Respiratory infections and cancer

Respiratory infection may be associated with the risk of the development of malignancy. There are well-established associations between bacterial and viral pathogens and cancer development in other organs, but fewer data are available for the risk of lung cancer in relation to respiratory pathogens. Chronic lung inflammation is associated with increased risk of cancer development and disruption of the resident lung microbiome is increasingly recognised as a risk factor for cancer development and progression. This is particularly relevant in diseases such as COPD where patients are at increased risk of lung cancer. Patients with cancer are at markedly increased risk of infection, with pneumonia accounting for more than 50% of cases of septic shock in this population. Pneumonia in patients with cancer carries a poor prognosis and may be associated with “typical” bacterial pathogens such as Streptococcus pneumoniae or opportunistic pathogens particularly in patients receiving chemotherapeutic agents. This chapter reviews the interaction between respiratory infection and cancer.