What is Chemoradiation?

Chemoradiation (CRT) refers to the concurrent use of chemotherapy and radiation therapy to treat cancer.

Mechanism

  • Chemotherapy can increase tumor cell sensitivity to radiation by:
    • Inhibiting DNA repair after radiation-induced damage
    • Synchronizing tumor cells in radiosensitive phases of the cell cycle
    • Reducing hypoxic tumor regions
  • Radiation directly damages DNA → double-strand breaks → apoptosis

Common Chemoradiation Regimens by Cancer Type

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Cancer Type Chemotherapy Used Radiation Details Notes / Pearls
Rectal cancer 5-FU (continuous infusion) or Capecitabine (oral) 45–50.4 Gy in 25–28 fractions Neoadjuvant CRT standard for locally advanced rectal cancer; reduces local recurrence
Anal cancer 5-FU + Mitomycin C 45–59 Gy Standard definitive CRT (Nigro protocol); avoids surgery
Head & Neck (HNSCC) Cisplatin IV (high-dose q3w or weekly low-dose) 66–70 Gy Organ preservation (larynx, oropharynx); concurrent therapy improves OS
Esophageal cancer Carboplatin + Paclitaxel 41.4–50.4 Gy CROSS trial standard; neoadjuvant therapy before surgery
Cervical cancer Cisplatin weekly 45–50 Gy + brachytherapy boost Definitive CRT for locally advanced disease
NSCLC (Stage III) Cisplatin + Etoposide or Carboplatin + Paclitaxel 60–66 Gy Definitive CRT; concurrent preferred over sequential for survival
 
Key Pharmacist Considerations
  1. Drug selection:
  2. Toxicity management:
  3. Scheduling:
    • Concurrent administration increases efficacy but also toxicity compared to sequential chemo + radiation.
  4. Monitoring:
    • CBC, renal/hepatic function, hydration status, electrolyte balance
    • Assess skin, mucosa, GI for radiation–chemo overlap toxicity
  5. Patient counseling:
    • Fatigue, skin care, oral care, diarrhea management
    • Importance of adherence, especially with oral radiosensitizers like capecitabine

Summary:

Chemoradiation = concurrent chemotherapy + radiation to enhance tumor control.

  • Common in rectal, anal, head & neck, cervical, esophageal cancers.
  • Choice of chemo depends on tumor type and radiosensitizing effect.
  • Requires careful toxicity monitoring and supportive care.