About Cancer

Cancer is not a single disease – it is a large, complex family of disease that can affect virtually every part of the body. Physicians diagnose more than 1.3 million cases of cancer every year – with half of those cases occurring in the lung, prostate, breast, colon and rectum. Cancer is second only to heart disease as the leading cause of death in the U.S. and, although it can strike at any age, cancer is more common in people 50 or older.

Cancer begins in the body's cells, which constantly divide and multiply to replace old, damaged cells. Sometimes, cells begin to divide unnecessarily, forming excess tissue known as a tumor. In many cases, these tumors are not cancerous – they are benign. While benign tumors may cause health problems depending on their size and location, they are generally not life-threatening. If, however, abnormal cells begin to divide, they may form a malignant, or cancerous, tumor.

Most malignant tumors grow rapidly, invading nearby organs and tissues -- a process referred to as metastasis. Cancerous cells can also travel through the bloodstream to other regions of the body.