The Role of Radiotherapy in Mesothelioma Treatment

For many years, radiotherapy was overlooked as a treatment option for malignant mesothelioma. Early reports suggested that radiation might actually make the tumor grow faster. Fortunately, with advancements in radiation technology and research, radiotherapy has now become an important part of mesothelioma treatment, especially for symptom relief and improving survival when combined with other therapies.

Let’s explore how radiotherapy works, its effectiveness, and how it fits into modern mesothelioma treatment plans.

How Radiotherapy Works

Radiotherapy, also known as radiation therapy, uses high-energy beams (X-rays, gamma rays, or particle beams) to target and kill cancer cells. It works by damaging the DNA inside cancer cells, preventing them from multiplying.

There are two main types of radiotherapy used for mesothelioma:

1. External Beam Radiation Therapy (EBRT) – Delivers radiation from outside the body using a machine.
2. Brachytherapy (Internal Radiation Therapy) – Places a radioactive source directly inside the pleural or peritoneal cavity.

Each type has specific uses, benefits, and risks, depending on the stage of mesothelioma and treatment goals.

The Evolution of Radiotherapy for Mesothelioma

Early Experiments and Controversy

In the early 1970s, researchers began experimenting with radiotherapy for pleural mesothelioma. The first systematic trial was conducted in France (1973), where patients received radiation doses between 3,500 and 7,500 cGy. The study reported:

• Improved pain relief
• Some tumor shrinkage
• Median survival of 15 months

However, early studies had limitations, and many doctors remained skeptical.

Breakthroughs in the 1980s and 1990s

By the 1980s, larger trials in Germany and the U.S. showed similar results:

• Higher doses (4,000–6,000 cGy) helped control symptoms
• Pain relief was reported in most patients
• Survival remained limited (10–12 months on average)

One of the biggest challenges was that radiation alone couldn’t control microscopic tumor spread, making it less effective as a standalone treatment.

Modern Radiotherapy: When and How It’s Used

Today, radiotherapy is not a cure for mesothelioma, but it plays a valuable role in treatment. It is used in three key situations:

1. Post-Surgery Radiation (Adjuvant Radiotherapy)

• Used after surgery to destroy any remaining cancer cells.
• Goal: Reduce recurrence and improve survival.
• Best for: Patients who undergo extrapleural pneumonectomy (EPP) or pleurectomy/decortication (P/D).

2. Palliative Radiotherapy (Symptom Relief)

• Used to relieve pain and breathing difficulties.
• Goal: Shrink tumors pressing on nerves, lungs, or the spine.
• Best for: Patients with advanced mesothelioma to improve quality of life.

3. Preventing Tumor Seeding (Prophylactic Radiation)

• Used to stop cancer cells from spreading along biopsy or surgical sites.
• Goal: Prevent new tumor growth at these sites.
• Best for: Patients after thoracoscopy, pleural biopsy, or chest tube placement.

Advancements in Radiation Therapy

1. Intensity-Modulated Radiation Therapy (IMRT)

IMRT is a modern radiation technique that delivers precise, high-dose radiation while sparing healthy tissues. It has:

• Improved tumor targeting
• Lowered radiation damage to the lungs and heart
• Increased effectiveness when combined with surgery

A study by Sugarbaker et al. found that patients treated with IMRT after surgery had better survival rates than those who did not receive radiation.

2. Proton Therapy

Proton therapy is a newer radiation approach that uses protons instead of X-rays. It:

• Delivers energy directly to tumors without affecting healthy tissues.
• Reduces radiation damage to the lungs, heart, and spine.
• Shows promise in increasing survival for mesothelioma patients.

However, proton therapy is not yet widely available, and its long-term effectiveness for mesothelioma is still being studied.

Challenges and Side Effects of Radiotherapy

While radiotherapy has clear benefits, it also comes with risks and side effects. The biggest challenges include:

• Radiation Pneumonitis: Inflammation of the lungs caused by radiation exposure.
• Fatigue: Common in patients undergoing multiple radiation sessions.
• Skin Reactions: Redness, peeling, or sensitivity in the treated area.
• Heart or Nerve Damage: Can occur if radiation affects surrounding organs.

Doctors use advanced planning techniques like CT-guided radiation to minimize side effects and target tumors more precisely.

Combining Radiotherapy with Other Treatments

Since radiotherapy alone cannot cure mesothelioma, doctors combine it with other treatments to maximize effectiveness.

1. Surgery + Radiotherapy

• Best for: Early-stage mesothelioma.
• Strategy: Surgery removes most of the tumor, while radiotherapy kills remaining cancer cells.
• Success Rate: Some studies show 2-year survival rates of 45% in well-selected patients.

2. Chemotherapy + Radiotherapy

• Best for: Patients who are not surgical candidates.
• Strategy: Chemotherapy shrinks tumors, making radiation more effective.
• Success Rate: Improved symptom control and slightly increased survival.

3. Immunotherapy + Radiotherapy

• Best for: Experimental clinical trials.
• Strategy: Boosts the immune system while targeting tumors with radiation.
• Success Rate: Early studies suggest this may enhance treatment response.

Clinical Trials and Future Research

Radiotherapy for mesothelioma is still evolving. Researchers are testing new radiation techniques and combinations to improve survival. Some areas of focus include:

• Adaptive Radiation Therapy (ART): Uses real-time imaging to adjust radiation during treatment.
• Radiation + Gene Therapy: Aims to enhance the body’s ability to fight cancer.
• Hypofractionated Radiation: Uses higher doses over fewer sessions, reducing treatment time.

Patients should consider enrolling in clinical trials to access the latest treatment options.

Final Thoughts

• Radiotherapy has come a long way from its early controversy.
• It is not a cure but plays a crucial role in symptom relief and treatment success.
• Modern techniques like IMRT and proton therapy improve precision and reduce side effects.
• Combining radiation with surgery, chemotherapy, or immunotherapy gives the best results.
• Ongoing research is paving the way for even better treatments.

If you or a loved one is considering radiotherapy for mesothelioma, it’s important to discuss the latest options with a specialist to determine the best treatment plan for your specific case.