Antibiotic, Antiviral and Antifungal Prophylaxis for an Immune System Weakened by Cancer

Cancer itself, or more often cancer treatments, can weaken a patient's immune system; this is called cancer-related immunosuppression . The frequency and degree of cancer-related immunosuppression vary according to the drugs used and the type of cancer, but a patient with a weakened immune system develops a risk of opportunistic infection . Both bacteria and viruses and fungi can cause opportunistic infections in an immunosuppressed person, and separate preventive measures are available for each. Treatments preventing opportunistic infections are called antimicrobial prophylaxis . This prophylactic approach involves giving patients various antibiotic, antifungal or antiviral drugs before an infection develops.

Following the article by Randy A. Taplitz and colleagues in the Journal of Clinical Oncology , ASCO, one of the world's leading professional cancer societies, and the Infectious Diseases Society of America updated their antimicrobial prophylaxis guidelines for cancer-related immune suppression. In other words, new information was published on how to protect adult cancer patients against the risk of opportunistic infections arising from a weakened immune system.

The following two terms are most frequently used to describe cancer-related weakening of the immune system: leukopenia and neutropenia

The terms leukopenia and neutropenia are often used interchangeably. However, they describe somewhat different conditions. Leukopeniais an umbrella term indicating a decrease in any type of white blood cell. Neutropeniais a type of leukopenia, but specifically refers to a decrease in neutrophils, the most common type of white blood cell. A person's neutrophil count is an important indicator of infection risk. If fever accompanies a low white blood cell count, the condition is called febrile neutropenia as its name.

- Related topic: What Are Leukopenia and Neutropenia? (In Detail)

Key recommendations in the Antimicrobial Prophylaxis Guideline for Cancer-Related Immunosuppression are summarized below:

Antibacterial prophylaxis (protection against bacterial infections)

Patients at risk of febrile neutropenia should be systematically assessed, including other patient-, cancer- and treatment-related factors (in consultation with infectious disease specialists when necessary).

Acute myeloid leukemia / myelodysplastic syndrome (AML / MDS), or hematopoietic stem cell transplantation patients, for example, are at high risk of febrile neutropenia or profound, prolonged neutropenia; prophylaxis with a fluoroquinolone antibiotic (such as levofloxacin) is recommended. In patients with solid tumors, antibiotic prophylaxis isnotroutinely recommended (for example, lung and breast cancer).

Antifungal prophylaxis (protection against fungal infections)

Antifungal prophylaxis (for example, against Candida) with an oral triazole (fluconazole, itraconazole) or a parenteral (intravenous) echinocandin (Eraxis) is recommended in patients at risk of prolonged neutropenia, such as those with acute myeloid leukemia/myelodysplastic syndrome or stem cell transplantation. Antifungal prophylaxis is not routinely recommended for solid tumor patients.

Once thought to be a parasite but later recognized as a fungus, Pneumocystis jiroveciican cause pneumonia; prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) is recommended for patients receiving chemotherapy regimens with a high risk (>%5) of this pneumonia.

Antiviral prophylaxis (protection against viral infections)

Herpes simplex virus-seropositive patients undergoing allogeneic stem cell transplantation or leukemia induction therapy should receive prophylaxis with a nucleoside analog (e.g., acyclovir).

Treatment with a nucleoside reverse transcriptase inhibitor (e.g., entecavir or tenofovir) is recommended for patients at high risk of hepatitis B virus reactivation.

Annual influenza vaccination with an inactivated vaccine is recommended for all patients receiving cancer chemotherapy, all patient relatives and healthcare workers.

- Related topic: Can Cancer Patients Receive Influenza or Pneumonia Vaccines?

Additional recommended measures

All healthcare workers should follow hand hygiene and respiratory hygiene/cough practices to reduce aerosol-based and direct or indirect contact transmission of pathogenic (harmful) microorganisms in healthcare settings.

Patients who develop neutropenia due to cancer treatment should avoid prolonged exposure to environments with high concentrations of airborne fungal spores (for example, construction and demolition sites, heavy soil exposure during gardening, or home renovation).

So far, we have discussed measures taken before blood counts fall. Once neutropenia, which denotes a decrease in immune cells, has developed, afterward patients may also be prescribed antibiotics. We often adopt this approach in solid cancers where we do not expect very profound neutropenia. This aims to prevent febrile neutropenia, a serious treatment adverse effect. If febrile neutropenia has developed, the patient must be hospitalized and multiple antimicrobial treatment started.