Most patients with cancer will have frequent bloodwork done to monitor their general health and check for potential side effects of treatment. People commonly have quick access to their blood test results, either in print form from their oncology team, or through an electronic medical record. These reports are filled with lists of important numbers but don’t frequently come with complete explanations of the results. This series will provide you with a guide to understanding what your team is looking for when they review your blood test results.   

CBC - Complete Blood Count.  

One of the most common blood tests performed is the Complete Blood Count (CBC). This test measures the number and proportion of a few types of cells in the blood. All the values in a CBC have a normal range. Knowing the number of these cell types, and if they are within normal ranges, gives your team important information about your cancer, how your body is tolerating treatment, and other medical problems or complications (such as infections or bleeding disorders). Cancer treatments, including chemotherapy, targeted therapy, hormone therapy, and radiation, as well as the cancer itself, can all cause lower than normal values. These treatments can destroy the cells or make it difficult for the bone marrow that makes these cells at a normal rate.  

A note on Neutrophils:  

Neutrophils are a specific type of white blood cell that are closely monitored due to the potential for some cancer treatments to cause neutropenia, or a low number of neutrophils. These cells are measured with an extra test that can be ordered with a CBC called a Differential. The Differential provides the specific number of specific types of cells, neutrophils being one; the Absolute Neutrophil Count (ANC) is the number that your oncology team will be monitoring. Neutrophils are particularly important in fighting infections caused by bacteria. When you are neutropenic, or with a low number of neutrophils, the body is more susceptible to bacterial infections and normal signs of infection may be delayed or not present at all. In these cases, fever is often the only sign of infection, and is a medical emergency because infections can become severe very quickly.  

If you experience a fever of 100.4 or higher, or any other sign of infection listed above during treatment, you should notify your oncology team immediately.  

Fluctuations 

Note: It is normal for these values to change slightly with each test. Many factors can cause blood levels to be slightly out of normal range, which by itself may not be concerning. It is important to discuss any questions that you have regarding bloodwork results with your oncologist.   

When to Contact Your Doctor, Health Care Provider, or Iris Oncology Nurse: 

• You are experiencing fever  

• You have unusual bleeding, bruising, or red spots under your skin 

• You are experiencing dizziness or shortness of breath 

• You have concerns about any symptoms that you are experiencing 

Questions to ask your doctor: 

• What signs or symptoms of low blood counts should I be looking for during treatment?  

• Are there certain days or periods during treatment that my blood levels may be lower than normal?  

• Are there any precautions I should take? 

• Which new symptoms should I report to you?  

• How do I contact my doctor or nurse if I have a concern?