NSCLC and FDG PET-CT Scan

Case Summary: Yosef Fernandez

• Yosef Fernandez, a 62-year-old male, is undergoing chemotherapy for non-small cell lung cancer (NSCLC).
• He has a history of type 2 diabetes for six years and hypertension for ten years.
• Also suffering from increasing fatigue, breathing difficulties, a chronic cough, right-sided chest pain, and unexplained weight loss.
• Stopped smoking after diabetes diagnosis but still consumes three cigarettes a day.
• His mother had breast cancer, and his father had hypertension.
• A lesion in his right lung was discovered seven months ago via CT scan.
• Vital signs were steady, but he appears fatigued.
• A Positron Emission Tomography - Computed Tomography (PET-CT) scan using Fluorodeoxyglucose (FDG) is suggested to analyze the tumor's metabolic activity, identify the cancer's stage, and determine the effectiveness of treatment.
• FDG's pharmacokinetics, patient preparation and safety considerations need to be explained.
• Complains of fatigue and trouble breathing.
• Weight loss of 9 pounds over the past months.
• No known allergies.
• Appears alert, awake, cooperative but fatigued.
• BP: 128/82 mmHg, HR: 88 bpm, RR: 13/min, Temp: 98.6°F or 37.0°C, SpO2: 94% on room air
• Experiences fatigue, persistent cough, sudden weight loss, trouble breathing, and swallowing.

Medications

• Metformin 500 mg for type 2 diabetes mellitus
• Lisinopril 10 mg for hypertension
• Carboplatin 250-500 ml
• Pemetrexed 100 ml
• Pembrolizumab 100 ml

Prescription Writing

• 18-Fluorodeoxyglucose: 5-10 mCi IV for PET-CT imaging of the tumor.
  • NPO for 4-6 hours before the scan.
  • Rescan if BG >200 mg/dL
  • Increase water intake after administration to facilitate clearance.
• Metformin (Glipizide): 2.5 mg, take one tablet once a day with food.
• Vitamin B12 (Hydroxocobalamin): 1 mg IM prior to the first cycle of Pemetrexed, then every 9 weeks.
• Folic Acid: 400 mcg tablet, one tablet once a day
  • Start one week before the first cycle and continue until 3 weeks after the last cycle.
• Dexamethasone: 4 mg tablet
  • One tablet two times a day for 3 days, starting 24 hours before chemotherapy.
• Pembrolizumab: 50 mg IV administer in 100 ml sodium chloride 0.9% over 30 minutes.
• Pemetrexed: 500 mg IV administer in 100 ml sodium chloride 0.9% over 10 minutes.
• Sodium Chloride: 0.9%, 100 ml/bottle, 2 bottles.
• Carboplatin: 150 mg IV administer in 250-500 ml Glucose over 30-60 minutes.
• Glucose: 5%, 500 ml bottle.

Pharmacokinetics of FDG

• Absorption: Administered intravenously to bypass gastrointestinal absorption.
• Distribution: Behaves like glucose, transported by GLUTs, accumulates in high-glucose-demand organs (brain, heart, cancer cells).
• Metabolism: Lacks a hydroxyl group (replaced by 18-fluorine), which is essential for glucose metabolism.
• Hexokinase phosphorylates FDG to FDG-6-phosphate, which cannot be further metabolized.
• Excretion: Unmetabolized FDG is excreted via urine within 24 hours.

Pharmacodynamics of FDG

• Mechanism of Action: FDG is a glucose analog and radioactive tracer.
• It's transported into cells with high glycolysis rates but cannot be further metabolized, leading to accumulation and radioactive decay.
• Result = images for diagnosing malignancies and abnormal metabolic rates.
• Receptors: Unlike traditional receptors, FDG uses GLUTs for cellular entry.
• Hexokinase phosphorylates cells, forming FDG-6-phosphate that gets trapped.
• Effect: FDG has no biological or therapeutic effect but helps identify diseases through diagnostic imaging in PET scans.
• It can detect accumulated FDG and evaluate lung tumor activity and overall patient well-being.

Pharmacological Management

• Aimed at managing Type 2 Diabetes Mellitus and NSCLC.
• For Type 2 Diabetes Mellitus: Glipizide/Metformin to decrease plasma glucose levels and restore energy production.
• NSCLC: Carboplatin (Immunotherapy), Pemetrexed (Immunotherapy), and Pembrolizumab (Chemotherapy).
  • These damage the DNA of cancer cells to prevent cell division and cause cell death.
  • Cancer cells block T-cell activity, preventing immune recognition.
  • Pembrolizumab blocks PD-1, allowing T-cells to recognize and attack cancer cells.
• Cycle Frequency: 21 days
• Pre-Medication: Vitamin B12 (hydroxocobalamin): 1mg given the week before the first cycle, then every 9 weeks until pemetrexed treatment is completed.
  • Pemetrexed should be administered at least 48 hours after vitamin B12.
  • Subsequent vitamin B12 injections may be administered on the same day as pemetrexed.
• Folic acid: 400 microgram dose should be started at least 1 week before the first cycle and continue until 3 weeks after the last cycle.
• Dexamethasone: 4mg, 3 days before treatment
• Pembrolizumab: Administer 100mL of sodium chloride
• Pemetrexed: Administer 100mL of sodium chloride over 10 minutes.
• Carboplatin: Administer in 250-500mL of glucose over 30-60 minutes.
• Patient needs to be monitored for reactions
• May increase your chance of bleeding or interact with your cancer treatment
• Withhold Glipizide/Metformin 48 hours before taking it again.
• Reduce the side effects of Pemetrexed with Folic Acid Tablets to counter chemotherapy toxicity without impacting its therapeutic effect.
• Reduce Vitamin B12 injections to mitigate its hematologic toxicity
• Provide Corticosteroids (Dexamethasone) to help lower the chance of getting any skin problems.
• Hypersensitivity
• Severe myelosuppression, renal impairment, hearing impairment
• Pregnancy (lactation)
• History of severe hypersensitivity reaction to pemetrexed

Non-Pharmacological Management

• Pre-treatment:
  • Overall assessment of Mr. Fernandez's current lifestyle, medical issues and medical history
• Patient Education:
  • Provide information about NSCLC and potential side effects.
  • Offer education on diabetes management.
  • Discuss the importance of follow-up appointments and treatment plans.
• Mitigate Diabetes Mellitus:
  • Monitor blood sugar levels to maintain recommended levels.
  • Encourage monitoring food intake.
• Nutrition and Hydration:
  • refer to a dietitian for personalized dietary plan.
  • Promote hydration.
• Discuss interventions for symptom relief:
  • Breathing exercises and techniques for managing shortness of breath.
  • Light exercises to avoid muscle tension.
  • Mindfulness or meditation.
• Post Treatment:
  • Encourage hydration.
  • Schedule a regular follow-up plan.

Critical Thinking Question

• How would the body respond to FDG administration if the patient's blood sugar level was unregulated before the procedure?