Background Cancer cachexia (CC) is a multifactorial syndrome characterised by ongoing skeletal muscle loss that leads to progressive functional impairment driven by reduced food intake and abnormal metabolism. Despite the traditional use of non-volitional weight loss as the primary marker of CC, there is no consensus on how to diagnose and manage CC.

Methods The aim of this narrative review was to describe and discuss diagnostic criteria and therapeutic approaches for the accredited practicing dietitian with respect to identifying and managing CC.

Results Available diagnostic criteria for cachexia include the cancer-specific (Fearon and Cachexia Score) and general criteria (Evans and Global Leadership Initiative on Malnutrition). These include phenotypic criteria [weight loss, body mass index, (objective) muscle mass assessments, quality of life] and aetiological criteria (disease burden, inflammation, energy expenditure, anorexia and inadequate food intake) and can be incorporated into the nutrition care process (NCP). This informs the nutrition diagnosis of ‘chronic disease- or condition-related malnutrition (undernutrition) as related to increased nutrient needs, anorexia or diminished intake due to CC’. Optimal nutrition care and management of CC is multidisciplinary, corrects for increased energy expenditure (via immunonutrition/eicosapentaenoic acid), suboptimal protein/energy intake and poor nutrition quality of life, and includes a physical exercise intervention. Monitoring of intervention efficacy should focus on maintaining or slowing the loss of muscle mass, with weight change as an alternative gross indicator.

Conclusions Dietitians and the NCP can play an essential role with respect to identifying and managing CC, focusing on aspects of nutrition screening, assessment and intervention.