Immune System Compromise
Cancer and its treatments weaken the body’s natural defenses, increasing vulnerability to fungal infections. Immune system suppression, a common consequence of the disease and its therapies, allows opportunistic fungi to thrive.
Neutropenia, a reduced number of neutrophils (white blood cells fighting infections), is a key factor. Chemotherapy and radiation therapy target rapidly dividing cells, including bone marrow cells that produce protective immune cells. When neutrophil counts drop, the body loses a primary defense against fungal pathogens.
Other cancer treatments impair immune function. Corticosteroids, administered for inflammation or chemotherapy side effects, can suppress macrophages. Stem cell transplants involve intensive chemotherapy and radiation that temporarily decimate the patient’s immune system before new cells engraft.
Physical barriers can also be compromised. Chemotherapy can cause mucositis (inflammation and damage to mucous membranes), creating open sores for fungal entry. Central venous catheters, essential for administering medications, can serve as direct pathways for fungi into the bloodstream, leading to serious systemic infections.
Certain cancers, particularly hematological malignancies like leukemia and lymphoma, directly affect bone marrow and blood cells, compromising immune function even before treatment. These patients often experience prolonged immune suppression, increasing risk.
Common Fungal Infections
Several fungal pathogens commonly affect cancer patients. Candida species are frequent culprits, causing candidiasis. These yeasts are naturally found on skin and in the gastrointestinal tract, but become problematic with immune suppression. Infections can manifest as oral thrush (white patches in mouth and throat) or esophageal candidiasis (pain and difficulty swallowing).
Beyond localized infections, Candida can enter the bloodstream, leading to candidemia or invasive candidiasis, which spreads to various organs. While Candida albicans was historically most common, other non-albicans Candida species like C. glabrata and C. tropicalis have become increasingly prevalent, some exhibiting antifungal resistance.
Aspergillus species cause aspergillosis. These molds are common in the environment (soil, decaying vegetation, dust). In immunocompromised individuals, inhaling Aspergillus spores can lead to lung infections, ranging from localized to invasive aspergillosis, where the fungus invades lung tissue and spreads.
Pneumocystis jirovecii is a fungus responsible for Pneumocystis pneumonia (PCP), a serious lung infection primarily seen in individuals with severely weakened immune systems. PCP can cause significant respiratory distress, requiring prompt diagnosis and treatment. The risk of PCP is elevated in patients undergoing certain chemotherapy or high doses of corticosteroids.
Other notable fungal infections include Cryptococcus neoformans (cryptococcosis, often affecting the central nervous system) and molds like Fusarium and Mucorales (aggressive, difficult-to-treat infections). The specific type of fungal infection often depends on the degree of immune suppression and environmental exposures.
Identification and Treatment
Prompt identification and treatment of fungal infections in cancer patients are vital due to their compromised immune status and rapid progression. Diagnosis often involves a combination of methods: blood tests for fungal markers or DNA, and cultures to identify fungal species.
Imaging scans (CT scans or X-rays) visualize fungal infections in organs like the lungs or sinuses. A biopsy (small tissue sample) may confirm diagnosis and identify the pathogen. The choice of diagnostic test depends on the suspected site and type of infection.
Treatment typically involves antifungal medications, administered orally or intravenously, depending on infection severity and type. Common antifungal drug classes include azoles (e.g., fluconazole, voriconazole), echinocandins (e.g., caspofungin, micafungin), and polyenes (e.g., amphotericin B). Echinocandins are often preferred for initial treatment of severe Candida infections.
Antifungal agent selection is individualized, considering the fungal species, drug susceptibility, patient health, and potential drug interactions with cancer treatments. Some Candida species may be azole-resistant, necessitating alternatives. Prompt intervention is crucial, as delayed treatment can lead to widespread infection and poorer outcomes.
Managing underlying factors contributing to infection is also important. This may involve removing central venous catheters if suspected sources, or adjusting immunosuppressive medications. Antifungal drugs can have side effects and interact with chemotherapy drugs, requiring careful monitoring.
Proactive Measures
Proactive steps can reduce fungal infection risk in cancer patients. Maintaining personal hygiene is important, including frequent handwashing (especially before eating and after using the restroom) and regular bathing with mild soap to reduce skin fungal load.
Environmental awareness aids prevention. Patients should avoid areas with high mold concentrations (construction sites, dusty environments, stagnant water). Avoid gardening or digging in soil without proper protective gear (gloves and masks), as soil harbors fungal spores. Avoiding direct contact with bird droppings or animal waste minimizes exposure.
Proper food handling and preparation are important. Patients should avoid raw or undercooked meats, unwashed fruits and vegetables, and unpasteurized dairy products, which can carry fungi. Cooked foods should be stored properly and consumed within a safe timeframe. Filtering tap water in high-risk situations may be considered based on medical advice.
Patients and caregivers should be alert for any signs of infection and report them immediately to their healthcare team. Symptoms such as fever, chills, new rashes, oral sores, cough, or difficulty breathing require prompt medical attention. Early reporting allows for timely diagnosis and intervention, preventing infections from becoming more severe.
In some high-risk situations, healthcare providers may prescribe prophylactic antifungal medications to prevent infections. These preventive drugs are typically used for patients undergoing intensive chemotherapy or stem cell transplantation, where fungal infection risk is particularly high. This strategy is determined by the medical team based on individual patient risk factors.