Effect of Hypofractionation on Prostate Cancer Radiotherapy

Abstract

Context: Prior research over the past few decades has shown that the hypofractionated external beam radiation therapy could be a valuable method with an outstanding potential to treat the prostate cancer. The alpha-beta ratio (α/β) is an indication of the fractionation sensitivity of a particular cell type. Values of α/β ≥ 10 Gy are responsible for early-responding normal tissues and most tumors, while values of α/β < 5 Gy are for late-responding normal tissues. The α/β ratio could be raised by either a local tumor control increase or a decrease of normal tissue late effects through the application of an unconventional fractionation schedules. Evidence Acquisition: This review article aimed to investigation the details of radiobiological and clinical trials which are reported to highlight the characteristics of hypofractionation for the prostate cancer treatment based on the investigation of clinical results from hypofractionated treatments. Results:With the sufficient radiobiological and physiological research studies, it may be claimed that if α/β value for prostate cancer is less than the adjacent surrounding organs at risk and by applying fewer and larger fractions; a better therapeutic ratio can be achieved for the patient. Conclusions: Radiobiological modeling can play a major role in the design of new protocols. Also, one should be aware that in modeling the hypofractionated treatment, normal tissue iso-effects are significantly important and some assumptions needed to be made regarding α/β values for the critical normal tissue complication endpoint.

Exploring breast and prostate cancer RNA-seq derived radiosensitivity with the Genomic Adjusted Radiation Dose (GARD) model

“…Limiting radiotoxicity to proximal normal prostate tissue is not considered in clinical practise, and so the variations in tumour-normal RSI determined for each patient in the prostate cancer cohort are not in any way actionable, other than pointing to clearly differing radiobiological conditions between both tissue types. The majority of patients in the prostate cancer cohort show tumour RSI values in excess of 0.4, which has been previously proposed as being a threshold indicating suitability for hypofractionation [31] , [32] ( Supplementary FigureS4 ). Many of these same patients were also identified as likely requiring a higher prescribed dose to achieve optimal GARD for tumour control in our study ( Fig.…”

In Curative Stereotactic Body Radiation Therapy for Prostate Cancer, There Is a High Possibility That 45 Gy in Five Fractions Will Not Be Tolerated without a Hydrogel Spacer

“…1 The rectum was defined as the portion within 1 cm craniocaudal to the PTV. 2 Dx% means the lowest dose of x% receiving the highest dose in the target. 3 Vx Gy means the volume of the organ receiving x Gy or more.…”

“…It is generally known that the α/β ratio of prostate cancer is low [1,2], which has led to hypofractionation in radical external beam radiation therapy (EBRT) for prostate cancer. Moderately hypofractionated EBRT with a single dose of 2.4-4 Gy has been shown to be non-inferior to conventionally fractionated EBRT in several studies [3][4][5][6], making it an alternative option to conventionally fractionated EBRT.…”

Injection of hydrogel spacer increased maximal intrafractional prostate motion in anterior and superior directions during volumetric modulated arc therapy-stereotactic body radiation therapy for prostate cancer

“…Intensity modulated radiation therapy (IMRT) with image-guided radiation therapy (IGRT) technique is currently the gold standard for EBRT. A low α/β ratio of PCa has encouraged hypofractionation and stereotactic body radiation therapy (SBRT), or extreme hypofractionation, which is currently considered as a promising option of EBRT [3][4][5][6]. Recently, the trial of the single-fraction SBRT for localized prostate cancer under the intrafractional tracking was reported [7].…”