A 71-year-old man was diagnosed with prostate cancer approximately 1 year ago. At that time he weighed 182 lbs (with a height of 75 in). He has progressively lost weight since then and is now found to weigh 148 lbs. Although he reports a moderate loss of appetite, it does not correlate with his total weight loss. Which of the following mediators is most likely contributing to this patient’s decrease in weight?
(A) C-reactive protein
(B) vomplement 3a protein
© interleukin-2
(D) parathyroid hormone-related protein
(E) tumor necrosis factor
(E) Progressive weight loss, anorexia, and weakness comprise the wasting syndrome known as cachexia that is often associated with cancer. Although patients report anorexia and abnormalities in taste, the reduction in caloric intake does not sufficiently explain the often profound degree of wasting. While the mechanism is poorly understood, cancer frequently causes an increased metabolic rate that is postulated to occur as a result of cytokine production by both the tumor and the host response to the tumor. Avariety of cytokines may function synergistically to cause cachexia; however, experimental animal studies suggest that tumor necrosis factor is the major contributor. C-reactive protein and complement 3a protein (choices Aand B) both act as opsonins in acute inflammation, while interleukin-2 (choice D) is an important growth factor for the proliferation of T-lymphocytes. Parathyroid hormonerelated protein (choice E) production is responsible for causing the hypercalcemia paraneoplastic syndrome associated with certain malignancies, most notably carcinomas of the lung and kidney.