When you don’t have enough firepower to fight off infections after chemotherapy
BY Dr Azlin Ithnin & Dr Tan Toh Leong
OUR blood is composed of different types of cells, namely: red cells, white cells and platelets. And what exists among the white cells are various ‘soldiers’ assisting the immune system of the body. They are neutrophils, lymphocytes, monocytes, eosinophils and basophils.
The neutrophils normally constitute about 60-70 per cent of the total white cell count. They circulate in the blood and are found inactive in our bone marrow. The neutrophils take approximately six days to enter the blood circulation from the bone marrow, and they have a circulating life span of between eight hours to five days. Within the blood, neutrophils respond early to signals reporting injury or infection, and migrate to the affected area.
They have a role in both directly killing cells that are foreign to the body such as bacteria by phagocytosis (engulfment of cells) and chemical damage, and they can also activate other types of white cells to also take part in the immune process.
How chemotherapy can badly affect our immune system
In patients who are diagnosed with cancer, the treatment offered is usually chemotherapy with or without radiotherapy, depending on the type of cancer. The treatment is designed to kill cancer cells by damaging the DNA beyond repair.
The mechanism behind this damage differs based on the type of chemotherapy used.
The more rapidly dividing normal tissues such as hair follicles, mucosal linings and bone marrow cells can also be affected, which explains why patients can get hair loss, inflammation of the mucosal tissue and suppression of the bone marrow when receiving chemotherapy.
When the bone marrow is suppressed, it leads to low white cell counts and specifically low neutrophil counts (neutropenia), low red cell counts (anaemia) and low platelet counts (thrombocytopenia).
For the majority of chemotherapy regimens, the neutrophil count falls to its lowest level approximately five to seven days after administration of chemotherapy and can take up to two to four weeks to recover. The time may defer depending on different types chemotherapy given.
Lack of neutrophils lead to sepsis
When one is neutropenic, there are not enough neutrophils to help protect the body from invasive infection and this may cause overwhelming sepsis and death. This is specifically called neutropenic sepsis.
When this occurs, the body does not try to only attack the germs invading the system, the body’s response also injures our own tissues and organs. Deterioration can be very rapid, sometimes without an obvious focus for infection.
If left untreated, death due to neutropenic sepsis has been reported to be between two to 21 per cent. There is a tendency for neutropenic sepsis to occur more commonly in the first two cycles of treatment. Also, blood cancers are noted to be the most common type of cancer associated with neutropenic sepsis.
Not all will have it
However, not all patients undergoing chemotherapy will develop neutropenic sepsis. The risk varies greatly according to the treatment regimen and whether supportive treatment has been given together with the chemotherapy.
Other risk factors for neutropenic sepsis can include elderly patients, patients who depend on others for their basic needs, poor nutritional status, underlying blood cancers and intensity of chemotherapy.
Neutropenic sepsis is a medical emergency that requires immediate hospital investigation and further treatment.
As the mortality rate associated to neutropenic sepsis is high, any patients undergoing chemotherapy which have a neutrophil count of less than 0.5 x109/L associated with a high temperature of more than 38°C (even one reading) will be immediately treated with antibiotics.
Hence it is important for the patient and family members to be aware when the patient is feeling unwell and have a spike of fever to bring the patient immediately to the hospital without waiting for other symptoms to appear. — The Health
Dr Azlin Ithnin is the Vice President of Malaysian Sepsis Alliance and a Senior Lecturer and Chemical Pathologist Consultant, UKM Medical Center, Universiti Kebangsaan Malaysia
Assoc Prof Dr Tan Toh Leong is thePresident and Founder of Malaysian Sepsis Alliance and a Senior Lecturer and Emergency Medical Consultant, UKM Medical Center, Universiti Kebangsaan Malaysia