External Beam Radiation

External Beam Radiation Therapy: Applications, Efficacy, and Considerations

Introduction to External Beam Radiation Therapy (EBRT)

External Beam Radiation Therapy (EBRT) is a cornerstone in the treatment of various cancers and other medical conditions. It involves directing high-energy radiation beams from outside the body to target and destroy cancer cells while sparing surrounding healthy tissue. This article synthesizes recent research on the applications, efficacy, and considerations of EBRT across different medical conditions.

EBRT in Cervical Cancer

Boost in Locally Advanced Cervical Cancer

In the treatment of locally advanced cervical cancer, EBRT is often used as a boost to enhance the effectiveness of primary treatments. A review by the Gynaecology Study Group in the Italian Association of Radiation and Clinical Oncology (AIRO) analyzed 30 studies on different EBRT boost modalities. The findings indicated that high-tech EBRT was not superior to image-guided brachytherapy for delivering a boost in these cases. The review highlighted the need for prospective clinical studies to compare these modalities directly.

EBRT in Liver Cancers

Hepatocellular Carcinoma (HCC) and Intrahepatic Cholangiocarcinoma (IHC)

The American Society for Radiation Oncology (ASTRO) provided guidelines for the use of EBRT in primary liver cancers, including HCC and IHC. EBRT is recommended as a first-line treatment for patients with liver-confined HCC who are not candidates for curative therapy. It is also suggested as a consolidative therapy after incomplete responses to liver-directed therapies and as a salvage option for local recurrences. For IHC, consolidative EBRT with or without chemotherapy is recommended, particularly after systemic therapy.

EBRT in Ophthalmology

Choroidal Neovascularization (CNV)

A study on the use of EBRT for choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) found that EBRT was not effective in improving visual acuity. Patients treated with EBRT showed a significant drop in visual acuity after one year, similar to the control group, suggesting that this dose of EBRT should not be used for CNV secondary to AMD.

EBRT in Orthopaedic Pathology

Management of Musculoskeletal Conditions

EBRT plays a crucial role in managing various musculoskeletal conditions, including bony and soft-tissue sarcomas, metastatic tumors, and heterotopic ossification. The therapy helps reduce functional loss from cancer resections and is delivered using different energy types such as protons, photons, electrons, and neutrons. Each type has unique roles and limitations in treating various pathologies .

Optimization and Safety in EBRT

Dose Distribution and Radiation Protection

Optimizing EBRT involves creating dose distributions that fit the prescribed tumor contour while minimizing exposure to nearby vulnerable sites. Advanced methodologies and algorithms have been developed to study dose distribution outside the target volume, ensuring radiation protection and minimizing the risk of complications .

Long-term Sequelae in Prostate Cancer

Long-term studies on EBRT for prostate cancer have shown that while there is a low incidence of major intestinal and urinary complications, higher doses (greater than 70 Gray) significantly increase the risk of urinary complications. These findings underscore the importance of dose management in minimizing long-term morbidity.

Conclusion

EBRT remains a vital treatment modality across various medical fields, from oncology to orthopaedics. While it offers significant benefits, careful consideration of dose, technique, and patient-specific factors is essential to maximize efficacy and minimize adverse effects. Ongoing research and clinical trials will continue to refine its applications and improve patient outcomes.

Summary

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