By Andrew Ellsworth, MD
Like a car racing along the interstate, exiting onto a highway, and finally reaching the family farm along a dusty gravel road, our blood circulates inside our bodies. There are the major blood vessels, such as the aorta running out of the heart, and there are the tiny capillaries allowing blood cells one at a time to carry oxygen and nutrients to all the cells in our bodies. The network of capillaries is so complex it is estimated there are over 40 billion in one person, and if stretched out in a single line they would cover over 100,000 miles.
Our blood is made up of a mix of liquids and solids. The liquid, plasma, is composed of water, salts, and proteins. The solids include red blood cells, white blood cells, and platelets. In general, the red blood cells deliver oxygen and carry away carbon dioxide, the white blood cells help fight infections, and the platelets help form clots if you get a cut.
Bone marrow is the spongy material inside our bones that helps make new blood cells, which only last so long. Red blood cells last about 120 days, platelets last 6 days, and white blood cells may last less than a day or much longer.
As with any stretch of road, accidents happen. The blood cells can become clogged, causing a stroke in the brain or a heart attack in the heart. Sometimes what goes wrong is a problem of overproduction causing a cancer of the blood. Leukemia is a cancer of the white blood cells, lymphoma is a cancer of the tissues that produce and carry white blood cells, and multiple myeloma is a cancer of plasma proteins. A cancer of too many red blood cells is called polycythemia vera.
While some cancers often cause the growth of a solid tumor, the overproduction of blood cells may be harder to detect. Symptoms are often vague, including fatigue, weakness, night sweats, bone pain, weight loss, frequent infections, enlarged lymph nodes, and other nonspecific symptoms.
Advancements in cancer therapies have made large strides in the treatment of blood cancers. Besides chemotherapy and radiation therapies, treatments can include stem cell transplants, immunotherapies, and targeted therapies which are more specific on the molecular level to what is being overproduced. Immunotherapies include modifying T cells to recognize and attack cancer cells.
The complexities of the human body are endless and amazing. Part of the wonder is how the cells in our bodies are constantly growing and being replaced. Just like our highway system, there is always construction.