Interstitial Prostate Brachytherapy

• Implantation of small radioactive sources into the prostate gland
• Recommended initial therapeutic strategy for patients with low-risk prostate cancer
  • Difficult to perform in patients with very small or very large prostates, bladder outlet obstruction symptoms, or previous transurethral resection of the prostate (TURP)
• Recommended doses:
  • 120 Gy (palladium)
  • 140 Gy (125I) with postoperative dosimetry

Low Dose-Rate Brachytherapy

• Uses permanent low-energy seeds (Iodine-125, Palladium-103) for implantation that delivers adequate doses
• Recommended for patients with low-risk disease
• May be given to patients with intermediate risk together with external beam radiation therapy (EBRT)
• Recommended dose:
  • Iodine-125: 145 Gy [110 Gy with 40-50 Gy external beam radiation therapy (EBRT)]
  • Palladium-103: 125 Gy [90-100 Gy with 40-50 Gy external beam radiation therapy (EBRT)]

High Dose-Rate Brachytherapy

• Uses temporary radioactive sources (eg Iridium-192) inserted into different locations in the prostate gland
• Recommended for patients with intermediate- to high-risk localized or locally advanced prostate cancer
• Usually given together with external beam radiation therapy (EBRT) [40-50 Gy]
• Recommended dose:
  • Monotherapy: 13.5 Gy x 2 fractions
  • With external beam radiation therapy (EBRT): 9.5-11.5 Gy x 2 fractions; 5.5-7.5 Gy x 3 fractions; 4-6 Gy x 4 fractions

External Beam Radiation Therapy (EBRT)

• Recommended initial therapeutic strategy for patients with low-high risk prostate cancer
• Should be reconsidered in patients with very low-risk prostate cancer with life expectancy of >10-20 years
• Limited radiation fields are preferred over extended field radiotherapy for localized and locally advanced prostate cancer
• Localization of prostate with image-guided radiation therapy (IGRT) is necessary with either 3-dimensional conformal radiation therapy (3D-CRT) or intensity-modulated radiation therapy (IMRT) for reducing target margin and ensuring treatment accuracy
• Recommended dose for patients with low-risk prostate cancer is 75.6-79.2 Gy; intermediate- to high-risk and metastatic prostate cancer is 81.0 Gy

Radiopharmaceutical Therapy

• Eg Radium-223 dichloride, ß-emitting agents (Strontium-89, Samarium-153)
• Option for palliative treatment of patients with metastatic disease

Beta-Emitting Radioactive Agents

• Eg Strontium-89 (Sr-89, 89Sr), Samarium-153 (Sm-153, 153Sm)
• Used for treatment of painful bone metastases

Radium-223 dichloride

• An alpha particle-emitting radioactive agent used for metastatic castration-resistant prostate cancer (CRPC) with symptomatic bone metastases but without visceral involvement
  • Studies have shown that patients given Radium-223 had better overall survival and time to appearance of symptomatic bone events than those given placebo