Precise Prostate Cancer Treatment with Fewer Adverse Effects – Combining MRI and Radiotherapy

Prostate cancer is the fourth most common cancer worldwide. There were 1.4 million new cases in 2020, and this number is expected to reach 29.5 million per year by 2040. Radiotherapy is a fundamental component of prostate cancer treatment, and approximately 50% of patients with prostate cancer benefit from it. However, conventional radiotherapy techniques frequently cause adverse effects such as urinary, bowel, and sexual dysfunction. A recently developed approach, magnetic resonance imaging (MRI) -guided stereotactic body radiotherapy (SBRT), aims to improve treatment quality by reducing these adverse effects.

Stereotactic Body Radiotherapy (SBRT) is a radiotherapy technique that delivers high-dose radiation to a specific tumor region using precise targeting methods. It provides effective treatment while minimizing damage to surrounding healthy tissue.

SBRT is usually delivered under computed tomography (CT) guidance. MRI-guided SBRT is a newer, more advanced technology that has begun to be used for tumors in particularly sensitive areas because it offers real-time imaging.

The MIRAGE Phase 3 Trial: Further Findings

The results were published on 13 November 2024 in European Urology . The phase 3 clinical trial called MIRAGE evaluated the long-term benefits of aggressive reduction of targeting margins with MRI guidance. The study examined 156 patients diagnosed with prostate cancer who were randomly assigned to MRI- or CT-guided SBRT. The findings can be summarized as follows:

• Urinary toxicity rates at 2 years were 27% with MRI guidance and 51% with CT guidance (p = 0.004).

• Bowel toxicity rates were 1.4% with MRI guidance and 9.5% with CT guidance (p = 0.025).

• Rates of deterioration in sexual health and bowel function were lower with MRI guidance.

These findings support the possibility that a tighter planning-margin strategy can reduce adverse effects.

Meta-Analysis Results: A Notable Reduction in Adverse Effects

A large study conducted by Dana-Farber Cancer Institute and published in July 2023 in Cancer , found that MRI-guided daily adaptive SBRT, compared with conventional computed tomography (CT)-guided SBRT, significantly reduced adverse effects . The study examined 2,547 patients from 29 different clinical studies. Its findings were as follows:

• Short-term urinary adverse effects decreased by 44%.

• Bowel adverse effects decreased by 60%.

This technology was shown to provide effective treatment while protecting critical tissues in prostate cancer. However, more data are needed on long-term effects.

Advantages of MRI-Guided Radiotherapy

The main advantages of MRI-guided radiotherapy are:

1. Real-time monitoring: It improves treatment precision by adapting to daily changes in the prostate's position.

2. Smaller targeting margins: They reduce damage to critical tissues.

3. Reduced long-term toxicity: Bowel and urinary tract toxicities decrease significantly.

4. High patient satisfaction: It improves patients' quality of life through less deterioration in sexual health and bowel function.

Conclusion and Future Perspectives

MRI-guided SBRT is an important innovation marking the beginning of a new era in prostate cancer treatment. The findings show that this technology is effective in reducing long-term adverse effects. However, cost-effectiveness analyses and larger clinical studies of its practical use are still needed. Expanding its use to other cancer types in the future could redefine treatment standards.