Editing Radiotherapy for Prostate Cancer (section)

== Hypofractionation ==

* '''The full dose of radiation is usually divided into a number of smaller doses called fractions'''
** Fractionated radiotherapy has been used since the early days of radiation, when it was found that cure could be achieved with less normal tissue injury when the radiation dose was split into many small fractions
* '''Hypofractionation (i.e. fewer fractions) reduces the overall treatment course by delivering higher doses per fraction'''
* Prostate cancer is believed to be acutely sensitive to the amount of radiation delivered at each treatment, such that providing a few treatments of high dose is more effective at producing cell kill than many fractions of 2 Gy. 
**It is hypothesized that one could provide a lower total dose, thus lessening risk for normal organ injury, with similar prostate cancer control using higher than standard doses per fraction
**Patient risk selection and biologically effective doses have resulted in excellent biochemical control reported up to 5 years, but it is not clear if moderate hypofractionation is more efficacious.
*'''Doses in the range of 2.6 to 3.1 Gy have been delivered in phase III trials with low morbidity'''.
**Safe treatment delivery requires accurate patient setup and conformal treatment planning.
* '''Early studies of extreme fractionation (6.7 to 10 Gy) show good biochemical control rates but the duration of follow-up is limited.'''