What Is Cancer?

L.L. Woodard, Contributing writer

Cancer can be a frightening diagnosis. Information and research, in addition to that provided by the physician and health care team, can help to alleviate some of that fear and empower a patient to move beyond the diagnosis.

The National Cancer Institute, the National Institutes of Health and the Mayo Clinic define cancer as any of more than 100 diseases that are characterized by abnormal cells that divide without control and are able to invade other tissues, spreading throughout the body via the blood and lymph system.

The cells generally grow into a lump -- though not in blood cancers -- that form a tumor, according to the Cleveland Clinic. The tumors will be one of two types: benign, which is noncancerous or self-contained; or malignant, which is cancerous and able to spread.

How Many Cancer Types?

There are more than 100 different types of cancer, the National Cancer Institute says, most of them named for their sites of origin, such as pancreatic cancer or colon cancer.

Cancer as a whole is the second leading cause of death in the U.S.

But several types of cancer have become less deadly in recent years due to the development improved treatments and an increase in early detection. The National Cancer Institute reported that, for the first time since 1998, "both incidence and death rates for all cancers combined are decreasing for both men and women."

The severity of a particular cancer can vary greatly, depending on how early it is detected and the site of origin. However cures remain elusive.

Improved Understanding of Cancer Types

The National Cancer Institute divides cancer into five broad categories:

• Carcinomas: Start in the skin or tissues that line or cover internal organs
• Sarcomas: Start in bones, cartilage, fat, muscle, blood vessels or other connective and supportive tissue
• Leukemias: Begin in the bone marrow and cause large numbers of abnormal blood cells to be produced and enter the blood
• Lymphomas and myelomas: Appear in the cells of the immune system.
• Central nervous system cancers: The tissues of the brain and spinal cord are affected

Cancer Symptoms

The National Cancer Institute says the most common cancers n the U.S. are bladder cancer, breast cacner, colorectal cancer, endometrial cancer, kidney cancer, leukemia, lung cancer, melanoma, non-Hodkins lumphoma, pancreatic cancer, prostate cacner, nonmelanoma skin cancer and thyroid cancer.

The symptoms of cancer can often mean other, less serious diseases, but they should be reviewed by a doctor, according to the Cleveland Clinic.

They include sores that don't heal, changes in a wart or mole, unusual lumps, persisten cough, indigestion, problems swallowing and changes in bowl movements.

An unusual loss of weight or bleeding can also be signs of cancer.

Cancer does not have to be a death sentence. It is important that it be diagnosed in the earliest stages for the best success rate in treatment. Heeding the warning signs of cancer is in a person's best interest for long-term good health.