What type of cancer begins in blood-forming tissues and results in abnormal blood cells?

Leukemia is the type of cancer that starts in blood-forming tissues, primarily the bone marrow, leading to the production of abnormal white blood cells. These abnormal cells can interfere with the body's ability to fight infections and can crowd out healthy blood cells, disrupting normal blood functions. It is characterized by an overproduction of these atypical cells, which can accumulate in the blood and bone marrow, affecting overall health.

Myeloma, on the other hand, specifically involves the plasma cells in the bone marrow and does not primarily result in the same type of abnormal blood cells found in leukemia. Sarcomas originate in connective tissues such as muscles, bones, and cartilage, rather than blood-forming tissues. Carcinomas are cancers that develop in epithelial tissue and are not associated with blood cell formation either. Thus, leukemia is uniquely defined by its origin in blood-forming tissues and its results in the proliferation of dysfunctional blood cells.