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Cancer
What Is Cancer?
Cancer is an abnormal growth of cells. Cancer cells rapidly reproduce despite restriction of space, nutrients shared by other cells, or signals sent from the body to stop reproduction. Cancer cells are often shaped differently from healthy cells, they do not function properly, and they can spread to many areas of the body. Tumors, abnormal growth of tissue, are clusters of cells that are capable of growing and dividing uncontrollably; their growth is not regulated.
Oncology is the study of cancer and tumors. The term "cancer" is used when a tumor is malignant, which is to say it has the potential to cause harm, including death.
Stanford Cancer Center: Innovations In Cancer Care
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.
INTERESTED IN AN ONLINE SECOND OPINION?
The Stanford Medicine Online Second Opinion program offers you easy access to our world-class doctors. It’s all done remotely and you don’t have to visit our hospital or one of our clinics for this service. You don’t even need to leave home!
Visit our online second opinion page to learn more.
Condition Spotlight
Clinical Trials for Cancer
Clinical trials are research studies that evaluate a new medical approach, device, drug, or other treatment. As a Stanford Health Care patient, you may have access to the latest, advanced clinical trials.
Open trials refer to studies currently accepting participants. Closed trials are not currently enrolling, but may open in the future.
Cancer
What is cancer? Cancer is overly prolific, abnormal cell growth. Learn about benign, malignant, locally invasive, metastatic, primary and secondary cancers.
cancer cancers abnormal cell growth benign cancer malignant cancer primary tumor secondary tumor metastatic cancer