Most blood cancers start in the bone marrow, a spongy and soft material that forms the center of the bone. These make stem cells, which mature over time to become platelets, white blood cells, and red blood cells. Blood cancer starts in the bone marrow, affecting the blood cells’ production and impairing their function. As a result, several symptoms start to develop. So, here are some common warning signs of different types. Leukemia Leukemia is a type of cancer that originates in the bone marrow. It causes an abnormal increase in white blood cells, which live longer than they should. However, these excess cells do not function properly to fight off infections, leading to a weakened immune system and feelings of illness. The severity of symptoms depends on the rate at which the disease progresses. Sometimes, leukemia progresses quite quickly. In such cases, the first warning signs often include a sudden feeling of sickness, similar to coming down with the flu. Other times, leukemia may take years to cause any symptoms to occur. In either case, the first signs of the cancer are often apparent when a routine blood test shows abnormal results. Over time, the cancerous cells start to disrupt the growth and functioning of the healthy blood cells.