The ABCs of blood cells and blood cancers: Lymphoma

There is a good chance that anyone who works outside of medicine is mostly unfamiliar with the different types of blood cells in our bodies. Many people learn about this topic during biology lessons in school, but then usually have little reason to think about it later in life. This all changes however should a cancer diagnosis enter the picture.  Soon there is great interest in, and new knowledge around, a person’s “blood counts.”

Blood is a specialized bodily fluid that circulates through the body via the cardiovascular system, delivering vital nutrients and helping remove waste. About 50% of blood is made up of plasma, a yellowish fluid that is mostly water. The remaining cell types are all made in bone marrow, yet each with an important job to do: 

• Red blood cells transport oxygen from the lungs through the body and carry carbon dioxide back to the lungs for exhalation. These are the most numerous blood cell type we have, usually making up about 40% of blood volume.
• Platelets promote blood clotting so that wounds can properly heal. Though small in volume compared to red blood cells, platelets are essential tools that rush to injuries to prevent blood loss.
• White blood cells defend the body against infections and illness.

Blood cells are commonly measured (or counted) using a routine blood test called a CBC (Complete Blood Count). This panel test looks at a sample of blood to measure various components. A standard result scale is used to indicate for each component, what is a normal amount versus what is low or high. Out of range results may point to a potential problem in need of further investigating or tests. For example, a low red blood cell count may suggest the presence of anemia.

Lymphoma development

There are five types of white blood cells that work together in maintaining a healthy system that can protect itself against illness:

• Neutrophils that kill bacteria
• Monocytes that clean up dead cells and pathogens
• Eosinophils that combat parasites and help with allergic responses
• Basophils that release histamine during allergic reactions
• Lymphocytes that produce antibodies and destroy malignant cells

There are three main types of lymphocytes: B cells, T cells, and Natural Keller cells. They each play a unique role in helping the body recognize and fight off infections. Should these cells become unhealthy and triggered to divide and multiply, a lymphoma (cancerous tumor) develops.

A high count of lymphocytes on a CBC is not a definitive cancer diagnosis but rather a diagnostic clue, particularly if there is a swollen lymph node or other physical sign. As abnormal lymphocytes multiply, they can accumulate in lymph nodes, bone marrow, the spleen, or other organs. When this happens, the area may become visibly swollen. As masses grow larger, it becomes difficult red blood cells to function. At the same time, diseased lymphocytes can no longer destroy infectious threats.

Non-Hodgkin Lymphoma (NHL) is a type of lymphoma that can grow from B cells, T cells, or Natural Killer cells. There are more than 60 subtypes of NHL, some of which are slow-growing, others of which are aggressive. The most common form is known as B-Cell Lymphoma. This, like many forms of NHL, is commonly treated with a combination of chemotherapy agents known as R-CHOP (Rituximab, Cyclophosphamide, Doxorubicin, and Vincristine, along with a steroid, Prednisone). A person with NHL may receive from between 3-8 cycles of this depending on tumor specifics.

During recovery from chemotherapy, patients continue to undergo bloodwork including regular CBCs to check for changes. Monitoring blood cell counts helps the care team understand the if the patient immunocompromised (and at risk for infections). This data also helps treating oncologists detect complications and/or adjust treatment plans accordingly. For example, low platelet levels can lead to bruising, bleeding gums, or even serious internal bleeding.

For a patient with lymphoma, white cell values are especially important as they can give a sense for how the body is responding to treatment -- high lymphocyte counts may suggest ongoing presence of cancerous cells while decreasing counts after treatment can indicate that the therapy is having the intended effect: shrinking or eliminating the lymphoma.