Less Radiation to Healthy Tissues
Applicable for tumors anywhere in the body, proton therapy has been used to treat prostate cancer for many years [1,2] with proven success.
Unlike traditional radiation treatments, proton therapy deposits positively charged particles of energy directly into the prostate, leaving no exit dose and lowering the risk of unnecessary exposure to healthy tissue. As such, it also allows for definitive doses of radiation while minimizing adjacent organ exposure in an effort to reduce side effects, making it particularly effective for the following indications:
Localized prostate cancer
- Reduced radiation exposure to surrounding healthy tissues , particularly the rectum and bladder , as compared to IMRT
- Excellent clinical outcomes for early stage prostate cancer following high-dose proton therapy [5-7]
- Excellent clinical outcomes and minimal toxicity following advanced proton therapy with different fractionation schedules [11,12]
Locally advanced prostate cancer
As compared to photon-based therapy, proton therapy offers:
- Reduced radiation dose to normal structures (including bladder, small bowel, and rectum) during pelvic radiation 
- Minimal gastrointestinal toxicity following treatment for prostate and pelvic lymph nodes 
Salvage treatment for local relapse of prostate cancer
- Early data of a small number of patients demonstrates a high rate of cancer control and acceptable toxicities from proton therapy for prostate cancer and local relapse following cryosurgery or HIFU 
1. Shipley, W.U., et al., Proton radiation as boost therapy for localized prostatic carcinoma. JAMA, 1979. 241(18): p. 1912-5.
2. Slater, J.D., et al., Proton therapy for prostate cancer: the initial Loma Linda University experience. Int J Radiat Oncol Biol Phys, 2004. 59(2): p. 348-52.
3. Trofimov, A., et al., Radiotherapy treatment of early-stage prostate cancer with IMRT and protons: a treatment planning comparison. Int J Radiat Oncol Biol Phys, 2007. 69(2): p. 444-53.
4. Vargas, C., et al., Dose-volume comparison of proton therapy and intensity-modulated radiotherapy for prostate cancer. Int J Radiat Oncol Biol Phys, 2008. 70(3): p. 744-51.
5. Zietman, A.L., et al., Randomized trial comparing conventional-dose with high-dose conformal radiation therapy in early-stage adenocarcinoma of the prostate: long-term results from proton radiation oncology group/american college of radiology 95-09. J Clin Oncol, 2010. 28(7): p. 1106-11.
6. Bryant, C., et al., Five-Year Biochemical Results, Toxicity, and Patient-Reported Quality of Life After Delivery of Dose-Escalated Image Guided Proton Therapy for Prostate Cancer. Int J Radiat Oncol Biol Phys, 2016. 95(1): p. 422-34.
7. Takagi, M., et al., Long-term outcomes in patients treated with proton therapy for localized prostate cancer. Cancer Med, 2017. 6(10): p. 2234-2243.
14. Widesott, L., et al., Helical tomotherapy vs. intensity-modulated proton therapy for whole pelvis irradiation in high-risk prostate cancer patients: dosimetric, normal tissue complication probability, and generalized equivalent uniform dose analysis. Int J Radiat Oncol Biol Phys, 2011. 80(5): p. 1589-600.
15. Chuong, M.D., et al., Minimal toxicity after proton beam therapy for prostate and pelvic nodal irradiation: results from the proton collaborative group REG001-09 trial. Acta Oncol, 2017: p. 1-7.
16. Holtzman, A.L., et al., Proton Therapy as Salvage Treatment for Local Relapse of Prostate Cancer Following Cryosurgery or High-Intensity Focused Ultrasound. Int J Radiat Oncol Biol Phys, 2016. 95(1): p. 465-71