The cancer critical care paradox

SummaryA normal inflammatory response is a necessary reaction to injury or infection. It has proinflammatory components, intended to promote healing and repair, and anti-inflammatory components, to terminate and limit the response. The response is complex with significant inter-individual variability. It may be modulated by multiple factors including cancer and its treatment. Cancer causes considerable immune dysfunction through a number of mechanisms. Cancer therapies, including surgery, chemotherapy, radiotherapy and transplantation, also have profoundly detrimental immunomodulatory effects. The resultant abnormal inflammatory response may cause excessive activation of proinflammatory or anti-inflammatory components, with consequent progression to critical illness. A deranged inflammatory response may also affect carcinogenesis by proinflammatory promotion of cancer growth and spread or anti-inflammatory suppression of anti-tumour immunity. In addition, techniques and medications used to provide organ support during cancer-related critical illness may unwittingly further disorder inflammatory responses and have negative effects on the underlying cancer.This review article explores this complex relationship between inflammation, critical illness and cancer and introduces the concept that critical illness and its management may influence cancer growth and spread.