Cancer is the growth of abnormal cells that can invade tissues and spread to other parts of the body. There are over 100 types of cancer that are diagnosed through biopsies and have varying treatments depending on the type and stage. A cancer diagnosis causes anxiety for patients and loved ones. While some causes are unknown, risk factors include smoking, obesity, lack of exercise, poor diet, alcohol consumption and sun exposure. Treatments include chemotherapy, radiation, surgery, immunotherapy and bone marrow transplants. Side effects of cancer and its treatment include anemia, fatigue, hair loss, constipation, lymphedema and chemotherapy-induced diarrhea.