Loss of local control with prolongation in radiotherapy

Hypofractionated accelerated radiotherapy in T1–3 N0 cancer of the larynx: A prospective cohort study with historical controls

“…Shorter RT with the same total and fraction doses as those used in conventional radiotherapy improves loco-regional control and DFS. 3,7,[26][27][28][29] This conclusion is also supported by results of meta-analysis of phase III trials that concentrated mainly on accelerated hyperfractionated protocols, published by Bourhis et al 5 Reduced total dose delivered over shorter time produced results similar to conventional RT. 15 Longer than standard treatment duration has a negative impact on outcomes of radiotherapy for head and neck cancer, with loco-regional control loss of 1.2% per day or 12-14% per week.…”

“…[1][2][3][4] It has been estimated that longer RT duration reduces local control of the tumor by 3-25% (median 15%) after 1 week and 5-42% (median 26%) after 2 weeks prolongation. 5 If RT delivery is shortened by 1 week, outcome improves by up to 9%. 6,7 Meta-analysis of trials comparing conventional RT to hyperfractionated and/or accelerated RT for head and neck cancer found a 5-year survival benefit of 3.4% that was higher with hyperfractionated radiotherapy (8%) than with accelerated radiotherapy (1.7-2%).…”

Intensity-Modulated Radiotherapy for Nasopharyngeal Carcinoma: Penang General Hospital Experience

“…One report that did state this rate was a Hong Kong study involving 50 patients that showed a similar rate of 92% completing the IMRT treatment without requiring a treatment break (Kwong et al, 2006).Our completion rate within the stipulated OTT is very encouraging in view of the importance of completion of radical RT within the 7 weeks time frame as studies have estimated a loss of approximately 1.4% local control for every day of delay beyond the OTT. This will translate to a loss of 10-12% of local control with a delay of one week during treatment (Maciejewski et al, 1983;Vikram et al, 1985;Maciejewski et al, 1989;Barton et al, 1992;Fowler et al, 1992). This effect is most likely due to proliferation of surviving clonogenic tumour cells between dose fractions and it is most prominent between the 3 rd and 7 th week of conventional RT of head and neck cancers.…”

Avoidance of treatment interruption: an unrecognized benefit of accelerated radiotherapy in oropharyngeal carcinomas?

“…Based on evidence suggesting that increasing overall treatment time (OTT) is detrimental to locoregional control, accelerated RT programs have been intensively investigated during the past two decades. However, most clinical data regarding the importance of OTT came from series using conventionally fractionated RT, where treatment interruptions constituted the main cause of prolonged OTT (3,4). Besides considerably shortening OTT, accelerated schedules may also be associated with the potential advantage of minimizing treatment interruptions (1,5).…”