Targets in clinical oncology: the metabolic environment of the patient.

Cancer cachexia is a syndrome characterized by a marked weight loss, anorexia, asthenia and anemia. The degree of cachexia is inversely correlated with the survival time of the patient and it always implies a poor prognosis. Lean body mass depletion is one of the main features of cachexia and it involves not only skeletal muscle but also affects cardiac protein. The cachectic state is invariably associated with the presence and growth of the tumour and leads to a malnutrition status due to the induction of anorexia or decreased food intake. In addition, the competition for nutrients between the tumour and the host leads to an accelerated starvation state which promotes severe metabolic disturbances in the host, including hypermetabolism which leads to an increased energetic inefficiency. Unfortunately, at the clinical level, cachexia is not treated until the patient suffers from a considerable weight loss and wasting. Therefore, it is of great interest to analyze possible early markers of the syndrome. In the present review both metabolic and hormonal markers are described. Although the search for the cachectic factor(s) started a long time ago, and although many scientific and economic efforts have been devoted to its discovery, we are still a long way from fully understanding the underlying basis for this syndrome. The suggested mediators (associated with both depletion of fat stores and muscular tissue) can be divided into two categories: of tumour origin (produced and released by the neoplasm) and humoural factors (mainly cytokines). One of the aims of the present review is to summarize and evaluate the different catabolic mediators (both humoural and tumoural) involved in cancer cachexia, since they may represent targets for clinical investigations. Additionally, an overview of the main therapeutic approaches for the treatment of the cachectic syndrome is presented.