Issue link: https://www.massageandbodyworkdigital.com/i/82405
pathology perspectives BY RUTH WERNER BLOOD CANCERS When Helpful Turns Harmful When we think of cancer, most of the time we think of piles of mutated cells accumulating into tumors that crowd out healthy tissue cells, get first dibs on our nutrients to grow even bigger, and threaten to use our lymphatic system to travel to other places, wreaking havoc as they go. The structures most often associated with this activity are epithelial cells: they are designed to replicate quickly, so they are vulnerable to subtle mutations that change their characteristics from friendly to unfriendly. This description is relatively accurate for some epithelial cancers, including colorectal, for example. But among the most common cancers in our country, and definitely the most common cancers in children, we see an entirely different type of tissue involved and an entirely different growth pattern. These cancers do not affect the epithelial cells of the lungs, colon, breast ducts, or prostate gland. These cancers affect our bodies' other fast-growing cells: the blood cells that are manufactured in bone marrow. Here we will take a short look at each of the three most common hematological cancers: leukemia, lymphoma, and myeloma. First, let's do a quick review of white blood cells and their functions. • Myeloid cells—Myeloid cells, also called granulocytes, are manufactured in bone marrow. They can be delineated into neutrophils, basophils, and eosinophils and monocytes. Each of these has a role to play in nonspecific immune defense. The life span of a myeloid cell varies from a few hours to many days or weeks, depending on circumstances. • Lymphocytes—These white blood cells may be manufactured either in bone marrow or in lymphoid tissue (including lymph nodes, the spleen, and other locations). They include T cells, which direct specific immune responses against identified invaders, and B cells, which manufacture antibodies to disable identified invaders. Natural killer cells are also lymphocytes; they are associated with the ability to identify and attack cancer cells. Hematologic cancers involve the production of white blood cells— either in bone marrow or in lymph tissue—that have changed their properties from helpful to harmful. How each disease affects function depends on the growth pattern of the particular cancer involved. LEUKEMIA Leukemia, or "white blood," is a group of cancers that affect several types of white blood cells. It used to be thought that leukemia was completely distinct from lymphoma, but research methods that allow scientists to track cell lineage more precisely have revealed that some types of leukemia affect the same cells as some types of lymphoma, so the delineation between these diseases is now largely tied to location: leukemia begins in bone marrow and releases mutated cells into the bloodstream, while lymphoma begins in lymph tissue and cells usually accumulate rather than travel. Boost your practice with ABMP's Website Builder—free for members on ABMP.com 101