As indicated at the beginning of this chapter, the syndrome of cancer cachexia resembles several nutritional syndromes such as starvation or protein-calorie malnutrition. It is clear, however, that this aspect of the host-tumor relationship is extremely complex, involving not only nutritional factors but also a wide variety of humoral and hormonal components, many of which are known and a number of which are undoubtedly unknown. The idea that humoral factors or hormones may be critical in the causation of cachexia was actually first suggested more than four decades ago by Nakahara and Fukuoka (1958), who proposed that a hormone-like substance that they termed toxohormone was responsible for significant changes in the tumor-bearing host, particu- larly a depression of the level of the enzyme catalase in the liver. Although the concept of toxo- hormone is generally not considered as significant in the cachectic syndrome today, this original work pointed the way to the present-day understanding that numerous hormones and humoral factors are involved in the cancer cachexia syndrome.
Cancer cachexia is among the most devastating syndromes associated with advanced can- cer and may account directly for between 10% and 22% of all cancer deaths (cf. Tisdale, 1997). The ideal therapy of cancer cachexia is obviously complete removal of the offending neoplasm. Since this is usually not possible because of metastatic spread, various modes of therapy have been employed to relieve symptomatology when treatment of the neoplasm has been relatively unsuccessful. These include the use of several different steroid hormones, both natural and syn- thetic, and more recently eicosapentaenoic acid which may be able to prevent the muscle wasting (Beck et al., 1991). The use of anabolic steroids as well as corticosteroids may produce transient effects on appetite but have not been generally successful. As with many other aspects of the cancer problem, it is apparent that only when a complete understanding of the variety of factors contributing to the syndrome of cancer cachexia is achieved will it be possible to develop effective treatment modalities for this complex interaction between the neoplasm and the host.