Does chemotherapy always cause a decrease in white blood cells?

White blood cells are our body’s “warriors” against infection, and a decrease in their number can lead to a variety of infections and, in severe cases, death.

Does chemotherapy always cause a decrease in white blood cells? What are the other signs of chemotherapy-induced myelosuppression? How can the first signs be detected early? Let’s talk about it.

Does chemotherapy always affect white blood cells?

In fact, different chemotherapy drugs have different effects on various components of the hematopoietic system, related to the specific mechanism of action of each drug. Usually, the degree of leukocyte decline is related to the variety and dose of chemotherapy drugs. Cyclophosphamide, cisplatin, and fluorouracil cause a mild-moderate decrease in leukocytes; while anthracyclines, paclitaxel, docetaxel, and carboplatin cause a moderate-to-severe decrease. For example, docetaxel has a greater effect on white blood cells. One study showed that about 27% or more of lung cancer patients using this drug experienced severe decreases in leukocytes and neutrophils (a component of white blood cells). In addition, the effect of chemotherapy dose on leukocytes is dose-dependent, with the higher the dose of chemotherapy drug used per square meter of body surface area, the more pronounced the decline in leukocytes.

Of course, different people have different levels of tolerance to the side effects of the drug. In general, patients in good physical condition and on initial treatment tend to have better bone marrow function and less impact from drug side effects. In contrast, patients with repeated chemotherapy tend to have poorer bone marrow function and greater drug effects.

According to the World Health Organization’s Acute and Subacute Toxic Reaction Criteria for Anticancer Drugs, we usually classify the degree of myelosuppression as 0 to IV. 0 is no myelosuppression, I to II is mild, and III to IV is severe. See Table 1 for details:

Table 1 Fractionation of myelosuppression after chemotherapy
	0 degrees	1 degree	2 degrees	3 degrees	4 degrees
Hemoglobin (g/L)	Not less than 110	109~95	94~80	79~65	Less than 65
White blood cells (×10/L)	Not less than 4.0	3.9~3.0	2.9~2.0	1.9~1.0	Less than 1.0
granulocytes (×10/L)	Not less than 2.0	1.9~1.5	1.4~1.0	0.9~0.5	Less than 0.5
platelets (×10/L)	Not less than 100	99~75	74~50	49~25	Less than 25

The clinical presentation of myelosuppression varies with the degree of myelosuppression. Below we describe what symptoms may be present with myelosuppression.

What are the “telltale signs” of bone marrow suppression?

What are the “signs” of myelosuppression?

The sequence of myelosuppression and reduction in peripheral blood cell components after chemotherapy is related to the life cycle of the cells. Neutrophils are short-lived, so their reduction occurs first; thrombocytopenia is a little later; and red blood cells are longer-lived and their reduction occurs later, most often in the context of long-term chemotherapy.

Neutrophils are an important component of leukocytes, and their reduction is of greater clinical importance than leukopenia. The decrease in granulocytes usually begins 1 week after chemotherapy discontinuation and reaches a nadir by 10-14 days after discontinuation. In general, mild leukopenia tends to be asymptomatic, and to a certain extent, patients may feel weak and dizzy. In severe cases (usually degree III-IV), immune deficiency, fever, and infection occur.

Another common “sign” of bone marrow suppression is a decrease in platelet count. In general, thrombocytopenia occurs slightly later than neutropenia and is often minimized about 2 weeks after chemotherapy. It is also closely associated with certain chemotherapy regimens, such as gemcitabine in combination with carboplatin, which is associated with moderate to severe thrombocytopenia in about 50% of lung cancer patients. Platelets are our body’s “outpost” for stopping bleeding, and insufficient platelets can lead to bleeding, which can manifest as bleeding spots or bleeding patches on the skin, or in severe cases, even vomiting blood or blood in the stool (dark, tar-like stools).

In addition to white blood cells and platelets, there is another “mainstay” of the blood, red blood cells, whose numbers are reduced when the bone marrow is suppressed, which is often referred to as “anemia. “According to the 2012 China Tumor-Related Anemia Survey, more than 60% of tumor patients have anemia, which is closely related to the patient’s nutrition, physical fitness, and radiotherapy received. In general, patients with poor nutritional status and repeated chemotherapy are more likely to develop anemia, which clinically manifests itself mainly as pallor, fatigue, which cannot be relieved even after rest, and in severe cases, they may suffer from panic, dyspnea, and fainting.

Can myelosuppression due to chemotherapy be avoided and remedied?

Before chemotherapy begins and throughout the course of chemotherapy, the doctor will monitor the patient’s blood work closely, which means that blood is drawn regularly to see if the levels of various blood components are normal. If there are “signs” of bone marrow suppression, on the one hand, if the level of a blood component is too low, it will be considered a “supplemental” transfusion of blood components (platelets, red blood cells, etc.), but also in combination with certain “stimulating factors” to stimulate the bone marrow. “On the other hand, the severity of myelosuppression may determine whether the chemotherapy regimen needs to be adjusted to avoid the continued use of highly myelosuppressive chemotherapeutic agents;

In conclusion, myelosuppression due to chemotherapy is not uncommon, and in severe cases it can lead to complications such as lethal infections and bleeding, limiting the course of chemotherapy and directly affecting patient outcomes. Therefore, we need to identify and treat these patients early and try to turn them around.

Extended reading

Chemotherapy and myelosuppression

At present, most of the chemotherapy drugs used in the clinic are “cytotoxic drugs”, which have the disadvantage that they do not distinguish between normal cells and tumor cells, and once they enter the body, they “kill” all cells. The most likely to be “affected” is our body’s hematopoietic system, which leads to what doctors often call “bone marrow suppression”. When “myelosuppression” occurs, several major cells in the blood – white blood cells, red blood cells, platelets, etc. – may be reduced to varying degrees. Sometimes there is a decrease in one type of cell, sometimes in all of them (what doctors often call “trilineage reduction”).