Hypo Fractionated Versus Conventional IMRT in Unfavorable Intermediate- and High-Risk Prostate Cancer: A Phase II Comparative Study of PSA Kinetics and Dosimetric Outcomes

The incidence rate of prostate cancer is rapidly increasing, and it has become the most prevalent solid tumor diagnosed in men.

In most cases the prostate cancer is organ-confined at the time of initial diagnosis . Radical prostatectomy and radiotherapy, either given as a seed implant or external beam radiation therapy, are the accepted standard options for treating the primary tumor itself, and androgen deprivation may be added selectively for certain cases with an intermediate or high risk of dissemination based on clinical and pathologic features evident at the time of diagnosis.

Regarding the specific option of external beam radiotherapy, the current widely accepted standard regimen for organ-confined prostate cancer involves approximately eight weeks of fractionated treatments with a daily dose of 1.8-2.0 Gy to a total dose in the range of 70-80 Gy .

Over the last decade, there have been three major advances in the use of external RT for the management of clinically localized prostate cancer: (a) androgen deprivation therapy ; (b) image-guided ration therapy with three-dimensional conformal radiotherapy and intensity modulated radiotherapy , and particularly c) radiation dose escalation schedules compared with conventional 70-80 Gy (2 Gy per fraction), which has been shown to improve biochemical and distant metastases control with minimum toxicity, but not overall survival .

The rapid dose gradients, which are able to be generated with Intensity Modulated Radiation Therapy have been demonstrated to reduce OAR dose relative to three-dimensional conformal radiotherapy resulting in well-established reductions in toxicity in the conventionally fractionated, dose escalated prostate cancer radiotherapy setting .