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Comparative effectiveness of new treatments for early stage prostate cancer

Posted Dec 24 2009 12:00am

As initially reported in The Gray Sheet, an advisory committee to the US Food and Drug Administration (FDA) has suggested that new forms of device-based treatment for organ-confined prostate cancer should have to demonstrate effectiveness and safety in randomized clinical trials compared to active surveillance.

The theoretical logic of this suggestion is clear: any new treatment of localized prostate cancer should have to show that it delays progression by comparison to active surveillance in well-defined groups of patients, without an undue burden in terms of adverse effects. However, from a purely practical point of view, The “New” Prostate Cancer InfoLink wonders just how such guidance can be implemented fairly. For example, since there are already many forms of external beam radiation available and used to treat prostate cancer, is it actually going to be possible for the FDA to insist that modifications to the existing forms of radiation undergo clinical trials? And if so, how major must those modifications be to require randomized clinical trials? There is a whole new generation of proton beam radiation systems in development. Will those need to prove themselves? What about the next generation of laparoscopic “robots”?

Some surgeons have already been carrying out “focal” cryotherapy — in which only a part of the prostate is treated as opposed to all it. Is this really a “new” form of treatment, or just a modification of an already available therapy. By contrast, high-intensity focused ultrasound (HIFU) has not yet been approved for clinical use in the USA. Does this mean that the FDA could exercise the right to approve only whole gland treatment using HIFU (based on the current trials) but exclude approval of focal HIFU? That would seem a little bizarre to this observer if it is okay to carry out focal cryotherapy or focal brachytherapy!

The other issue is going to be whether it will be possible, in the USA, to randomize patients to trials of the type suggested. Some years ago the Southwest Oncology Group tried to implement a randomized clinical trial of surgery compared to external beam radiation therapy for localized disease. The trial would have required recruitment of 1,000 patients. It had to be abandoned after only 6 patients could be persuaded to participate.

Now it is true that in other countries there have been trials that successfully randomized patients for first-line treatment (e.g., the ProtecT trial in the UK). And a Canadian institution, earlier this year, reported the results of a trial in which patients were randomized to either external beam radiation or cryotherapy. However, The “New” Prostate Cancer InfoLink has serious doubts about how easy it will be to randomize patients to such trials in the USA.

Yesterday we posted a report on the development of the use of low-dose, alternating electric current (LDAEC) as a possible future treatment for early stage prostate cancer. If the advisory panel’s recommendation is followed, this form of treatment will have to be compared to active surveillance before the developers can market the equipment in the USA. This may or may not be a good idea. It will certainly drive up the cost of the equipment and the cost of treatment with such technology because the necessary Phase III clinical trials will cost millions of dollars to carry out. Sometimes, in our desire to develop the very best scientific evidence, we may place ourselves at risk of throwing out the baby with the bathwater. Potential financial backers of any company that wanted to bring LDAEC to market as a treatment for localized prostate cancer may now think more than twice about potential return on this investment!

Prostate Cancer International and The “New” Prostate Cancer InfoLink would like to believe that there will be a good deal more thought that goes into this recommendation before the FDA makes any sort of ruling. It has already been made evident that the FDA’s advisory panel was unable to come to any decisions about the collection of data on quality of life outcomes and complication rates related to the types of trial under discussion. That in itself should be a signal to the FDA that they are trying to knaw on a particularly tough bone.

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