10.3.1 Classification and pathophysiology of the anorexia–cachexia syndrome
Most of the patients with advancing, incurable illness experience an involuntary loss of body weight and of most often appetite, accompanied by fatigue and muscle weakness and psychological distress, involving also their loved ones. This clinical condition can be summarized as cachexia syndrome (CS) or wasting disease. It is a very frequent, but poorly recognized clinical problem( 1 , 2 ). In cancer, prospective epidemiology data suggest that many patients suffering from cachexia are not recognized( 3 ). In contrast to this neglect, another clinical problem is the overtreatment of cachexia by artificial nutrition (lacking in advanced cancer illness often achievable meaningful treatment goals)( 4 ) and probably also by pharmacological anti-cachexia interventions (narrow and short effect of progestins and corticosteroids)( 5 ).
The strong meaning of eating (e.g. eating = life, expressing love by eating, my daily bread give me today)( 6 ), at least in patients with certain cultures and religious backgrounds( 7 ), may contribute to pressure of patients and families to preserve the normal and associated eating-related distress( 8 ). It remains challenging not only for patients, but also professionals, to understand ‘what is happening with me’, given the complex pathogenesis of cachexia. Also it’s a hard piece of work and maturation to achieve a new meaning and hope with less physical function and food( 9 ).
In order to improve the treatment of the cachexia, development of a consensus on how to define and perform staging of cachexia seems appropriate. The ‘old’ classification of anorexia–cachexia syndrome, applying only weight loss and loss of appetite is recognized as not sufficient to guide clinical practice and trials. New insight into the complexity of cachexia calls for more complex interventions.
This chapter will provide an update on the evolving understanding of anorexia–cachexia, with a focus on patients with advanced cancer. It reviews the current definition, diagnosis, and classification, the mechanism involved in primary cachexia, the causes of secondary/starvational anorexia and cachexia, implications on clinical decision-making, and finally provides an outlook to future therapeutic strategies and clinical trial design.
