Different types of cancer can behave very differently. For example, lung cancer and breast
cancer are very different diseases. They grow at different rates and respond to different
treatments. This is why people with cancer need treatment that is aimed at their particular
kind of cancer.
Not all tumors are cancerous. Tumors that aren't cancer are called benign. Benign tumors can
cause problems – they can grow very large and press on healthy organs and tissues. But they
cannot grow into (invade) other tissues. Because they can’t invade, they also can't spread to
other parts of the body (metastasize). These tumors are rarely life threatening.