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