Cancer

Cancer is a complex group of over 100 diseases. Cancer is an uncontrolled spreading of malignant cells in the human body.

Cells normally divide and grow in an organized manner. Cancer occurs when cells grow in an uncontrolled manner and  form a mass called either a tumor or a lesion.

A cancerous tumor is called a malignant tumor. Malignant tumors can spread to surrounding tissue. These cells can break loose from the tumor and travel in the bloodstream to other parts of the body, where new tumors may form. This is called metastasis. This new tumor has cells identical to those of the original tumor.

A benign tumor is not cancerous and often can be removed with surgery and do not usually come back. Benign tumors do not metastasize.

Bone cancer The most common type of bone cancer is osteosarcoma, which develops in new tissue in growing bones. Osteosarcoma, also called osteogenic sarcoma, is a cancer of the bone that usually affects the large bones of the arm or leg. It affects young people more than old and more males than females. Another type of cancer, chondrosarcoma, develops in cartilage. Osteosarcoma and Ewing's sarcoma (another type of bone cancer) tend to occur more frequently in children and adolescents, while chondrosarcoma occurs more often in adults.

Note that a cancer which begins in the bone (primary bone cancer) is a different disease than a cancer which begins somewhere else in the body and spreads to the bone (secondary bone cancer). Primary bone cancer is rare; only about 2,500 new cases are diagnosed each year in the US. Symptoms of bone cancer include pain in the bones, fatigue, fever, weight loss, and anemia, but none of these symptoms is a definite sign of bone cancer.

Death rates from all cancers combined have been on the decline since the early 1990s. Death rates decreased for 11 of the top 15 cancers in men, and eight of the top 15 cancers in women. Lung cancer deaths rates among women leveled off for the first time between 1995 and 2001, after continuously increasing for many decades.