Radiation Therapy for Cancer: Treatment Frequency and Delivery Methods

The number of radiation treatments varies widely based on cancer type, stage, intent (curative vs. palliative), tumor location, and patient health. Courses range from a single fraction to 30–35 fractions over 6–7 weeks.

External Beam Radiation Therapy (EBRT)

Delivers high-energy photons or protons from a linear accelerator. Typical regimens:

• Curative: 1.8–2.0 Gy per fraction, 5 days/week, total 50–70 Gy (25–35 fractions).
• Palliative: 1–10 fractions (e.g., 8 Gy × 1 for bone metastases).
• Stereotactic body radiation therapy (SBRT): 1–5 high-dose fractions for small, well-defined targets.

Brachytherapy (Internal Radiation)

Radioactive sources placed directly into or near the tumor.

• Low-dose-rate (LDR): Permanent seeds (e.g., prostate) or temporary implants over hours–days.
• High-dose-rate (HDR): Temporary catheter-based delivery in multiple sessions.

Systemic Radiation

Used for hematologic malignancies (e.g., total body irradiation before stem cell transplant) or targeted radionuclide therapy (e.g., I-131 for thyroid cancer).

Radiation is often combined with surgery, chemotherapy, or immunotherapy. A multidisciplinary team tailors the plan to the individual.