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Hospital release makes unjustified leap from low toxicity found in safety trial to pronounce a “cure”

UT Southwestern research shows 98 percent cure rate for prostate cancer using SBRT

Our Review Summary

prostate cancerThis news release draws from a Phasel/ll safety study of 91 patients who were given a concentrated form of higher-dose radiation known as stereotactic body radiation therapy, or SBRT, instead of typical radiation therapy for early-stage prostate cancer. The study was designed to test the toxicity of increasing levels of radiation, not to assess the survival rate.  While the five-year study showed benefits, the release failed to provide the numbers and details that we believe would help readers understand the risks vs. benefits. The “cure” rate referred just to men who had no evidence of rising prostate-specific antigen (PSA) — and the study acknowledges that most men were not actually followed for 5 years so a “cure rate” was statistically estimated. However, over a third of the men had low-risk cancer where the 5-year cancer-specific survival is estimated to be 100 percent. It’s not certain that these men actually required treatment.


Why This Matters

The National Cancer Institute estimates there will be about 180,890 new cases of prostate cancer diagnosed in the United States this year. Some of them will be treated with active surveillance, the “watch and wait” treatment. More aggressive cancers may require surgery, radiation or chemotherapy. Among those treated with radiation, stereotactic radiotherapy (SBRT), an alternative form of radiation therapy described in this release, may offer a shorter course of treatment (five sessions) compared to external beam radiation therapy which is typically delivered over the course of about six weeks. The shorter SBRT approach suggests an important convenience benefit to patients. Treatment toxicity with this procedure was also low, according to the release, although there was no control group in the study to compare it with.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The release does not discuss costs. We find this disappointing, but also ironic. In a very quick search, we discovered that one of the major topics regarding SBRT is its low-cost relative to the existing therapies. In the Journal of Oncology Practice, authors in 2012 directly compared it cost-wise to another method and concluded: “SBRT for low- to intermediate-risk prostate cancer has great potential cost savings for our health care system payers and may improve access to radiation, increase patient convenience, and boost quality of life for patients.”

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

This is an odd news release. The study, described as a Phasel/ll, was conducted to assess the safety of escalating doses of radiation with the goal of determining whether varying doses of SBRT had an acceptably low rate of toxicities. The study was not intended to provide any definitive assessment of survival benefit, and yet that’s what the release is about.  It states:

“The study — the first trial to publish five-year results from SBRT treatment for prostate cancer — found a 98.6 percent cure rate with SBRT, a noninvasive form of radiation treatment that involves high-dose radiation beams entering the body through various angles and intersecting at the desired target.”

The “cure” rate referred just to men who had no evidence of rising PSA — and the study acknowledges that most men were not actually followed for 5 years so “cure rate” was statistically estimated.  However, over a third of the men had low-risk cancer where the 5-year cancer-specific survival is estimated to be 100 percent. It’s not certain that these men actually required treatment.

Beyond that, the release did not quantify benefits precisely. There was only one sentence directly addressing the study results. There was no description precise study group demographics. The release does not define “cure” as it is used in the sentence below and the headline.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The release does include a paragraph about urinary side effects (among others) for patients in the trial. But the release deliberately seems to try to minimize these. (Editor added italics.)

“In addition to shorter treatment times, researchers found that side effects were not necessarily different compared to other forms of prostate cancer treatment. In the short term, the side effects of SBRT can include urinary issues (urgency, frequency and burning) and rectal irritation, which are often temporary and reverse within four weeks of treatment. Researchers found a small risk of longer-term urinary and rectal complications, which is also comparable to conventional treatments. Decrease in erectile function was seen in 25 percent of patients, fewer than with conventional radiation or surgery, said Dr. Hannan.”

Many men might find a one-in-four chance of impotence a high price to pay for treatment for early-stage prostate disease. We have to complain that the release does not give us numbers for the harms — in any way that is meaningful and allows us to compare this new therapy to existing therapies.

The phrase “not necessarily different” is not helpful. The phrase “a small risk” is not giving us a number we can use.

As noted above, a substantial proportion of the patients might not have needed treatment — so that even a “small risk” of complications would be unacceptable. In the absence of a comparison group, no conclusions can be drawn as to whether this represents a less harmful active treatment option.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

This was basically an observational cohort study which was powered to accurately determine the proportion of men who would suffer radiation toxicity. The study was not designed to determine whether this treatment was more effective than other radiation modalities or surgery. We did not find the sort of descriptions of the study protocols that we expect from a release. The study — which we took the time to read — appears of good quality but the release did not tell us that. The study was limited to 91 patients, which isn’t a very big study.

Does the news release commit disease-mongering?


There is no disease mongering.

Does the news release identify funding sources & disclose conflicts of interest?


The release provides the funding source (the U.S. Department of Defense) although it does not explicitly comment on the absence of conflict.

Does the news release compare the new approach with existing alternatives?


The release gives us some information about this treatment vs. traditional radiation and lists other important alternatives including prostatectomy (surgical removal of the prostate gland), brachytherapy (the implantation of small radioactive seeds), and external beam radiation. One alternative not mentioned — which is appropriate for low-risk cancers — is active surveillance (monitoring the patient and deferring active treatment).

Does the news release establish the availability of the treatment/test/product/procedure?

Not Satisfactory

The news release hints that SBRT is available at the study location but does not provide readers with any other indication about its availability in other regions. We do know that SBRT is widely available at other academic medical centers and has been in use for more than a decade. It is also sometimes marketed as the “CyberKnife” at private medical facilities.

Does the news release establish the true novelty of the approach?


The release claims that the study was the first published trial to follow patients receiving SBRT for five years.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Not Satisfactory

We question the use of “cure” in the headline. And, while the current report did focus on “freedom from biochemical failure (i.e., no increase in PSA)” — which is not the same as cure — the primary intention of the study was to assess toxicity.  Talking about a “strikingly” high cure rate is misleading given the absence of a control group.

Total Score: 4 of 10 Satisfactory


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