The objectives of this study were to evaluate retrospectively the toxicity, LC rate, and OS rate according to the fractionation schedules: 4 or 5 8 fractions.
A second meta-analysis also including more recent trials in advanced SCCHN found an overall survival benefit of 12 months when adding chemotherapy to normally fractionated radiotherapy or even altered fractionation schedules [ 5].
Wolfson et al. also assessed the late neurotoxicity of PCI in patients with LD who achieved CR following initial treatment, comparing three doses and fractionation schedules (25 Gy in 10 daily fractions, 36 Gy in 18 daily fractions, and 36 Gy in 24 fractions twice daily).
In dose fractionated radiotherapy the effect of different fractionation schedules could have substantial relevance in clinical practice.
The dose fractionation schedules were 50 Gy in 5 fractions for the patients with lung cancer and 54 Gy in 18 fractions for those with liver cancer.
There are, for example, clinical indications for using a range of fractionation schedules (Agarawal et al, 2006) – from single doses to 10 fractions over 2 weeks – and this provides an attractive opportunity to vary the number of fractions of radiation that are sensitised by a novel agent.
Although the linear quadratic model for calculating biologically equivalent doses (BED) can be unreliable for large fraction sizes, it can provide an estimate with which to compare different fractionation schedules.
To facilitate the comparison of the different fractionation schedules used by different centers, we computed the 2-Gy per fraction biologically effective dose (BED) according to the linear-quadratic model: BED = nd(1+ [d÷α/β]); where α/β = 10 for plasmacytoma; n = number of fractions; and d = dose per fraction [ 14].
Accelerated fractionation schedules were designed to counter accelerated repopulation.
Recent research into fractionation schedules, with hyperfractionated and accelerated radiotherapy regimens has been promising.
Thus, more precise intervention will enable fractionation schedules that better interoperate with advances such as immunotherapy.
