Diagnostic criteria for cancer cachexia: data versus dogma

Cachexia limits cancer therapy, quality of life, and survival of patients with cancer. Challenges identifying and diagnosing cachexia are due to disparities in diagnostic criteria. A framework for classification of cancer cachexia was recently defined by international consensus. This review describes recent efforts to use this framework to develop definitive diagnostic criteria for cancer cachexia.

The principle proposed in the cancer cachexia framework for development of diagnostic criteria is that 'definitive cutoffs for variables could be determined from large contemporary datasets by determining the values that relate optimally to meaningful patient-centered outcomes.' Clearly defined statistical methods to examine distributions of diagnostic criteria in relation to an outcome are used to achieve this task. As a first step, a dataset of more than 11 000 cancer patients from Europe and Canada was compiled, and used to develop and validate a new grading system for cancer-associated weight loss, based on a risk stratification with survival as the outcome. The next refinements for diagnostic criteria will be enabled by the emergence of rich datasets including key variables further specifying the nature of cachexia such as skeletal muscle depletion, reduced food intake, and inflammation.

Development of diagnostic criteria for cancer cachexia is based on a solid conceptual foundation and is moving toward defining the type of assessments, optimal values, and combinations of criteria that best define cachexia. Large contemporary datasets representing different cancer populations, candidate cachexia diagnostic criteria, and clinical outcomes will further ensure developmental and validation efforts.