Viral and Bacterial Pneumonia in HNSCC

Risks of viral and bacterial pneumonia are increased among HNSCC patients receiving chemotherapy and/or radiotherapy given the presence of unique risk factors (e.g. depressed immune function, older age, malnutrition, smoking and alcohol abuse, tumor location, and comorbidities).8,26,54-56 Pulmonary viral infections frequently occur in patients with impaired cellular immunity, with cytomegalovirus and herpes group viruses being common sources.11 Influenza, parainfluenza, respiratory syncytial virus, rhinovirus, and adenovirus, are also recognized as frequent pulmonary pathogens, particularly among immunocompromised cancer patients with respiratory illness.10,12,57,58
Bacterial co-infection and secondary insults in HNSCC patients can lead to severe respiratory complications. Influenza-bacterial and rhinovirus-pneumococcal pneumonia have been associated with increased mortality.59 Streptococcus pneumoniae andStaphylococcus aureus are also commonly observed, accounting for as many as 35% and 28% of co-infections, respectively.60 The type of bacterial pneumonia in cancer patients depends on multiple factors including mechanism and duration of the underlying immunologic defect and whether the infection is community acquired or nosocomial.
In a review of healthcare-associated infections in HNSCC patients treated with chemotherapy and/or RT, respiratory tract infections were most common.55 Pseudomonas aeruginosarepresented the majority of gram-negative organisms (49%) compared to gram-positive pathogens (35%), where Staphylococcus aureuspredominated. Smoking, malnutrition, and presence of a tracheostomy tube are significant risk factors for nosocomial infections in this population.55,61 A prospective analysis by Panghal et al. revealed that HNC patients treated with chemoradiation (CRT) are prone to oral cavity bacterial infections, especially withStaphylococcus aureus .62 Common oral flora, including anaerobes, are commonly responsible for lower respiratory infections, particularly in patients with dysphagia and aspiration.63,64