What are the Differences Between External Beam Radiation Therapy and Brachytherapy for Prostate Cancer?

Radiation therapy is an essential part of prostate cancer treatment. The technique uses high-energy radiation to kill cancer cells and is often employed to treat localized prostate cancer. There are two main types of radiation therapy used for prostate cancer: external beam radiation therapy (EBRT) and brachytherapy.

EBRT vs. Brachytherapy for Prostate Cancer: Technique

External Beam Radiation Therapy (EBRT) is a technique where high-energy radiation beams are directed to the prostate from outside the body using a specialized machine. There are several types of EBRT, each with unique characteristics. 3D-Conformal Radiation Therapy (3D-CRT) utilizes computers to accurately map the prostate's location, allowing for the precise shaping and targeting of radiation beams from multiple directions. Intensity-Modulated Radiation Therapy (IMRT) is a more advanced form of 3D therapy that adjusts the intensity of radiation beams to reduce damage to healthy tissue. Stereotactic Body Radiotherapy (SBRT) is an ultra-precise radiation therapy method, typically delivered over a shorter period.

Brachytherapy is a method that involves implanting small radioactive pellets, known as "seeds," directly into the prostate. This technique can be categorized into two types. In Low Dose Rate (LDR) Brachytherapy, the seeds are permanently placed in the prostate, where they emit radiation slowly over several weeks to months. Alternatively, High Dose Rate (HDR) Brachytherapy involves a temporarily implanted radioactive source that delivers high doses of radiation over a short period. This procedure is generally repeated a few times before the radioactive source is removed.

EBRT vs. Brachytherapy for Prostate Cancer: Duration

EBRT typically requires daily treatments over several weeks, ranging from six to nine weeks on average. This frequency can be demanding for some patients due to the time commitment. On the other hand, LDR brachytherapy is often completed in a single outpatient procedure, with the seeds left in place to deliver radiation over time. HDR brachytherapy requires a few sessions, but these are usually completed within two days.

EBRT vs. Brachytherapy for Prostate Cancer: Side Effects and Challenges

Both methods of radiation therapy have potential side effects, but they can differ in nature and severity. The common side effects of EBRT can include fatigue, mild skin reactions, upset stomach, loose stools, and urinary and bladder symptoms. In the long term, erectile dysfunction can occur in some men. Brachytherapy, in the short term, can cause discomfort in the area of the seed implants, along with urinary symptoms such as frequency and urgency. Long-term effects can include sexual and urinary dysfunction, similar to EBRT.

External Beam Radiation Therapy has become more precise over the years with advances in imaging technology, but it still involves irradiating a certain amount of healthy tissue around the prostate. In contrast, brachytherapy delivers radiation directly to the prostate, minimizing exposure to surrounding healthy tissues. However, it requires surgical precision during seed implantation to ensure optimal targeting of the cancer.

EBRT vs. Brachytherapy for Prostate Cancer: Suitability

Not all patients are suitable candidates for both treatments. EBRT is often suitable for most men with prostate cancer, including those with larger prostates or cases where the cancer has spread to the tissues around the prostate. In contrast, brachytherapy is generally more suited to men with slow-growing prostate cancers. Men with larger prostates or existing urinary problems may not be ideal candidates for brachytherapy.

Both external beam radiation therapy and brachytherapy are effective methods of treating prostate cancer. However, the choice between them often depends on a variety of factors, including cancer stage and aggressiveness, the patient's overall health status, the potential side effects, and personal preference.

EBRT vs. Brachytherapy for Prostate Cancer: Conclusion

External beam radiation therapy with its various forms, is a non-invasive procedure suitable for a wide range of patients, including those with more advanced prostate cancers. It offers high precision and is increasingly fine-tuned to minimize damage to healthy tissue, although it still involves a longer treatment period and possible side effects. Brachytherapy, on the other hand, offers a concentrated, direct radiation delivery method that spares the surrounding tissues. It often involves fewer treatment sessions but requires a more invasive procedure for the placement of radioactive seeds.

Further Reading

  1. Stish BJ et al. Brachytherapy in the Management of Prostate Cancer. Surg Oncol Clin N Am. 2017 Jul;26(3):491-513. PMID: 28576185.
  2. Daly T. Evolution of definitive external beam radiation therapy in the treatment of prostate cancer. World J Urol. 2020 Mar;38(3):565-591. PMID: 30850855.

Disclaimer: This blog post is intended solely for informational purposes. It is not meant to serve as medical advice. For professional medical guidance, please consult your doctor. 

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