Cancer is a disease in which some cells of the body grow uncontrollably and spread to other parts of the body.
Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and multiply (through a process called cell division) to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.
Sometimes this orderly process breaks down, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumors, which are lumps of tissue. Tumors can be cancerous or not cancerous (benign).
Cancerous tumors spread into, or invade nearby tissues and can travel to distant places in the body through lymphatic system or cirlulatory system and form new tumors in other organs. Spread of cancer is called metastases.
In breast, tumor can be spread to lymph nodes near breast. Tumor can also be spread to other organs through circulatory system. Metastatic cancer has the same name and the same type of cancer cells as the original, or primary cancer. For example, breast cancer that forms a metastatic tumor in the bone is “metastatic” breast cancer, not bone cancer, and behaves similar to breast cancer. Doctors call the new tumor “distant” or “metastatic disease.”