This news release from a professional society of radiation oncologists summarizes a trial in 58 men with Stage 1 localized prostate cancer that found using a single treatment of high-dose-rate (HDR) brachytherapy (where radioactive implants are inserted directly into the tissue) may be an acceptable and safe alternative to typical longer, but lower doses of radiation.
Recognizing that a higher dose, single radiation treatment could be more toxic to tissues surrounding the prostate, this trial set out to measure the effectiveness and safety of such treatment. While the research was non-randomized, its generally positive tone was balanced by emphasizing that there needs to be additional follow-up research to see how it compares with conventional approaches.
After stating in the headline the treatment “may be safe and effective,” the release provides a fairly detailed description of harms.
A concern with this study is that nearly all of the patient volunteers would have been candidates for active surveillance–meaning that they did not need an active treatment. With no caveat that expert guidelines recommend surveillance for low-risk Stage 1 prostate cancers, this release engages in disease-mongering.
It is recognized that exposure to radioactive treatments can be harmful and so finding other ways to treat tumors in the prostate should be welcomed. If a treatment for localized prostate cancer which is administered in a single procedure, is equally effective and safe as conventional treatment, it is possible that patients may have fewer side effects and adverse events related to their prostate cancer treatment. This study provides some data on the safety and tolerability of the single dose of 19 Gy HDR brachytherapy compared to LDR brachytherapy, It is important to note that these patients were a very select sample of prostate cancer patients (low to intermediate risk) and so extrapolating those findings to other prostate cancer patients may not be appropriate.
There was zero mention of cost, which is unfortunate because presumably a single treatment would entail fewer costs than one that involved multiple procedures.
The main benefit focused on a vaguely described “biochemical progression,” which means that there was some evidence that prostate-specific antigen (PSA) levels increased. PSA is a protein produced by both cancerous and noncancerous tissue in the prostate. Determining PSA progression is more complicated following radiation because it takes time for the PSA level to stabilize (unlike following surgery to remove the prostate) before you can determine whether the PSA is rising. Biochemical progression is also a surrogate measure and does not imply that the cancer is–or will–clinically progress.
The researchers did acknowledge that the actual benefits are unknown, saying that “as the follow-up interval lengthens, 19 Gy dosing in a single fraction may or may not be sufficient to result in cure rates comparable to historical standards.”
The release provided detailed information on harms: “Within the six months following HDR therapy, seven patients (12.1%) experienced grade 2 urinary side effects, most commonly frequency/urgency (6.9%). No patients experienced short-term grade 3+ urinary toxicity or grade 2+ gastrointestinal (GI) toxicity. Rates were similarly modest for long-term side effects. Six patients (10.3%) experienced chronic grade 2 urinary toxicity and one patient (1.7%) experienced grade 3 chronic GI toxicity that subsequently resolved. No patients experienced long-term grade 3+ urinary toxicity or grade 4 GI toxicity.”
But given that many oncology experts would consider the treatment unnecessary, any level of toxicity could be considered unacceptable.
The lay reader would have benefited from a description of what “grade 2 or grad 3+” levels of toxicity means.
There were a few issues that could have been clarified: the fact that these men were quite low risk to start with, that five of the initial patients dropped out of the study (and we aren’t told why) and that this was a non-randomized, prospective clinical trial which is potentially subject to a series of biases.
The key takeaway is that this evidence does not establish the superiority of this approach to any other radiotherapy, any active treatment, or active surveillance.
The quote from a study author at the end of the release indicating that more research was required and this study was not definitive proof of the superiority of the 19 Gy fraction of HDR brachytherapy was a welcome caution, and somewhat at odds with the overall positive tone of the release.
Promoting brachytherapy radiation for treatment of low-risk men is a form of disease-mongering, particularly since there is no mention of the surveillance option. The American Urological Association (AUA) and National Comprehensive Cancer Network (NCCN) guidelines recommend that men with low-risk cancers be offered active surveillance.
The release doesn’t tell us who sponsored the study. The published report indicated there were no conflicts of interest.
The release says the study compared safety and effectiveness of single high-dose-rate (HDR) brachytherapy to longer courses of HDR treatment and that this alternative “may or may not be sufficient to result in cure rates comparable to historical standards.”
This sounds inconclusive. Just what are the “historical standards?” And why talk about “cure” rates?
A recently published randomized trial (PROTECT, Hamdy et al. NEJM, September 2016) of active monitoring, radiotherapy, and surgery for men with localized cancer found a 99% prostate-cancer specific survival for all treatment arms through 10 years of follow up. Speaking of a “cure” rate for low-risk disease that does not need to be cured is very misleading. H. Gilbert Welch, MD, MPH. professor of medicine at the Dartmouth Institute, has described these low risk diseases as “pseudo disease.”
The release doesn’t address availability but high dose brachytherapy has been available for years–and a Google search reveals many sites offering this treatment.
The news release suggests that this is a new strategy based on new research but that doesn’t appear to be the case.
According to UpToDate, an evidence-based list of practice recommendations published by Wolters Kluwer, use of single, high dose brachytherapy for prostate cancer is not novel: “The HDR brachytherapy dose is usually administered in one to four large dose fractions over a period of time, typically 24 to 40 hours. Patients receiving more than one fraction are usually admitted to the hospital (typically a 23 hour “outpatient stay”) for treatment when delivering multiple fractions and retain the perineal catheters in place for the entire period.”
The release detracts from the actual study when it states that the research “illustrates that a potentially curative dose of radiation…” This seems unjustified in the context of the trial. Is one ever really ‘cured’ from prostate cancer?
Giving caveats, yet dropping the line that “the single-treatment approach can eventually become a standard practice for prostate cancer treatment,” seems premature.
Urologist Willet Whitmore, MD, a founder of the urology oncology sub-specialty, spoke about localized prostate cancer cures this way: “If treatment for cure is necessary, is it possible? If possible, is it necessary?”