DOS 711 - Weeks 6 & 7 Discussion
Writing Prompt
Initial Post: Popular and Scholarly Articles on SBRT for Prostate Cancer
Part 1: Trade Magazine
Published information sources can be loosely categorized as either scholarly or popular in nature.1 Popular sources are intended for a broad audience (populace) and are typically written by non-experts who may write about a completely unrelated topic in their next publication. Popular sources can take the form of opinions, descriptions of events, commentary, or even summaries of scholarly sources. Trade magazines are a form of popular source that are written with a topic-specific audience in mind. The audience may be a self-selecting group of the general public who have an interest in a particular cross section of industry, or the audience may be limited by formal affiliation with professional organizations. In either case, trade magazines will tend to narrow the focus of the content while still keeping the content relevant to a broad spectrum of stakeholders such as clinicians, researchers, administrators, educators, and general staff within that industry.
Articles written for popular sources use general language that is understandable by people who are not subject experts.2 The authors may be paid, either as staff writers, freelance journalists, or invited authors who receive honoraria. The tone may be intended to influence opinion, highlight differences of opinion among others, or simply report facts, all at the author's discretion. There may be commercial or financial interest in the form of sponsorship to highlight a product or service, and authors are not compelled to list the sources of their information.
An example of an article from a trade magazine is an article by freelance medical writer Beth W Orenstein entitled "SBRT for Prostate Cancer", which was published in Radiology Today Magazine in July, 2011. The article takes the form of a point/counterponit summary of current efforts to use Accuray's CyberKnife to perform stereotactic body radiotherapy (SBRT) procedures to treat prostate cancer. Orenstein solicited opinions from several experts in the field to discuss this topic, including Dr. Alan Katz, a radiation oncologist who had been treating prostate cancer with CyberKnife for 4 years at the time of writing; Dr. Gerald Chodak, a former urologist turned medical writer who is a subject matter expert on prostate issues; Dr. Dwight Heron, the chairman of the radiation oncology at University of Pittsburgh Medical Center Shadyside, an early adopter of CyberKnife; and Rohit Inamdar, a senior medical physicist and senior associate in the Applied Solutions Group at the Emergency Care Research Institute, which researches approaches for improving patient care. Most of the article is focused on the experience and success that Katz has had with CyberKnife, and it offers a strong endorsement of the utility of the technology. However, many of the claims made by Katz are countered by quotes from the other experts, who offer words of skepticism, clarification, or even caution.
I found the article to be a very useful introduction to a topic that was new to me. I had not been aware that current research suggests that the radiobiology of prostate cancer can favor hypofractionation schemes that deliver high doses in fewer fractions than conventionally fractionated therapy and with lower total doses. I asked one of the prostate specialists at my clinical site, Dr. Abhishek Solanki, who confirmed this finding (oral communication, March 24, 2015) and recommended several additional research sources on the topic, one of which is highlighted in Part 2.
The article highlights promising results from 4 to 5 years (at the time of publication) of followup on patients who have undergone SBRT prostate treatment. Katz reported that the CyberKnife SBRT treatment showed equivalent or even better outcomes than traditional treatments based on followup prostate-specific antigen (PSA) blood test results, survival rates, recurrence rates, and the frequency of occurence of common side effects such as urinary, bowel, and sexual problems. The short treatment cycle of only 5 treatment visits versus as many as 44 under conventional fractionation schemes was also highlighted as an advantage of the SBRT approach.
The chief criticisms directed at the recommendation to use CyberKnife SBRT for prostate cancer treatment revolve around two factors: whether 4 years of data is enough, and whether finances rather than patient outcomes are driving the recommendation. I was pleased to see these counterpoints included in the article because it made me stop to think about the quality of the claims that were being made. Katz suggested that 4 years of PSA data is enough to have predictive power for longer term results, based on long term findings made during research into the efficacy of prostate seed implants. Chodak cautioned that prostate cancer is slow growing, and 4 years may not be enough time for problems to develop. Furthermore, Chodak pointed out that in other prostate-related studies, such as a study that tested hormone therapy combined with radiation, the short term data suggested a different finding than what was revealed in longer term followup. Chodak was not trying to say that SBRT can not live up to its claims, but rather was cautioning against jumping to that conclusion prematurely.
The financial criticism Inamdar suggests that a push to treat prostate cases on CyberKnife before adequate data supports it may be driven not by evidence-based best practices, but by a desire to fill up treatment schedule slots to keep the machine busy, which helps to pay back the high cost of the machine. Katz counters this claim by highlighting that a course of CyberKnife prostate treatment only costs about 80% of what IMRT costs. I found this argument troublesome, because the short fractionation scheme means that treatments only take one ninth as long as traditional treatments. Considering that CyberKnife time slots (45 minutes) are longer than IMRT time slots (15 minutes) (Teresa Kent, oral communication, March 24, 2015), one can charitably propose that 3 times as many patients can be treated on a CyberKnife machine than on a linac. Even at 80% of the cost of IMRT, this would still translate to 240% of the income opportunity if a center pushed CyberKnife aggressively. The counter-counterargument to this is that processing 3 times as many patients means 3 times as much planning activity which must be adequately staffed, so the debate can continue Ad Nauseum.
Overall, I was pleased by the analysis offered in the article, and I find myself curious to learn more about this topic. In this respect, this popular source was successful in presenting a new topic to an audience member who was not yet an expert in the subject matter and keeping them interested.
Grayden, Chicago
- Identifying types of information and why information types matter. Loyola University Chicago Website. http://libguides.luc.edu/gettingstarted/infotypes. Updated March 24, 2015. Accessed March 24, 2015.
- Lenards N, Weege M. Readings and Writing in RT and Med Dos. [Powerpoint]. La Crosse, WI: UWLAX Medical Dosimetry Program; June 29, 2010.
- Orenstein BW. SBRT for prostate cancer. Radiology Today Magazine Website. http://www.radiologytoday.net/archive/rt0711p24.shtml. Published July, 2011. Accessed March 24, 2015.
Part 2: Peer Reviewed Professional Journal
In contrast to popular sources such as trade magazines, scholarly sources of information such as peer-reviewed journals are written by experts for experts.1 These publications are written in a formal style that uses a standardized structure to organize the content. The content usually reports the results of original research in a narrowly focused topic area. The scientific process of pursuing new knowledge involves forming a hypothesis, designing a methodology to test that hypothesis, gathering data, analyzing it, and then forming conclusions based on the data. This process is reflected in the formalized structure of the document. Since the target audience consists of readers who are presumed to be familiar with the topic area, the language in the document may use specialized terminology that would be unfamiliar to a general audience. Since the content and audience are usually academic in nature, the grammar and writing style is not bound by simplicity requirements designed for general audiences.
The most distinctive feature of scholarly writing is the evidence of the collaborative nature of academic research. All ideas and data presented in the document that are not the author's original work are annotated with their source, so as to give credit to their originators. Depending on the formal style in use, this can take several forms. In the American Medical Association (AMA) style of writing, externally-sourced ideas and data are marked with superscripted numerals,2 and a corresponding numbered list at the end of the document contains the information about the source of that information.
Another less visible form of collaboration distinctive of scholarly sources is the peer review process for publication. Peer reviewed publications do not simply accept articles and publish them. Submissions are first passed to a review panel composed of experts in the field, who review the submission for quality of writing and of research. The panel verifies that the ideas presented are indeed original, and that the research methodology used to test the hypothesis is sound. After this, the panel reviews the data and analysis to decide whether the conclusions are adequately supported or not. The peer review panel may return the submission to the author with suggestions for additional work and refinement instead of publishing it. Submissions are only published if they satisfy the peer review test of quality. Because of this, scholarly sources are generally more trustworthy than popular sources, which don't have similar quality control measures in place.
An example of a peer-reviewed journal article is "Stereotactic body radiotherapy for localized prostate cancer: Pooled analysis from a multi-institutional consortium of prospective phase II trials", which was published in November, 2013 in the journal Radiotherapy and Oncology. This article had 11 collaborating authors representing 8 institutions: Christopher King, Debra Freeman, Irving Kaplan, Donald Fuller, Giampaolo Bolzicco, Sean Collins, Robert Meier, Jason Wang, Patrick Kupelian, Michael Steinberg, and Alan Katz, who was extensively quoted in the article from Part 1.
This article is what the article from Part 1 wanted to be. Instead of retrospectively reporting the results of a study of 41 patients from two institutions over 5 years,3 it aggregates the post-SBRT data from 1100 patients enrolled in prospective phase 2 clinical trials over 8 years from 8 institutions.4 Various subpopulations of the 1100 patients had been used in prior publications, and the article lists 17 prior publications that attempted to evaluate the efficacy of hypofractionation. Of these, 9 were studies of moderately accelerated fractionation schedules, and 8 were studies of 5 fraction SBRT schedules. A much older study from the 1980s was also highlighted as being the first long term study to investigate hypofractionation for prostate treatment, but that study used much older planning techniques that predated CT based planning. The literature review also pointed to a study of over 14000 patients with various fractionation schedules that attempted to determine the alpha/beta ratio for prostate cancer and found it to be extremely low, in the range of 1.0 to 1.7, supporting the hypothesis that it responds best to the heavy hit of high doses per fraction.5
With this setup, the article states that its purpose is to evaluate the effecitveness of SBRT for localized prostate cancer.4 It does not explicitly state that it will do so in a more comprehensive way than has previously been possible, but this seems to be implied. The methodology section of the article states tha the data from the prior SBRT studies was aggregated, and almost as much unpublished data was added.
The pool of eligible patients for this study included those who had biopsy proven, newly diagnosed, nonmetastatic, untreated prostate cancer. Subjects were evaluated and grouped based on PSA scores and Gleason scores using a standardized methodology into low, medium, and high risk pools. All of the patients received 5 fraction SBRT totalling between 35 and 40 Gy. Their treatment plans were optimized in standard ways, and they received followup evaluations at regular intervals after their treatments. Androgen deprivation therapy (ADT) was allowed at each physicians discretion and this data was tracked as well to help evaluate whether ADT has any effect on the final results.
The findings of this study echoed Katz's assertions from his small study from the article in Part 1. The biochemical relapse free survival (bRFS) rate based on PSA scoring was 93% for the entire population, and 95%, 84%, and 81% for low, intermediate, and high risk patients respectively. The study found no correlation between ADT and bRFS rates in any subpopulation. The incidence of GU and GI toxicities was not evaluated in this aggregated study because of confounding factors such as variations in treatment techniques between the sources of the data, however, the literature review quoted previously published complication rates of 1-3% from the previous smaller SBRT studies. One study that gave SBRT dose totalling 50 Gy reported a 7% grade 3 toxicity rate for both GI and GU systems. Because of this, the authors determined that SBRT doses beyond 40 Gy were not warranted.
While this study still doesn't span 10 or more years of followup, it does include a larger patient population than any previous study of the topic. The authors conclude that PSA relapse-free survival rates for SBRT treatment of prostate cancer compare favorably to other treatments, and SBRT should be considered as an option for treatment of low and intermediate risk patients with localized disease.
This research is promising. The large pool of data supports the 5 year data effectively, but there is still an unanswered question of whether 5 year data will accurately predict the results of 10 or more years of followup of these patients. Unfortunately, the only way to answer that is to wait a few more years and continue to follow these patients. In the mean time, any physicians and patients who opt for SBRT treatment for prostate cancer should be encouraged to enroll in clinical trials so that this body of knowledge can continue to grow.
Grayden, Chicago
- Identifying types of information and why information types matter. Loyola University Chicago Website. http://libguides.luc.edu/gettingstarted/infotypes. Updated March 24, 2015. Access March 24, 2015.
- Iverson C, Christiansen S, Flanagin A, et al. AMA Manual of Style: A Guide for Authors and Editors. 10th ed. New York, NY: Oxford University Press; 2007.
- Orenstein BW. SBRT for prostate cancer. Radiology Today Magazine Website. http://www.radiologytoday.net/archive/rt0711p24.shtml. Published July, 2011. Accessed March 24, 2015.
- King CR, Freeman D, Kaplan I, et al. Stereotactic body radiotherapy for localized prostate cancer: pooled analysis from a multi-institutional consortium of prospective phase II trials. Radiother Oncol. 2013;109(2):217-21. http://dx.doi.org/10.1016/j.radonc.2013.08.030
- Dasu A, Toma-Dasu I. Prostate alpha/beta revisited - an analysis of clinical results from 14,168 patients. Acta Oncol 2012;51:963–74.
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Academic Courses > DOS 711 > Popular and Scholarly Articles on SBRT for Prostate Cancer
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Written March 25, 2015
Second Semester, 3 Months into Internship |