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Results of a UK survey on methods for compensating for unscheduled treatment interruptions and errors in treatment delivery

¹ Hammersmith Hospitals NHS Trust, London W6 8RF, ² Faculty of Medicine, Imperial College, London SW7 2AZ, ³ Queen Elizabeth University Hospital, Birmingham B15 2TH, UK

Correspondence: Professor R G Dale, Radiation Physics & Radiobiology, Charing Cross Hospital, London W6 8RF, UK. E-mail: r.dale{at}imperial.ac.uk

	Abstract

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In order to obtain a preliminary overview of the current national status regarding the management of both unintentional interruptions to radiotherapy treatments and inadvertent errors in treatment delivery, a short questionnaire was sent to 60 UK radiotherapy departments, of which 35 (58%) responded. The study was initiated by the authors and was not commissioned by any professional body. Amongst the centres which responded the majority (86%) currently have standardized protocols in place for dealing with treatment interruptions and many have extended the enactment of compensation methods to cover a wider range of tumour types than are encompassed within the Royal College of Radiologists (RCR)-defined Categories 1 and 2. Fewer of the respondents (60%) have standardized methods for dealing with treatment errors. Given that 42% of centres did not respond it is difficult to assess the fuller national picture. Some smaller departments may seek protocols or advice from larger adjacent centres, but the overall percentage of centres with systems in place may be lower than indicated from the survey results. The desirability of providing training in the radiobiological methods pertaining to treatment compensation was raised by a number of respondents.

	Introduction

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General guidelines on the principal methods available for dealing with unscheduled treatment interruptions were first published by the Royal College of Radiologists (RCR) in 1996 and were updated in 2002 [1]. More detailed guidance on the radiobiological significance of tumour repopulation during treatment, and an extensive review of the clinical evidence for the resulting detriment, was provided in articles published at around the same time as the RCR guidelines [2, 3]. There is growing evidence to indicate that some tumours (especially squamous cell carcinomas, SCCs) repopulate very rapidly towards the end of treatment [4, 5] and that has highlighted the importance of adhering to the overall treatment times set out in prescribed treatment schedules and of the likely detriment (in terms of tumour control) that can be caused if treatments are unnecessarily extended.

In April 2005, a survey was conducted to determine the degree of national awareness of the significance of unscheduled interruptions and to obtain preliminary information about the extent to which local compensation procedures are in place. Comments were also invited on what, if any, general measures were required to improve the understanding of how to approach radiobiological compensations. Since the radiobiology relevant to devising treatment gap compensations is similar to that required for correcting errors in treatment delivery, additional information was sought in relation to the latter.

	Methods and materials

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A questionnaire was devised by the authors and circulated to the head of radiotherapy physics in 60 departments. A covering letter requested that, if it were more appropriate, the questionnaire should be passed on to another senior radiotherapy colleague for attention. Altogether 35 replies were received, a response of 58.3%.

	Results

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The questions asked are given here (in italics), along with the answer summaries. Answers are expressed as a percentage of the 35 centres that responded.

Questions
Part A: General
A1) Please indicate (approximately) the percentage of all RT treatments performed in your Centre which are subjected to an unscheduled interruption.

5 (median)

A2) Are the following staff in your Centre aware of the potential clinical impact of unscheduled treatment interruptions?

D2) If the answer to (B1) or (C1) is YES, please indicate below if your department ever faces significant problems in carrying out the necessary radiobiological assessments.

The comments and suggestions (and the number of Centres making them) were:

	Discussion

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Only 23 (66%) of the centres that responded were able to put a figure on the percentage of radiotherapy treatments subjected to an unscheduled interruption. With the exception of one very high value quoted by one centre, figures were in the approximate range 1–10%, with an average of 3.1% and median of 5%. 14% of the responding centres do not have methods available for the revision of interrupted schedules. This is a comparatively high figure and, given that 25 centres did not respond to the questionnaire, the overall position could be worse than suggested here. In 2002 the RCR [1] reported that a very similar percentage (13%) of centres contacted at that time had been unable to introduce any policy due to local circumstances. The results of this current survey seem to indicate therefore that little or no progress has been made since 2002 even though awareness of the potential clinical impact of unscheduled treatment interruptions appears to be uniformly high amongst clinical oncologists, radiographers and physicists in the responding centres. Some respondents were unable to say whether or not their hospital administrators had similar awareness; the overall response indicated that most administrators do not.

With regard to scheduled treatment interruptions, RCR (2002) recommends that the overall treatment time of Category 1 patients in particular should not be extended as a result of Public Holidays, Statutory Days etc. Around 9% of the respondents do not comply with the RCR guidelines in this respect, slightly fewer than the 14% of respondents that have no agreed procedures in place for revising treatment schedules (i.e. 3 and 5 centres, respectively, out of the 35 respondents). Given the greater latitude for the planning and execution of compensation for predictable breaks, it is perhaps surprising that this difference isn't greater, although lack of resources or expertise could affect the response to both types of break in treatment to a similar extent.

Part B answers
Part B sought specific information about whether compensation procedures are in place for treatment interruptions and about the personnel responsible for enacting them.

The number of responding centres without agreed procedures in place for compensating for unscheduled treatment interruptions was around 9%. Question B1 was intended to assess the number of centres employing a systematic approach to dealing with unscheduled treatment interruptions, rather than simply assessing whether compensating for gaps in general terms was accepted practice. However, with hindsight, the wording of Question B1 is perhaps too similar to that of question A3 although, interestingly, these questions produced different responses. B1 elicited a more positive response than A3, with an additional two centres indicating that they had compensation procedures available for unscheduled treatment interruptions.

Radiographers were given as being the most likely staff group to be responsible for enacting procedures to compensate for unscheduled treatment interruptions. However, in Part C, physicists were identified as being the staff group primarily responsible for enacting compensation measures for errors in treatment delivery. This is discussed further in the next section.

Ideally all centres would have at least one functional standby unit but, when set against (until very recently) a national history of chronic underinvestment in radiotherapy treatment equipment relative to the rest of Europe [6], the figure of almost 26% amongst the responding centres is perhaps higher than might have been expected. On the other hand, a few of the centres who responded "yes" to this question did have reservations about how useful their back-up units were on account of their age, poor condition, inappropriate beam energy etc.

Part C answers
Part C sought specific information about whether compensation procedures are in place for errors in treatment delivery and about the personnel responsible for enacting them.

The percentage of responding centres without procedures for compensating for errors in treatment delivery was 40%. Yet, although radiographers were said to be the main staff group responsible for enacting compensation procedures for unscheduled treatment interruptions in Part B (71.4%), in answer to a similar question in Part C it would appear that physicists and clinical oncologists are more likely to be involved in enacting error compensation methods (31.4% and 14.3%, respectively, compared with 20% for radiographers). These differences are surprising since the methods for dealing with treatment interruptions and errors in treatment delivery are very similar because the radiobiological considerations to be addressed in each case are the same. Compensation for both can be achieved via changes to one or more of the following: the number of fractions treated each day, dose per fraction and total number of fractions treated. Any calculations required will therefore follow a similar pattern in each case so it is not clear why the above differences exist.

Again, with hindsight, it may be that asking questions about who is primarily responsible for "enacting" the procedures was ambiguous. We intended to identify which staff group undertakes the ensuing calculation process, rather than who first realizes that a correction is necessary. This ambiguity might have contributed to the observed differences in response to the questions in Parts B and C.

Part D answers
Part D sought to identify the tumour sites for which compensation for interruptions is considered to be routinely necessary. It also asked if any problems had been identified in performing the radiobiological assessments and, if so, sought suggestions for resolving them.

A majority of the responding centres routinely apply compensation to interrupted treatments of the RCR-defined Category 1 (high risk and fast repopulating) cancers, indicated by asterisks in the above list. However, a significant number apply the same considerations to a selection of other cancers that are not defined as Category 1 and that are associated with lower repopulation rates.

23% of centres experience significant problems in carrying out the radiobiological assessments and a greater number (31%) suggest that some help would be useful. Once again, given the number of non-responders, the overall national situation may be rather worse than indicated here.

General discussion
Of the 35 centres that responded, 3 did not have systems in place for dealing with treatment gap corrections (see Question B1). As 25 centres did not respond, one corollary is that as many as 28 (47%) of the UK radiotherapy centres may not have a system in place, but it is not possible to speculate further on the exact figure. In dealing with unintended treatment errors the situation is potentially of even greater concern, with only 21 centres with procedures definitely in place (see Question C1), i.e. there may be as many as 39 (65%) with no procedures.

Several of the respondents made comments (either in the questionnaire or by subsequent telephone call) concerning the lack of training in how to perform treatment compensations. It is often assumed that radiotherapy physicists in particular have received some specialized radiobiological insight as a result of their post-graduate training, but in practice this is rarely the case. Although it is usually true that physicists can perform the necessary radiobiological calculations and may devise programs or spreadsheets to speed the process, there may be significant shortcomings in their knowledge of parameter values and in their background appreciation of the subtleties and caveats which need to be applied in such calculations. If such issues could be satisfactorily addressed in appropriate training programmes then the execution of radiobiological compensation methods need not be seen as being the province of any particular staff group, particularly as the calculation steps are generally fairly straightforward and usually do not require advanced mathematics.

The training of clinical oncologists is rather more satisfactory in this regard as the Part I FRCR examination questions frequently pose simple correction problems. (Worked examples of these and similar problems are published elsewhere [7, 8]). Although this approach is not without its own limitations, it nevertheless brings in a degree of practical appreciation of radiobiology which is currently absent from most medical physics and radiography degrees.

Another suggestion would be to set up a centralized national service for handling radiobiological queries and which could advise each centre, collect data and ensure uniformity of approach. This could be a virtual system but careful consideration would need to be given to issues related to clinical governance etc.

	Conclusions

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The survey results indicate that, on average, just over 3% of all radiotherapy treatments are subject to an unscheduled interruption. The figure is higher in some individual centres, probably as a result of local circumstances, e.g. those relating to location and accessibility, which may further accentuate the problems which commonly contribute to the occurrence of "missed" treatment. About 125 000 patients receive some form of radiotherapy in the UK each year. Therefore, assuming that around 90% of these receive external beam treatment, it follows that at least 3500 of them are subject to an unintended interruption. Bearing in mind the relatively high number of non-respondents in this current exercise the figure may be considerably higher. This survey did not seek information relating to the number of treatments associated with an error in delivery.

There appears to be a need for improved training in practical aspects of radiobiology on formal educational courses and perhaps also for the establishment of specialized short courses for all radiotherapy staff groups. Consideration should be given to providing the latter at fairly regular intervals and they should be aimed at addressing the issue of correcting for treatment errors as well as how to deal with scheduled interruptions. Such courses should also seek to provide updates on the essential radiobiological parameters. We further suggest that a more refined national survey be conducted after some of the training issues have been addressed. Given the large numbers of patients for whom some form of compensation is implemented there may be scope for more detailed analysis of the techniques adopted and of the long-term clinical implications of interrupted treatments.

	Acknowledgments

 
The authors wish to thank all the survey respondents, many of whom took the time to proffer additional helpful comments regarding their own local experiences in this area.

Received for publication July 13, 2006. Revision received September 21, 2006. Accepted for publication September 25, 2006.

	References

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1. Royal College of Radiologists. Guidelines for the management of the unscheduled interruption or prolongation of a radical course of radiotherapy, 2nd edn. London: The Royal College of Radiologists, 2002
2. Hendry JH, Bentzen SM, Dale RG, Fowler JF, Wheldon TE, Jones B, et al. A modelled comparison of the effects of using different ways to compensate for missed treatment days in radiotherapy. Clin Oncol 1996;8:297–307.[CrossRef]
3. Dale RG, Hendry JH, Jones B, Robertson AG, Deehan C, Sinclair JA. Practical methods for compensating for missed treatment days in radiotherapy, with particular reference to head and neck schedules. Clin Oncol 2002;14:382–93.[CrossRef]
4. Roberts SA, Hendry JA. The delay before onset of accelerated tumour cell repopulation during radiotherapy: a direct maximum-likelihood analysis of a collection of worldwide tumour-related datasets. Radiother Oncol 1993;29:69–74.[CrossRef][Medline]
5. Fu KK, Pajak TF, Trotti A, et al. A Radiation Therapy Oncology Group (RTOG) Phase III randomised study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas: first report of RTOG 9003. Int J Radiat Oncol Biol Phys 2000;48:7–16.[CrossRef][Medline]
6. Bentzen SM, Heeren G, Cottier B, Slotman B, Glimelius B, Lievens Y, et al. Towards evidence-based guidelines for radiotherapy infrastructure and staffing needs in Europe: the ESTRO QUARTS project. Radiother Oncol 2005;75:355–65.[CrossRef][Medline]
7. Dale RG, Jones B. Mathematical modelling and its applications in radiation oncology. In: Price P, Sikora K, editors. Treatment of cancer, 4th edn. London: Arnold, 2006:67–80
8. Jones B, Dale, RG, Deehan C, Hopkins KI, Morgan DA. The role of biologically effective dose (BED) in clinical oncology. Clin Oncol 2001;13:71–81.

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