Brachytherapy

Definition

Brachytherapy is a form of internal radiation therapy in which a radioactive source is placed directly inside or next to a tumor.

  • “Brachy” = short distance; it delivers high-dose radiation locally while sparing surrounding healthy tissues.

Types

  1. Intracavitary
    • Radioactive source placed in a body cavity (e.g., cervix, uterus, vagina).
  2. Interstitial
    • Radioactive source implanted directly into tissue (e.g., prostate, soft tissue tumors).
  3. Surface (or contact) therapy
    • Applied to skin or superficial tumors.

Dose Regimens

  • High-dose rate (HDR): Short, intense doses over minutes; outpatient treatment.
  • Low-dose rate (LDR): Continuous radiation over hours to days; may require hospitalization.
  • Pulse-dose rate (PDR): Intermittent radiation pulses, combining features of HDR and LDR.

Indications

  • Gynecologic cancers: Cervical, endometrial, vaginal.
  • Prostate cancer
  • Breast cancer (partial breast irradiation)
  • Head and neck cancers
  • Selected soft tissue or skin malignancies

Advantages

  • High precision → spares nearby normal tissues.
  • Shorter treatment duration compared to external beam radiotherapy (EBRT) for HDR.
  • Can be used alone or as a boost after EBRT.

Pharmacy & Clinical Considerations

  • Radiation safety: Staff and patient exposure considerations.
  • Adjunctive therapy: Often combined with chemotherapy (e.g., cisplatin in cervical cancer).
  • Supportive care: Antiemetics, pain management, and management of local tissue reactions.
  • Monitoring: Acute and late toxicities (e.g., mucositis, urinary symptoms, proctitis).

Toxicities

  • Local: Pain, erythema, edema, ulceration, mucositis.
  • Organ-specific: Bladder irritation, bowel toxicity, vaginal stenosis (gynecologic cases).
  • Systemic: Minimal compared to external beam radiation.