A common cold is typically a minor inconvenience for most healthy people, but for cancer patients, particularly those undergoing active treatment, any infection requires immediate attention. The standard immune response that clears a virus in a healthy person is often significantly hampered in a patient with cancer. This compromised state means that a mild upper respiratory infection can quickly progress to a more severe or life-threatening condition, such as pneumonia or sepsis. Therefore, monitoring symptoms closely and acting swiftly is a necessary part of cancer care.
How Cancer Treatment Compromises Immune Function
Many cancer treatments are designed to target and destroy rapidly dividing cells, the defining characteristic of cancer. This action also affects healthy cells that divide quickly, such as those in the bone marrow where blood cells are produced. As a result, treatments like chemotherapy and, to a lesser extent, radiation therapy, can suppress the bone marrow’s ability to generate sufficient white blood cells.
This reduction in infection-fighting cells leads to neutropenia, characterized by an abnormally low count of neutrophils. Neutrophils are the immune system’s first line of defense, acting as rapid responders that engulf and destroy bacteria, viruses, and other pathogens. When neutrophil counts drop, the body is left without its primary defense mechanism, making it highly susceptible to infections that would otherwise be easily controlled.
The period of lowest white blood cell count, known as the nadir, typically occurs seven to twelve days after chemotherapy and is the time of greatest risk. Different cancer treatments affect the immune system in varied ways; for example, some immunotherapies can cause an inflammatory response that mimics flu-like symptoms. Chemotherapy-induced neutropenia is the most common reason a cancer patient cannot effectively fight off a virus like the common cold, raising the risk of complications.
Warning Signs: When a Cold Becomes a Concern
While standard cold symptoms like a runny nose, sneezing, and a mild sore throat are often the first signs of illness, the most concerning symptom for an immunocompromised patient is a fever. A fever is often the only initial sign of a serious infection in someone with a low white blood cell count. The threshold for an emergency is a single temperature reading of 100.4°F (38°C) or higher, or a sustained temperature of 100.0°F (37.8°C) or higher for one hour.
This elevation in temperature, especially when accompanied by neutropenia, is termed febrile neutropenia, which is treated as a life-threatening emergency requiring immediate attention. Beyond fever, other warning signs that a cold is progressing include shaking chills, which signal the body is trying to fight a pathogen. Respiratory symptoms indicating a deeper problem include shortness of breath, a new or worsening cough, or chest pain.
Other serious signs of infection can include diarrhea, vomiting, pain with urination, new abdominal pain, or redness, swelling, or tenderness around a catheter site. Changes in mental status, such as confusion or sudden forgetfulness, are also red flags requiring immediate medical evaluation. These symptoms suggest the infection is spreading and must be addressed urgently to prevent complications like sepsis.
Immediate Steps When Symptoms Appear
The most important step upon noticing any cold symptoms, particularly a fever, is to contact the oncology care team immediately. Patients should not wait for regular office hours or attempt to manage symptoms at home. The oncology clinic’s after-hours or emergency contact number should be readily available.
When reporting symptoms, be specific about the highest temperature reading, the time it was taken, and any accompanying symptoms like chills, cough, or pain. Patients should not take over-the-counter fever-reducing medications like acetaminophen or ibuprofen before speaking with the care team. These medications can mask the fever and delay necessary treatment, making it more difficult for professionals to assess the severity of the underlying infection.
The likely protocol after reporting a fever involves being directed to the nearest emergency department or cancer center for immediate evaluation. Once there, the patient can expect blood tests, including a complete blood count to check the neutrophil level, and blood cultures to identify the source of a bacterial infection. Due to the high risk, broad-spectrum intravenous antibiotics are typically started immediately before culture results are available.
Strategies for Minimizing Infection Risk
Proactive measures are necessary for cancer patients to reduce the risk of contracting respiratory illnesses during treatment. Consistent and thorough hand hygiene is fundamental, requiring washing hands with soap and water for at least twenty seconds, especially before eating and after being in public. Patients should avoid close contact with anyone who shows signs of illness and limit time spent in crowded indoor spaces.
Wearing a face mask in public settings can help reduce the inhalation of airborne pathogens, especially during peak cold and flu seasons. Discussing appropriate vaccinations with the oncology team is a preventative measure, as shots for influenza, COVID-19, and pneumonia may be recommended. Maintaining a balanced diet and adequate hydration also supports the immune system’s function.