100+ Free CSO Practice Questions

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A patient with newly diagnosed colorectal cancer is overweight (BMI 31). According to AICR/WCRF survivor recommendations, the BEST nutrition focus is:

Aggressive weight loss of 10 lbs/month during chemotherapy

Resume previous diet without changes

Maintain weight or modest, intentional weight loss after treatment if appropriate; emphasize plant-forward, fiber-rich, lean-protein pattern

Strict ketogenic diet during treatment

to track

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2026 Statistics

Key Facts: CSO Exam

150

Total Items

125 scored + 25 pretest

3 hrs

Time Limit

CDR

34%

Largest Domain Weight

Nutrition Assessment

2,000 hrs

Required Experience

Oncology nutrition within 5 years

$350

US Exam Fee

$475 international

5 years

Certification Validity

CDR

The CSO (Board Certified Specialist in Oncology Nutrition) exam is administered by CDR. The exam consists of 150 multiple-choice items (125 scored + 25 pretest) over 3 hours. The fee is $350 US / $475 international. Eligibility requires an active RD/RDN credential plus 2,000 hours of oncology practice within the past 5 years. Nutrition Assessment is the largest domain at 34%. Mastery of PG-SGA, GLIM, Fearon cachexia, ESPEN cancer guidelines, and disease-site-specific MNT is essential. Year-round PSI testing.

Sample CSO Practice Questions

Try these sample questions to test your CSO exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which of the following BEST describes the Warburg effect in cancer cells?

A.Increased fatty acid oxidation for ATP production

B.Preferential use of aerobic glycolysis even in the presence of oxygen

C.Enhanced ketone body utilization by tumor cells

D.Decreased glucose uptake by malignant tissue

Explanation: The Warburg effect describes the tendency of cancer cells to preferentially metabolize glucose through aerobic glycolysis (producing lactate) even when oxygen is plentiful. This metabolic reprogramming supports rapid biosynthesis of nucleotides, lipids, and amino acids needed for tumor proliferation. It is a hallmark of cancer metabolism.

2A 62-year-old patient with metastatic pancreatic adenocarcinoma has lost 8% of body weight in 4 months and reports loss of appetite and muscle wasting. Per the Fearon 2011 international consensus, this patient meets criteria for:

A.Pre-cachexia

B.Cancer cachexia

C.Refractory cachexia

D.Sarcopenic obesity

Explanation: Per Fearon et al. (2011), cancer cachexia is defined by weight loss greater than 5% over 6 months in absence of simple starvation, OR BMI <20 with any weight loss >2%, OR sarcopenia with weight loss >2%. This patient's 8% loss in 4 months meets the primary criterion. Cachexia is also characterized by anorexia and systemic inflammation.

3Per ESPEN cancer guidelines, the recommended protein intake for an oncology patient with cachexia and adequate renal function is:

A.0.8 g/kg/day

B.1.0 g/kg/day

C.1.2 to 1.5 g/kg/day, up to 2 g/kg/day

D.Greater than 3 g/kg/day

Explanation: ESPEN guidelines recommend protein intake of at least 1.0 g/kg/day, with target of 1.2 to 1.5 g/kg/day for cancer patients, and up to 2 g/kg/day in those with cachexia or systemic inflammation, provided renal function is adequate. Higher protein supports lean body mass preservation in the setting of anabolic resistance.

4A patient receiving radiation therapy to the head and neck reports painful oral ulcers, difficulty swallowing, and decreased intake. Which dietary modification is MOST appropriate for this acute mucositis?

A.Spicy foods to stimulate appetite

B.Soft, moist, bland foods at cool or room temperature

C.Hot, acidic broths to soothe the throat

D.Coarse, high-fiber foods to maintain bowel function

Explanation: For mucositis, soft, moist, bland foods served cool or at room temperature minimize mucosal irritation and pain. Cold or cool textures provide a numbing effect. Avoiding extremes of temperature, acid, spice, and rough textures reduces discomfort and helps maintain intake during treatment.

5Which laboratory finding is MOST suggestive of tumor lysis syndrome (TLS)?

A.Hyponatremia, hypokalemia, hypocalcemia

B.Hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia

C.Hypernatremia, hypercalcemia, hypophosphatemia

D.Hypoglycemia, hypomagnesemia, alkalosis

Explanation: Tumor lysis syndrome occurs when rapid tumor cell breakdown releases intracellular contents into the bloodstream. The classic tetrad is hyperkalemia, hyperphosphatemia, hyperuricemia, and secondary hypocalcemia (calcium binds the released phosphate). TLS is most common in hematologic malignancies (Burkitt lymphoma, ALL) at treatment initiation.

6On the PG-SGA, a patient scores 12 and is categorized as Stage B. The MOST appropriate interpretation is:

A.Well nourished, no nutrition intervention required

B.Moderately malnourished or suspected malnutrition; intervention indicated

C.Severely malnourished; aggressive intervention warranted

D.Score is invalid; reassess in 2 weeks

Explanation: On the Patient-Generated Subjective Global Assessment (PG-SGA), Stage B indicates moderately malnourished or suspected malnutrition. A numerical score of 9 or greater triggers the need for critical symptom management and nutrition intervention by the dietitian along with patient/family education.

7A patient with pancreatic cancer reports steatorrhea, weight loss, and bloating after meals. The MOST appropriate intervention is:

A.Initiate a low-fat diet (less than 20 g/day)

B.Begin pancreatic enzyme replacement therapy (PERT) with meals and snacks

C.Recommend a high-fiber diet

D.Initiate parenteral nutrition immediately

Explanation: Pancreatic enzyme replacement therapy (PERT) is the standard of care for pancreatic exocrine insufficiency, which causes maldigestion, steatorrhea, and weight loss. Typical dosing starts at 25,000 to 50,000 units of lipase per meal and 10,000 to 25,000 units per snack, taken with the first bite of food.

8Which statement BEST reflects current evidence on the neutropenic diet for adult oncology patients?

A.Strict neutropenic diet significantly reduces infection rates

B.Current evidence does not support strict neutropenic diet; safe food handling practices are recommended

C.All raw fruits and vegetables must be avoided indefinitely after chemotherapy

D.The neutropenic diet should continue for one year after treatment completion

Explanation: Multiple randomized trials and systematic reviews have shown that strict neutropenic diets do not reduce infection rates compared with safe food handling practices. Current ASPEN, AND, and most cancer center guidelines emphasize FDA food safety practices over food restriction in neutropenic patients.

9A patient with head and neck cancer is scheduled for definitive concurrent chemoradiation. Which intervention is associated with the BEST nutritional outcomes?

A.Wait for greater than 10% weight loss before considering enteral access

B.Proactive placement of a prophylactic gastrostomy (G-tube) prior to treatment in high-risk patients

C.Use only oral nutrition supplements regardless of intake

D.Initiate TPN at the start of radiation

Explanation: Prophylactic gastrostomy placement in high-risk head and neck cancer patients (e.g., advanced stage, planned chemoradiation, baseline dysphagia or weight loss) is associated with reduced weight loss, fewer hospitalizations, and improved completion of treatment. Decisions should be individualized but proactive enteral access is preferred for high-risk groups.

10A patient receiving capecitabine should be counseled to avoid which food or supplement due to a clinically significant interaction?

A.Grapefruit and grapefruit juice

B.Cruciferous vegetables

C.Calcium-fortified foods

D.Whole grain breads

Explanation: Capecitabine, like many fluoropyrimidines and chemotherapeutic agents metabolized via CYP3A4, can have altered metabolism with grapefruit, which inhibits CYP3A4. This may increase drug exposure and toxicity. Patients are typically counseled to avoid grapefruit and grapefruit juice.

About the CSO Exam

Specialty certification for Registered Dietitians providing nutrition care to oncology patients across the cancer care continuum. The CSO validates expertise in cancer biology and treatment modalities, validated cancer nutrition assessment (PG-SGA, GLIM, Fearon cachexia), MNT for treatment-related side effects (mucositis, dysgeusia, nausea, diarrhea, GVHD), disease-site-specific protocols (head/neck, pancreatic, gastric, HSCT/BMT, brain), oncologic emergencies, drug-nutrient interactions, supplement and herbal cautions during therapy, and survivorship plus palliative/EOL nutrition.

Questions

150 scored questions

Time Limit

3 hours

Passing Score

Scaled

Exam Fee

$350 US / $475 international (CDR)

CSO Exam Content Outline

20%

Cancer and Cancer Treatment

Cancer biology, treatment modalities, side-effect profiles

34%

Nutrition Assessment

PG-SGA, GLIM, Fearon cachexia, ESPEN energy/protein

27%

Nutrition Interventions

MNT for side effects, disease-site protocols, EN/PN, oncologic emergencies

19%

Education and Counseling

Motivational interviewing, supplement cautions, survivorship, palliative/EOL

How to Pass the CSO Exam

What You Need to Know

Passing score: Scaled
Exam length: 150 questions
Time limit: 3 hours
Exam fee: $350 US / $475 international

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CSO Study Tips from Top Performers

1Master PG-SGA: 4 patient-completed boxes (weight history, food intake, symptoms, function) + clinician sections; numeric score determines intervention; triage A (0-1, no intervention) vs B (2-8, education + assess) vs C (≥9, urgent intervention)

2Memorize Fearon 2011 cachexia: weight loss >5% in 6 mo OR BMI <20+wt loss >2% OR sarcopenia + wt loss >2%. Stages: pre-cachexia → cachexia → refractory

3Know ESPEN cancer nutrition: 25-30 kcal/kg, protein 1.2-1.5 g/kg (up to 2.0 in cachexia), no benefit from antioxidant supplementation during chemo/RT (may interfere)

4Master disease-site MNT: head/neck (prophylactic G-tube discussion before RT), pancreatic (PERT 25,000-50,000 U lipase per meal), post-gastrectomy (small frequent, separate liquids/solids, low simple sugars for dumping), HSCT/BMT (acute GI GVHD diet phases I-V)

5Know herbal cautions: St. John's wort = CYP3A4 inducer (reduces cyclophosphamide, irinotecan, imatinib, tamoxifen); green tea EGCG may inhibit bortezomib; high-dose antioxidants may interfere with chemo/RT efficacy

Frequently Asked Questions

Who is eligible for the CSO exam?

You need an active CDR Registered Dietitian (RD or RDN) credential held for at least 2 years plus a minimum of 2,000 hours of documented oncology nutrition practice within the past 5 years. The exam is offered year-round through PSI test centers.

What is PG-SGA and why does it matter?

The Patient-Generated Subjective Global Assessment (PG-SGA) is the validated cancer-specific nutrition screening and assessment tool. It generates a numeric score plus a triage category: A (well nourished), B (moderately or suspected malnourished), C (severely malnourished). Higher scores indicate greater intervention need. PG-SGA is the gold-standard cancer nutrition assessment and is heavily tested on the CSO exam.

How is cancer cachexia diagnosed?

Per Fearon 2011 international consensus, cancer cachexia requires ANY of: (1) weight loss >5% in 6 months, OR (2) BMI <20 + weight loss >2%, OR (3) sarcopenia + weight loss >2%. Three stages: pre-cachexia → cachexia → refractory cachexia (advanced cancer, low performance status, life expectancy <3 months). Energy/protein needs increase: 25-30 kcal/kg + 1.2-1.5 g/kg protein (up to 2.0 in cachexia per ESPEN).

Should oncology patients follow a neutropenic diet?

Current evidence does NOT support a strict neutropenic diet for cancer patients with neutropenia. Multiple RCTs and systematic reviews show no reduction in infections compared to standard food-safety practices. Recommend safe food handling per FDA Food Safety Guidelines instead — proper temperature control, hand hygiene, washing produce, avoiding high-risk foods (raw oysters, unpasteurized dairy, deli meats not reheated). HSCT/BMT centers may have specific protocols.

How should I study for the CSO exam?

Plan 60-100 hours over 8-12 weeks. Focus heaviest on Nutrition Assessment (34%) and Nutrition Interventions (27%) — together over 60% of exam. Master PG-SGA, GLIM, Fearon cachexia staging, ESPEN cancer nutrition guidelines, treatment-side-effect management (mucositis, dysgeusia, anorexia agents like olanzapine and mirtazapine), disease-site protocols (head/neck, pancreatic with PERT, post-gastrectomy, HSCT/BMT GVHD), and supplement cautions during active therapy.