Radiobiology 2016

1/03/2016

Head & neck

• Risk of late damage is higher in retreated patients… • But cumulative total dose for 20%

80 100

Single course N = 3635

0 20 40 60

complication rate at 5 y is higher than predicted from single course treatment (EQD2 3 = 86 vs 67 Gy) indicating partial recovery!

Reirradiation N = 487

Complication free survival (%) 0 2

4

6

8

10

Time from (re)irradiation (years)

Lee AWM et al. Int J Radiat Oncol Biol Phys 20000

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Head & neck • Summary studies by Lee AWM et al • Local control: T1>T2>T3 • Local control: EB+IRT >IRT or EBRT only

• Initial dose (calculated as EQD2) correlated significantly with late complications (α/β = 2–3 Gy) No correlation with retreatment LC (α/β = 10 Gy) • Retreatment dose (calculated as EQD2) correlated significantly with LC (α/β = 10 Gy) Borderline correlation with late complications (p = 0.54 to 0.86 for α/β = 2–3 Gy)

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