Is cancer always bad? can my cancer get cancer? and if so would it kill my cancer or just give me extra cancer?

Cancer : Cancer is simply described as the harmful and uncontrolled growth of abnormal cells. These cells grow and divide and form malignant tumors that can invade healthy tissue and organs, as well as other parts of the body (metastasis). Within the same tumor, it is possible for sub-populations of other kinds of cancer cells to be present in a tumor that are competing for the same resources. If you are asking if a tumor can grow upon another tumor, then technically, the answer is yes. However, this would be an extension of the existing tumor since several types of mutated cells can exist within one tumor. While one sub-population of cells can out grow the other, these cells would not necessarily 'kill off'the cancer. The tumor would most likely continue to grow and spread.

Not always: Dr. Rutledge expertly answered your last 2 questions so I'll tackle the first. Cancer (just like any other disease) is never "good" in the sense that I would not want to get it. That said, many cancers are very curable in early stage and some others are curable even if advanced. In a way, some cancers could be considered less "bad" than uncontrolled diabetes, COPD, or heart failure.