Cancer is something that we all know but one that few of us can define. While we might be fully aware that it's a "bad thing," understanding the very nature of the beast — how it starts, why it happens — is another matter altogether. Cancer, also called malignancy, is an abnormal growth of cells. There are more than 100 types of cancer, including breast cancer, skin cancer, lung cancer, colon cancer, prostate cancer, and lymphoma. Symptoms vary depending on the type. Cancer treatment may include chemotherapy, radiation, and/or surgery. Cancer is the second-leading cause of death in the United States. But survival rates are improving for many types of cancer, thanks to improvements in cancer screening and cancer treatment. Symptoms Signs and symptoms caused by cancer will vary depending on what part of the body is affected. Some general signs and symptoms associated with, but not specific to, cancer, include: Fatigue Lump or area of thickening that...