Inside a Tumor: What Is Cancer? Video Series
![](/sites/g/files/xnrzdm211/files/oembed_thumbnails/GBYR3db8RFOc2NFjQnzuoDzPTjDoq3JDLVHzwXVoYMI.jpg)
Inside a Tumor: What Is Cancer? Video Series
A cancerous tumor is an abnormal mass of tissue that forms when cells grow and divide uncontrollably and spread into the surrounding area. Learn about other cells found within a tumor and some of their effects.