Radiation Therapy

Radiation therapy uses high-energy beams to destroy cancer cells. It is often used after surgery to lower the risk of cancer coming back. It can be used alone or combined with surgery, chemotherapy, or hormone therapy. When given after surgery, it is called adjuvant radiation therapy.

Types of Radiation Therapy

• External Beam Radiation Therapy (EBRT): The most common method, using a machine (linear accelerator) to direct radiation to the affected area.
  • Treatment is typically given five days a week for three to six weeks, though shorter one-week schedules may be an option.
• Brachytherapy (internal radiation): Radioactive pellets or seeds are placed inside the breast near where the tumour was, delivering a higher dose to a smaller area over a shorter period.
• Intraoperative Radiation Therapy (IORT): A single high-dose radiation treatment delivered during surgery after the tumour is removed, reducing overall treatment time.

Radiation therapy is often recommended after breast-conserving surgery (lumpectomy) to reduce the risk of recurrence. It may also be used after a mastectomy if cancer was found in the lymph nodes or surrounding tissues.

When is Radiation Therapy Recommended?

• After Lumpectomy: To eliminate remaining cancer cells and lower recurrence risk
• After Mastectomy: If cancer is large or has spread to lymph nodes
• Before Surgery (Neoadjuvant Therapy): To shrink tumours
• For Recurrence: If cancer returns in the breast or chest area
• For Metastatic Breast Cancer: To relieve symptoms and control disease spread

Planning and Treatment

Before starting radiation, a planning session (called a simulation) helps map the treatment area using imaging scans. Small tattoos or skin marks may be made to ensure consistent positioning for each session, improving accuracy and minimizing damage to healthy tissue.

Side Effects of Radiation Therapy

Short-Term Side Effects

• Skin reactions: Redness, peeling, and soreness, similar to a sunburn
• Fatigue: Common and may persist for several weeks post-treatment

Long-Term Side Effects

• Breast Changes: Treated tissue may feel firmer, shrink slightly, or look darker over time
• Lymphedema: Swelling in the arm or chest area, especially if lymph nodes were treated

Rare Side Effects

• Rib Fracture: Radiation may weaken nearby ribs
• Heart Problems: Radiation to the left chest may increase heart disease risk
• Lung Inflammation (radiation pneumonitis): May cause shortness of breath, dry cough, or mild fever, usually improving with medication

Advancements in Radiation Therapy

Recent advancements have improved the precision and convenience of radiation therapy, reducing treatment time and side effects.

Accelerated Partial Breast Irradiation (APBI)

APBI shortens treatment by targeting only the area around the tumor site instead of the entire breast. This reduces radiation exposure to healthy tissue and allows for a shorter overall treatment duration.

Stereotactic Radiation Therapy

Stereotactic radiation therapy is a very precise form of radiation used primarily for metastatic breast cancer, especially when it spreads to the brain. It delivers focused radiation to tumours while minimizing damage to surrounding healthy tissue. Two common systems for delivering stereotactic radiation include:

• Gamma Knife Radiosurgery: A non-invasive procedure that uses multiple beams of radiation to precisely target brain tumours, often completed in a single session.
• CyberKnife Robotic Radiosurgery: Uses real-time imaging to track tumour movement, allowing radiation to be delivered with extreme accuracy to the brain, lungs, spine, or liver. Treatment typically requires one to five sessions.

Stereotactic radiation therapy offers benefits such as fewer treatment sessions, reduced side effects, and can sometimes be used more than once in the same area if needed. It is available at select cancer centers and may be considered for patients with metastatic disease.

Medical Review by Roochi Arora, MD, FRCPC, August 2025

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