancer of the colon, rectum, or ovary.
- Along with cancers of the skin, some other cancers can cause skin changes that can be seen.