The best evidence that the cancer cachexia syndrome is induced by humoral factor(s) produced by cancer cells is obtained by analyses of human tumour xenografts in mice, which develop severe cachexia; tumour resection in these mice brings about rapid regain of the lost weight.
The hypothetical factor responsible for this syndrome, originally referred to as ΓÇÿtoxohormoneΓÇÖ, has long been sought. Recent experimental studies demonstrate that two cytokines, leukaemia and IL-6 inhibitory factor, are the most likely candidates for this syndrome. Since the mechanisms responsible for cachexia in cancer patients are multifactorial, evaluation of the role of these cytokines in the development of the syndrome is difficult.
