Hypofractionated radiation therapy comparing a standard radiotherapy schedule (over 3 weeks) with a novel 1-week schedule in adjuvant breast cancer: an open-label randomized controlled study (HYPORT-Adjuvant)—study protocol for a multicentre, randomized phase III trial

Table 5 Table showing the radiobiological calculations for the biologically equivalent doses (BED) of dose schedules to be used for the trial assuming different scenarios for the α/β ratio for breast tumour

Parameters	Mastectomy		Breast conservation (with SIB)
Parameters	Standard	Experimental	Standard	Experimental
Dose (Gy)	40	26	48	32
Dose per fraction	2.67	5.2	3.20	6.4
BED (Gy_2.5)	82.7	80.8	109.4	113.9
BED (Gy₃)	75.6	71.1	99.2	100.3
BED (Gy_3.5)	70.5	64.6	91.9	90.5
BED (Gy₄)	66.7	59.8	86.4	83.2
For brachial plexus only (SIB used only for breast tumour bed—not for SCF)
BED (Gy₂)	93.3	93.6	NA	NA
BED (Gy_1.5)	111.11	116.13	NA	NA

Note that for normal tissue reactions, the α/β ratio is more well defined at 3–3.5. Gy3, Gy3.5 and Gy 4 represent the BED calculations assuming the α/β ratio of 3, 3.5 and 4, respectively. The dose calculations for breast conservation are for the volume receiving SIB. If a sequential boost of 12 Gy in 4 fractions is given, then the BED values are 99.6 Gy₃, 92.8 Gy_3.5 and 87.7 Gy₄

ISSN: 1745-6215