Editing Radiotherapy for Prostate Cancer (section)

== Heavy-particle therapy ==
* Another form of 3D-CRT
* Difficult to produce and control
* '''Theoretical advantages''' over conventional x-ray and electron beams:   
*# '''More densely destructive in tissue''', and the damage they create is less easily repaired by tumour cells
*# '''Can be easier to spare the normal tissues surrounding the cancerous target'''.
*#* Travels differently in tissue and exhibits a Bragg peak, which refers to a sharp cutoff in dose at the end of the particle’s range in tissue. Beyond this depth, the tissue receives little or no radiation.
* '''Most commonly used particles are neutrons and protons'''
** '''Neutrons'''
*** May cause more normal tissue damage than photon beam therapy
*** Few prostate cancer patients in the USA are treated with neutron RT
** '''Protons'''
*** '''An expensive treatment option for prostate cancer that currently has not demonstrated a clinical benefit over standard IMRT.'''
**** Studies comparing proton therapy to modern IMRT for prostate cancer are mostly limited to treatment-planning studies which have shown that proton radiation can reduce the volumes of nearby organs that receive low to medium—but not high—doses of radiation compared to IMRT
**** Unknown if
***** Lowering of low-to-moderate doses of radiation to the rectum from proton therapy results in lower GI toxicity rates compared to IMRT
***** Protons cause higher rates of GU toxicity or pelvic fracture rates as a result of somewhat higher doses to the bladder (at high dose regions) and femoral heads
**** No clinical study has directly compared patient outcomes
***** Data suggest that proton therapy is safe and effective for prostate cancer treatment and likely results in cancer control and morbidity outcomes similar to that with IMRT.