The proteolysis-inducing factor: In search of its clinical relevance in patients with metastatic gastric/esophageal cancer

The proteolysis-inducing factor is a putative mediator of cancer-associated weight loss. The goal of this study was to examine for the first time: (i) its prevalence in patients with metastatic gastric/ esophageal cancer; and (ii) whether it possibly correlated with weight loss and anorexia and whether it predicted tumor response and patient survival. This study recruited 41 patients as part of a phase II therapeutic, chemotherapy protocol for patients with metastatic gastric/ esophageal cancer. Patient eligibility criteria were designed to select a group of patients who would tolerate treatment with the drugs capecitabine and oxaliplatin. Urine for assaying the proteolysis-inducing factor was obtained at registration and then 6 weeks later. Patients completed the FACT-E questionnaire every 6 weeks and had their weights checked at the same interval. Patients were followed prospectively for tumor response and patient survival. Twenty-three (56%) patients had the proteolysis-inducing factor in their urine at registration, and 18 (64%) had it at 6 weeks. There was no statistically significant correlation between the presence of the proteolysis-inducing factor and weight loss or between its presence and anorexia. Moreover, there was no evidence that the presence of the proteolysis-inducing factor in urine was able to predict tumor response or patient survival. The proteolysis-inducing factor in urine does not appear to be tied to weight loss, anorexia, tumor response, or patient survival in the clinical setting of metastatic gastric/esophageal cancer.