Stereotactic body radiotherapy: A survey of contemporary practice in six selected European countries.

To the Editor, Technological advances in radiotherapy have led to increased interest in the use of high-dose treatments given in only a few fractions to try and exploit favorable anti-tumor effects...


Supplementary material available online
Supplementary Technological advances in radiotherapy have led to increased interest in the use of high-dose treatments given in only a few fractions to try and exploit favorable anti-tumor effects of hypo-fractionation. The class of treatments combining extra-cranial location, high dose, more extreme hypo-fractionation, organ at risk avoidance/sparing and a high level of accuracy is often referred to as stereotactic body radiotherapy (SBRT) [1]. It requires appropriate equipment, the relevant personnel with adequate training and expertise, and careful patient selection.
Despite several previous surveys [2 -4], a substantial number of unknowns remain concerning the contemporary practice of SBRT, especially within Europe. There is, for example, limited information about the numbers of patients that have been treated with SBRT, approaches to implementation, attitudes towards the evidence base, resource utilization and reimbursement. We therefore performed a survey of SBRT practice in six selected European countries.
committee approval was not sought, however, the email indicated that sending a reply implied consent for anonymous presentation and/or publication. The fi nal survey consisted of 10 sections and was sent to a total of 45 centers (Germany ϭ 16, Netherlands ϭ 12, England ϭ 8, Belgium ϭ 4, Denmark ϭ 3 and Austria ϭ 2) between May and September 2012. A full list of the questions is provided in the Supp lementary Appendix (available online at http://informahealthcare.com/doi/abs/ 10.3109/0284186X.2014.1003961). Data was analyzed using simple summary/descriptive statistics. In some cases multiple possible  Did you start SBRT within a prospective trial?
Did your institution practice cranial stereotactic radiotherapy / radiosurgery prior to starting SBRT?

Material and methods
To try and maximize the response we limited the survey to centers in six countries, selected using several factors, including: authors ' own countries, practi tioners known to authors and institutional track-record. All centers had at least one year SBRT experience. Emails were sent to one or more named persons in each department outlining the purpose of the survey, which was attached as an Excel document (Microsoft ® Offi ce). To assist with replies and to try and obtain more uniform data, drop-down menus were used where possible. For lung SBRT pre-treatment staging included whole-body FDG-PET/CT at 27/30 centers and 17/29 routinely performed EBUS/EUS mediastinal staging. Twenty-four of 30 centers would offer SBRT for early-stage primary NSCLC without histological confi rmation. A total of 23/30 centers were treating centrally located tumors (defi ned as within 2cm of central mediastinal structures). In total 29/30 centers were using risk-adapted fractionation schemes. Nine of 30 centers were performing FDG-PET/CT for follow-up. Out of the 27 centers treating lung metastases, 19 would treat a maximum of 1 -3 lesions (1 lesion ϭ 1 center; 2 lesions n ϭ 4; 3 lesions n ϭ 14), and eight would treat more (5 indicated they would treat up to 5 lesions), with at least two using sequential treatment above three lesions. In total 26/30 centers used heterogenous dose within the target volume. A wide variety of prescription methods and maximum acceptable target volume dose were reported. 22/30 centers indicated that they used respiratorycorrelated imaging for treatment planning of moving targets. In at least four of the cases where such images were not used, the CyberKnife ® system (Accuray Incorporated) was being used. A number of centers used motion reduction and/or compensation techniques: 9/24 used abdominal compression, eight used gating, four used the CyberKnife system and three used the Active Breathing Coordinator ™ (ABC, Elekta AB) system.
A total of 22/30 centers were described as academic; 24/30 as public; 28/30 as not for profi t and 25/30 as being part of a comprehensive cancer center. Most centers decided to start their program in the thorax, treating primary NSCLC (n ϭ 17) or lung metastases (n ϭ 9). The biggest challenges that had to be overcome were: knowledge (n ϭ 17); software (9); hardware (9); fi nancial (7); time/personnel (n ϭ 3); patient referrals (2); credentialing (2) and quality assurance/control program (n ϭ 1). Respondents identifi ed several area of additional support that they thought could have helped, including: interdisciplinary guidelines, multi-center collaboration, training, national/commissioner support and a national tariff.
At the time of the survey responding centers were offering SBRT for primary NSCLC (n ϭ 30), lung metastases (27), liver metastases (24), spine metastases (11), adrenal metastases (11), spine reirradiation (10), primary liver tumors (10), lymph node metastases (7), pancreas (4), prostate (4) and kidney (2). The majority indicated that there were voluntary national guidelines for SBRT and that they did not need to submit data to a national audit. In 16/30 centers all SBRT plans were peer-reviewed prior to treatment, and 29/30 centers reported that they tracked SBRT outcomes including toxicity with 24 reporting that they did so using a standard protocol outside of a study. In total 20/29 centers thought that SBRT should be limited to experienced/ high-volume centers and 29/29 thought that a minimum number of patients/year should be treated. The suggested number was 10 -100, with 21/23 between 10 and 50. The highest suggestions for minimum patient load were made in the England (100), Netherlands (50) and Germany (50).
Nine centers indicated that they required additional funds specifi cally to implement SBRT. Centers were reimbursed through various channels, sometimes more than one, including: regional schemes (n ϭ 13), insurance (n ϭ 13), national schemes (n ϭ 8), and the patient (n ϭ 6). Nonetheless 12 centers (in Germany, England and Austria) reported that they had experienced problems obtaining reimbursement. In 21/25 centers no additional personnel other than the treating technologist were required to be present at the time of treatment in order to receive the reimbursement; in four the physicist and/or radiation oncologist were also required to be present. Reimbursement covered planning and delivery, with 13/25 centers indicating that it also included at least a period of follow-up and 12 the consultation. In eight of 26 responses the reimbursement varied according to the number of fractions. In nine of 26 responses reimbursement specifi ed the defi nition of SBRT and two German centers mentioned that in-house/patient status was necessary to claim reimbursement. Estimated reimbursement amount (n ϭ 18) for lung SBRT was € 2750 -18 500, with 11/18 between € 5000 -10 000. The most variation in the amount reimbursed was reported within the England and Germany. Eight of 25 reported charging per lesion if they treated multiple targets while 9/15 replies indicated that lung SBRT reimbursement was less than conventionally fractionated IMRT/IGRT.

Discussion
We sent out a comprehensive questionnaire to obtain information about the practice of SBRT in selected European centers and achieved a respectable 67% response rate [3]. Based on this survey, in comparison with the number of new patients/year, the total number of lung and non-lung patients being treated with SBRT currently appears to be relatively modest. It is notable that the majority of centers started SBRT outside of a prospective study and that at least half the respondents felt that there was enough data to support the use of SBRT outside trials for multiple indications, despite the fact that existing evidence for SBRT is non-randomized. In the absence of what has been termed high-level evidence, more practical approaches to evaluating new treatment indications and technologies may be needed [5].
For the majority of centers, implementing SBRT posed challenges around knowledge acquisition, and nearly all would welcome specifi c educational programs, a number of which are now available. With this in mind, it was notable that only a minority of national radiation oncology training programs were required to provide formal SBRT experience. Specifi c consideration needs to be given as to how best to integrate advanced radiotherapy techniques into training curricula.
Encouragingly, there was considerable consensus in the practice of lung SBRT. Although the majority would treat without histology, nearly all required a prior FDG-PET/CT and many centers were also performing minimally invasive mediastinal staging [6,7]. Although there is ongoing debate over the role of central lung SBRT, most centers were already treating such tumors, illustrating how quickly clinical implementation happens, even for more controversial indications [8].
Although the majority thought that SBRT should be performed in experienced/high-volume centers, a recent study failed to demonstrate a learning curve for SBRT practice, or to fi nd evidence that either increasing SBRT experience or the implementation of new technologies led to improved outcomes [9]. It is important to note that variation in equipment, technology and technique has so far not been linked to outcomes like tumor control, which to date has been most closely attributed to the prescribed dose [10].
Although reimbursement varied substantially, there was some convergence to the € 5000 -10 000 bracket. A more complete assessment of the reasons behind this is merited. For example, we did not determine what proportion of the reimbursement was attributable to, e.g. staff overheads, building costs and investment in equipment.
Limitations to this study include the following. the sample was selective and limited in numbers and we acknowledge that there is selection bias. The number of for profi t and private sector centers was low and we recognize that the experiences reported in this survey may be different from those in other countries with different healthcare systems. The reader should also bear in mind that for various reasons it is possible that some of the data may not be exact (e.g. recall bias, estimated data, rounding). Indeed, this was specifically noted by at least one of the respondents. In addition respondents may not all have interpreted the questions in the same way. Such limitations are inherent to surveys like this and are one reason why we provided drop-down menus wherever possible. As expected, not all centers answered all questions. For example, some preferred not to comment on fi nancial matters. Nonetheless, despite these limitations the data summarized in this manuscript represent, to the best of our knowledge, the largest and most detailed survey of European SBRT centers to date.