Weight loss and nutritional deterioration are associated with adverse outcomes in terms of cancer prognosis (response rate and survival) as well as increased complications, prolonged hospitalizations, increased risk of unplanned hospitalization, increased disability, and increased overall cost of care. The nutritional oncology service at Fox Chase Cancer Center defined a proactive, standardized assessment and interventional approach from 1987-1994. In 186 consecutive patients referred to the nutrition clinic and managed solely by oral intervention and aggressive symptom management, the team demonstrated a 50%-80% success rate in getting patients to maintain or gain weight during therapy, with a similar success in maintaining or improving visceral protein status as determined by serum transferrin and/or albumin. Evaluation of the home parenteral nutrition program (n = 65, from 1987-1993) demonstrated similar success when appropriate triaging was carried out, with 58% of patients able to be tapered off parenteral nutrition (PN) entirely or with transition to enteral tube feeding. The assessment of success for a nutritional intervention (e.g., a disease-specific nutritional supplement) requires the standardization of definitions, assessment tools, criteria for nutritional intervention, and appropriate end points for the assessment of outcomes. The Patient-Generated Subjective Global Assessment of nutritional status is used in conjunction with the nutritional risk of planned cancer therapy to define a standardized interventional approach in oncology patients, which can be used in clinical practice, cooperative oncology group protocols, and clinical trials of nutritional intervention regimens.