Why Nutrition Matters in Oncology
Cancer and its treatments frequently disturb metabolism, appetite, and the ability to ingest or absorb nutrients. Malnutrition worsens fatigue, delays wound healing, increases infection risk, and may reduce tolerance to chemotherapy or radiotherapy. Early identification of patients at nutritional risk allows timely interventions that improve quality of life, treatment outcomes, and survival.
Key Risk Factors
- Advanced disease stage or rapidly progressing tumors
- Headandneck, gastrointestinal, or pancreatic cancers (direct impact on swallowing or digestion)
- Intensive treatment regimens (highdose chemotherapy, concurrent chemoradiation)
- Preexisting comorbidities such as diabetes, chronic kidney disease, or COPD
- Weight loss >5% over 1month or >10% over 6months
- Reduced oral intake (<50% of estimated needs) for more than 7 days
- Pain, nausea, vomiting, mucositis, dysphagia, or altered taste
When to Screen
Screening should be performed at the first oncology encounter, before the start of any major treatment, and repeated at regular intervals (e.g., every 24weeks) or whenever a clinical change occurs.
Validated Screening Tools
The following instruments have been widely studied in cancer populations. Choose a tool that fits the clinical setting, workflow, and expertise available.
| Tool | Primary Focus | Time Required | Cutoff for High Risk |
|---|---|---|---|
| PGSGA (PatientGenerated Subjective Global Assessment) | Weight change, dietary intake, symptoms, functional status | 510min | Score 9 |
| NRS2002 (Nutrition Risk Screening 2002) | Impaired nutrition & disease severity | 25min | Total score 3 |
| MUST (Malnutrition Universal Screening Tool) | BMI, weight loss, acute disease effect | 35min | Score 2 |
| MNASF (Mini Nutritional Assessment Short Form) | Older adults, frailty | 5min | Score 11 |
PGSGA is the most specific for oncology because it includes cancerrelated symptoms (e.g., mucositis, dysphagia). NRS2002 is quick and integrates disease severity, making it suitable for busy outpatient clinics. The remaining tools are useful when the patient population is predominantly elderly or when a universal hospital screening program is already in place.
Interpreting the Results
Once a patient scores above the defined cutoff, they are classified as high nutritional risk. Highrisk patients should be referred promptly to a dietitian or a multidisciplinary nutrition support team for a full nutrition assessment (e.g., SGA, body composition analysis, biochemical markers). Those scoring below the cutoff are not excluded from monitoring; periodic rescreening remains essential.
Nutrition Interventions After a Positive Screen
- Dietary counseling personalized advice on energydense foods, texture modifications, and symptom management.
- Oral nutritional supplements (ONS) highprotein, highcalorie formulas when oral intake is insufficient.
- Enteral nutrition tube feeding (e.g., nasogastric, PEG) for patients with severe dysphagia but a functioning gut.
- Parenteral nutrition reserved for cases where the gastrointestinal tract cannot be used or is contraindicated.
- Pharmacologic support appetite stimulants (megestrol acetate, mirtazapine) or agents that reduce catabolism.
- Exercise and physical therapy to preserve lean body mass and improve functional capacity.
Multidisciplinary Approach
Effective nutritional care requires collaboration among oncologists, surgeons, nurses, dietitians, pharmacists, and social workers. Structured pathways, such as Nutrition Care Protocols, ensure that the screen triggers defined actions and that documentation of interventions is standardized.
Case Illustration
Patient: 58yearold man with locally advanced pancreatic adenocarcinoma, scheduled for neoadjuvant chemotherapy.
Screening (Day 0): NRS2002 score=4 (weight loss=6% in 2weeks; disease severity=2). Classified as high risk.
Followup assessment: PGSGA score=12 (severe anorexia, nausea, pain). Dietitian recommends: Highcalorie ONS (2250mL daily) Small, frequent meals with added mediumchain triglycerides Antiemetic optimization and analgesia adjustment.
Outcome: After 3weeks, weight stabilised, PGSGA reduced to 8, and chemotherapy dose intensity was maintained. Continued monitoring every 2weeks throughout treatment prevented further decline.
Key Takeaways
- Malnutrition is common and detrimental in cancer; systematic screening is the first line of defense.
- Screen at baseline and repeat regularly; tools such as PGSGA or NRS2002 are validated for oncology.
- A positive screen should trigger a full nutrition assessment and timely, individualized interventions.
- Integrating nutrition into the oncology care pathway improves treatment tolerance, reduces complications, and can extend survival.
