What is the difference between benign and malignant cancer?
Tumors can be benign (noncancerous) or malignant (cancerous). Benign tumors tend to grow slowly and do not spread. Malignant tumors can grow rapidly, invade and destroy nearby normal tissues, and spread throughout the body.
What are "locally invasive cancer" and "metastatic cancer"?
Cancer is malignant because it can be "locally invasive" and "metastatic":
- Locally invasive cancer—The tumor can invade the tissues surrounding it by sending out "fingers" of cancerous cells into the normal tissue.
- Metastatic cancer—The tumor can send cells into other tissues in the body, which may be distant from the original tumor.
What are primary tumors?
The original tumor is called the "primary tumor." Its cells, which travel through the body, can begin the formation of new tumors in other organs. These new tumors are referred to as "secondary tumors."
The cancerous cells travel through the blood (circulatory system) or lymphatic system to form secondary tumors. The lymphatic system is a series of small vessels that collect waste from cells, carrying it into larger vessels, and finally into lymph nodes. Lymph fluid eventually drains into the bloodstream.