Management of Chemotherapy Side Effects

General Principles & CINV Intro - Chemo's Cruel Kickbacks

• Chemotherapy targets rapidly dividing cells: impacts cancer & normal tissues (bone marrow, GIT, hair follicles).
• Management Pillars:
  • Prophylaxis: Anticipate & prevent predictable toxicities.
  • Dose Modification: Adjust or delay based on severity of side effects.
  • Supportive Care: Hydration, nutrition, growth factors (e.g., G-CSF for neutropenia, EPO for anemia).
  • Symptom Management: Tailored to specific adverse events.
• CINV (Chemotherapy-Induced Nausea & Vomiting):
  • Common, distressing; significantly impacts patient's quality of life.
  • Key Pathways: Central (chemoreceptor trigger zone - CTZ) & peripheral (gut vagal afferents).
  • Neurotransmitters: Serotonin (5-HT₃), Substance P (NK₁).
  • Types: Acute (<24h), Delayed (>24h), Anticipatory, Breakthrough, Refractory.

⭐ CTCAE (Common Terminology Criteria for Adverse Events) is widely used for grading toxicity and guiding management decisions across clinical trials and practice.

CINV Management - Vomit Veto

• Goal: Prevent CINV by targeting key neurotransmitters (Serotonin, Substance P, Dopamine).
• Risk Assessment: Crucial for regimen selection (High, Moderate, Low, Minimal emetogenic risk).
• CINV Phases:
  • Acute: <24 hrs post-chemo.
  • Delayed: >24 hrs post-chemo, up to 5 days.
  • Anticipatory: Before chemo, conditioned response.
• Core Drug Classes:
  • 5-HT3 Antagonists: (Ondansetron, Granisetron). Palonosetron (long-acting, good for delayed).
  • NK1 Receptor Antagonists: (Aprepitant, Fosaprepitant). Key for HEC; target Substance P.
  • Corticosteroids: (Dexamethasone). Synergistic, broad antiemetic.
  • Olanzapine: Atypical antipsychotic; multi-receptor antagonist for breakthrough/refractory.
  • Benzodiazepines: (Lorazepam). For anticipatory CINV.

⭐ NK1 receptor antagonists (e.g., aprepitant) are crucial for preventing delayed CINV with highly emetogenic chemotherapy.

Myelosuppression Mayhem - Blood Cell Blues

Bone marrow suppression by chemo → pancytopenia. Nadir: 7-14 days post-chemo.

• Neutropenia (↓ Neutrophils): ANC < 1500/mm³ (Severe < 500/mm³).

  • Manage: G-CSF (Filgrastim, Pegfilgrastim). 📌 Mnemonic: "Grandma Fil Needs Pegs for her Low Neutrophils."
  • Prophylaxis: G-CSF if Febrile Neutropenia (FN) risk > 20%.

  ⭐ Febrile neutropenia (ANC < 500/mm³ + fever) is a medical emergency requiring prompt broad-spectrum antibiotics.

• Anemia (↓ RBCs): Fatigue, pallor.

  • Manage: ESAs (Epoetin, Darbepoetin; Target Hb 10-12 g/dL). Transfusion if Hb < 7-8 g/dL / symptomatic.

• Thrombocytopenia (↓ Platelets): Platelets < 150,000/mm³ (Severe < 50,000/mm³).

  • Spontaneous bleed risk < 10,000-20,000/mm³.
  • Manage: Platelet transfusions. Oprelvekin (IL-11) - limited use.

Other Common Toxicities - Systemic Sucker Punches

• Cardiotoxicity:
  • Anthracyclines (Doxorubicin): Cumulative; LVEF monitoring. Prevent: Dexrazoxane.
  • Trastuzumab: Reversible LVEF dysfunction.
• Pulmonary Toxicity:
  • Bleomycin: Pneumonitis/fibrosis (max 400 units).
  • Busulfan: "Busulfan lung".
  • Methotrexate: Acute pneumonitis.
• Nephrotoxicity:
  • Cisplatin: ATN. Hydration, Amifostine. Monitor GFR.
  • Methotrexate (high dose): Crystalluria. Alkalinize urine, Leucovorin, hydration.
• Neurotoxicity:
  • Vincristine: Peripheral neuropathy (sensory, motor, autonomic).
  • Cisplatin: Peripheral neuropathy, ototoxicity.
  • Ifosfamide: Encephalopathy. Antidote: Methylene blue.
  • Cytarabine (high dose): Cerebellar toxicity.
• Hemorrhagic Cystitis: (Cyclophosphamide, Ifosfamide - Acrolein)
  • Prevention: Hydration, MESNA.

⭐ MESNA (Sodium 2-mercaptoethane sulfonate) is crucial for preventing hemorrhagic cystitis with cyclophosphamide/ifosfamide by neutralizing acrolein.

• Mucositis/Stomatitis: (5-FU, MTX, Doxorubicin)
  • Management: Oral hygiene, cryotherapy, Palifermin.
• Hand-Foot Syndrome: (Capecitabine, 5-FU, Liposomal Doxorubicin)
  • Management: Dose modification, cooling, emollients, Pyridoxine. oka

High‑Yield Points - ⚡ Biggest Takeaways

• Nausea/Vomiting: Key drugs: 5-HT3 antagonists (ondansetron), NK1 antagonists (aprepitant).
• Myelosuppression: Use G-CSF (neutropenia), EPO (anemia), Oprelvekin (thrombocytopenia).
• Hemorrhagic Cystitis (cyclophosphamide/ifosfamide): Prevent with Mesna and good hydration.
• Cardiotoxicity (doxorubicin): Dexrazoxane offers protection; monitor LVEF.
• Mucositis: Palifermin (KGF) promotes healing; good oral hygiene essential.
• Tumor Lysis Syndrome: Manage with hydration, allopurinol, or rasburicase.
• Diarrhea (irinotecan, 5-FU): Treat with loperamide; octreotide for severe cases.