Unfortunately, many types of cancer don't display any obvious symptoms or cause pain until well advanced.  Because early-stage cancer symptoms tend to be subtle, they are often mistaken for signs of other, less-threatening diseases. Here are the seven warning signs of cancer:

• Changes in bowel or bladder habits
• A sore that does not heal
• Unusual bleeding or discharge
• Thickening or lump in the breast or any other part of the body
• Indigestion or difficulty swallowing
• An obvious change in a wart or mole
• A nagging cough or hoarseness

Some symptoms are specific to certain types of cancer, such as difficult urination for prostate cancer, or flu-like symptoms for acute leukemias. Don't be afraid to discuss unusual symptoms with your doctor!  Diagnostic tests are available for most common cancers. If diagnosed early, your chances of surviving cancer are greatly increased.

There are many different types of cancer.  Several factors, including location and how the cancerous cells appear under the microscope, determine how cancer is diagnosed.  For example, there are several forms of breast cancer, classified according to where the tumors originate within the breast, and their tendency to invade surrounding organs and tissue. All cancers, however, fall into one of four broad categories:

Carcinomas are tumors that arise in the tissues that line the body's organs. About 80% of all cancer cases are carcinomas.

Sarcomas are tumors that originate in bone, muscle, cartilage, fibrous tissue or fat.

Leukemias are cancers of the blood or blood-forming organs.

Lymphomas affect the lymphatic system, a network of vessels and nodes that acts as the body's filter. The lymphatic system distributes nutrients to blood and tissue, and prevents bacteria and other foreign "invaders" from entering the bloodstream.   There are over 20 types of lymphoma.