Re-irradiation of the prostate after first-line radiation therapy for “localized” prostate cancer


The use of second-line radiation therapy following biochemical progression after first-line radiation therapy for localized forms of prostate cancer has long been limited by concerns about tolerance for rectal and related radiation toxicities. Recent research has started to suggest that re-irradiation may now be becoming more viable through the use of a variety of methods designed to limit the risk for gastrointestinal and genitourinary toxicities associated with a second round radiation therapy.

As an example of just one of these types of methodology, has been reported by a Japanese team of clinical researchers.

In August this year, Kishi et al. published data on their re-irradiation of a single patient whose prostate cancer had recurred locally 18 months after first-line radiation with a standard (albeit low-dose) form of external beam radiation therapy. Re-irradiation of this patient was carried out by doing two things:

  • First, the patient was given a bolus injection of hyaluronate gel into the peri-rectal space to create and to maintain a small but significant distance between the prostate and the rectum and to decrease the size of the rectum during the re-irradiation process (thus lowering the risk for excessive radiation of the rectal wall during the re-irradiation process).
  • Second, the patient was re-irradiated using high-dose-rate (HDR) brachytherapy.

The authors report that:

  • The entire mprocedure was carried out in just 10 minutes, with no complications.
  • At > 3.5 years of follow-up
    • The patient’s nadir PSA level has been maintained at 0.03 ng/ml without androgen deprivation therapy.
    • There has been no other evidence of prostate cancer recurrence.
    • There has been no evidence of radiation-related toxicities higher than grade 2.

The authors conclude that “this technique is useful for achieving safe and curative re-irradiation of prostate cancer.”

The development of techniques like this that may allow safe and effective re-irradiation of the prostate opens the door not only to re-irradiation as a salvage technique after disease progression, but also to new “double dose” methods of radiation therapy for men with intermediate- and high-risk forms of localized prostate cancer (i.e., methodologies through which patients may get a first cycle of radiation therapy followed by a second, repeat cycle if the PSA level does not drop to an appropriate nadir level after the first cycle).

 

3 Responses

  1. Very interesting, and something that has been needed, since everything we have read in the past resisted re-irradiation. Unfortunately, there appear to be few locations in the U.S. with physicians having expertise in high-dose-rate (HDR) brachytherapy. Hopefully there will be more interest in the procedure as explained and such therapy becoming more available here in the U.S.

  2. Really interesting article.

    For low- to intermediate-risk, localized disease, this seems to indicate that you could radiate at a lower overall dose, or even employ a focused dose plan, for the primary treatment. This would minimize the chance of complications, at the (hopefully slight) risk of not “getting it all”. If there is a later sign of biochemical recurrence, you could be re-irradiated.

    Most oncologists advocate primary radiation at full strength, rather than the double dose method above. The approach is to “put all your chips on the table the first time”.

    This case indicates that other approaches may be possible, although obviously further study and clinical experience would be appropriate.

    Is anyone aware of this type of primary therapy being offered? I hope we can have further discussion and a follow-up article on this topic.

  3. Jim:

    I am aware of one patient with Gleason 3 + 4 = 7 disease in the UK who recently received initial low-dose radiation therapy. It didn’t work. He has been given repeat radiation with hormone therapy. Outcome not yet known.

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