Comparative data on first-line radiation therapy — and the lack thereof
Posted Apr 17 2010 12:00am
The Agency for Healthcare Research and Quality (AHRQ) has released a draft version of a detailed techology assessment report entitled, “Comparative evaluation of radiation treatments for clinically localized prostate cancer: an update.” This draft report, by Ip et al. , “is distributed solely for the purpose of public and peer review and/or discussion at the MedCAC meeting” (scheduled for Tuesday, April 20, 2010).
The report catalogs with care the reasons why it is so difficult to provide a newly diagnosed prostate cancer patient with any definitive guidance on the relative merits of any one type of radiation therapy compared to any other and compared to either no treatment or deferred treatment.
The authors’ exclusive focus was on the various types of radiation therapy when used exclusively in the first-line treatment of clinically localized prostate cancer. The treatments included:
External beam radiation therapies (EBRT)
Combination radiation therapies, such as external beam radiation therapy with a brachytherapy boost.
In particular, the reviewers sought data comparing outsomes from treatment with these various types of radiation therapy to outcomes after no treatment at all, or no initial treatment (including watchful waiting and active surveillance), and alternate forms of radiation therapy. Outcomes of interest included overall and prostate cancer-specific survival, metastatic and/or clinical progression- free survival, freedom from biochemical (PSA) failure, quality of life, bowel and urinary toxicities, and sexual dysfunction.
The report asked three key questions:
The basic answers to these three questions were about as straightforward as you can get:
In fact, in only one situation did the review find that comparative evidence was sufficient to aid in decison making:
The report states that a “ ‘moderate’ level of evidence from eight studies suggests that higher dose EBRT is associated with increased rates of freedom from biochemical failure at 5 to 10 years compared to lower dose EBRT.”
The “New” Prostate Cancer InfoLink fully understands and appreciates the difficulties of conducting comparative trials of differing forms of interventional therapy like surgery, radiation therapy, cryotherapy, and high-intensity focused ultrasound (HIFU), as well as various types of patient monitoring (e.g., active surveillance). However, we also think the time has come to take this subject really seriously. We need to be able to tell patients not just what types of therapy are possible, but which types of therapy are most appropriate (based on their effectiveness and safety) for specific types of patient with localized prostate cancer.
It is also critically important to appreciate that we may not need to conduct randomized trials to come to these conclusions. It may be enough to carry out very carefully structured registry trials trials in which very precise data are collected from large numbers of patients treated according to highly-defined protocols at many centers over a period of time such that the outcomes of specific protocols in specific patient categories can be compared with accuracy.
Whatever it is we need to do to initiate the development of truly comparative data systems in order to define optimal practices, it is now long past time to begin to meet this need.