How low is the α/β ratio for prostate cancer?

What do we know about the α/β for prostate cancer?

“…8 Several recent studies have reported low a/b values for prostate cancer. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] If this a/b is proven to be lower than values estimated for late complications, then hypofractionated regimens are expected to improve the therapeutic ratio, 8,[29][30][31][32][33][34][35][36] beyond the advantages on cost saving and patient convenience.…”

“…Nevertheless, the question of how low the a/b ratio for prostate cancer is remains unanswered, [37][38][39] and many factors have been reported to contribute to the uncertainty about estimations of its value, such as heterogeneity of tumors 10,40 and interpatient variations, 41,42 influence of hypoxia, 42 onset of clonogenic cells repopulation, 15,17,26,41,43,44 repair during lowdose-rate brachytherapy (LDRBT), 11,15,17,26,41,44 value of the relative biological effectiveness (RBE) of permanent implants, 14,41,44,45 variations with clinical stage, [24][25][26][27]42 edema resulting from the insertion of radioactive seeds into the prostate, 17 dose heterogeneity of brachytherapy (BT) implants, 23,41 biological effectiveness of external-beam radiotherapy (EBRT) and LDRBT, 46 relevance of parameters determined in vitro and its relation to the in vivo environment, 18,42,47 use of combined data from multiple institutions with different modalities, 13 and imprecision of data assessed with only one modality. 20,23,27 Therefore, despite large evidence exists in favor of a low a/b ratio, caution must be taken when designing hypofractionated schedules, as small differences in its value may lead to marked changes in th...…”

Radiobiological Modelling in Radiation Oncology

“…The debate regarding the most appropriate α/β ratio for prostate cancer (Brenner and Hall 1999;Fowler et al 2003;Wang et al 2003;Kal and van Gellekom 2003;Nahum et al 2003;Valdagnia et al 2005) is a classic example of the challenges associated with radiobiological modelling. Previously it has been assumed that prostate tumours have high α/β values, similar to most other tumours and early reacting normal tissues.…”

Monte Carlo simulation of modern techniques of intensity modulated radiation therapy (IMRT)

“…We conducted a custom literature search in order to collect measured or calculated α, β and α/β ratios for different cell types and organs versus energy [103][104][105][106][107][108][109][110][111][112][113]. The goals was to link differences of SER and RBE values versus energy, and explain discrepancies between the calculated and simulated DERs and the measured RBE and SER of different cell lines.…”

“…The goals was to link differences of SER and RBE values versus energy, and explain discrepancies between the calculated and simulated DERs and the measured RBE and SER of different cell lines. Energy ranges varied from low dose rate brachytherapy sources (I-125 and Pb-103) [104,110,112], high dose rate brachytherapy sources (Ir-192) [108], 250 kVp x-ray sources [103,113], external MV beams [105 -107, 109, 111, 112]. All these studies used different cell lines, organs and tissues both from humans and animals.…”