The clinical outcome for 1362 patients with active cancer managed on home parenteral nutrition (HPN) is compared with that of 122 patients with radiation enteritis ("cured" cancer) and 416 patients with Crohn's disease. This longitudinal clinical information was reported to the North American Home Parenteral and Enteral Nutrition Registry (Oley Foundation/A.S.P.E.N. joint project) between 1985 and 1989. The data shows that the number of active cancer patients on this therapy is increasing 13% per year. The annual survival rate is 25% for patients with active cancer, as compared with 88% for patients with radiation enteritis and 95% for patients with Crohn's disease. Although 50% of all active cancer patients starting HPN are dead within 6 to 9 months, the prognosis is somewhat better in children, and 20% of these active cancer patients appear to do well, returning to full oral nutrition and experiencing complete rehabilitation. These are presumed to be patients with a potentially curable cancer requiring super-aggressive treatment, which causes temporary severe gastrointestinal dysfunction. Adult active cancer patients have the same rehospitalization rate for HPN complications (once per year) as radiation enteritis and Crohn's disease patients. However, their rehospitalization rate for non-HPN complications is four times higher. This article reviews the factors that may explain the growth of HPN in active cancer patients and discusses some of the unanswered clinical questions that urgently need to be addressed to more effectively determine the appropriateness or inappropriateness of HPN management in the active cancer setting.