MD DONALD B FULLER wrote:
>
> You wrote:
>
> >>I am wavering between RP and SI and have recently heard about a
> High =
> Dose Rate Temporary Brachytherapy treatment and am wanting additional
> =
> information about how it compares with Lower Dose Rate Permanent =
> treatments. Can someone enlighten me?>>
>
> >>Clinical State - T2a PSA 6.3 Gleasons 3-3 Small Prostate Small
> tumor near
> the bottom of the gland>>
>
> I'll take a stab at this one for you, though to do the comparison
> justice is beyond the scope of an e-mail note. We had a similar
> discussion on the "seedpods" thread a few months back.
>
> First of all, based on the profile you gave above, you appear to be
> an excellent candidate for permanent SI (contingent upon prostate <
> 50-60cc, no history of TURP surgery and reasonably normal lower
> urinary tract function). You would also appear to have a good
> probability of achieving long term disease free status with RP, XRT
> or XRT+ HDR brachytherapy.
>
> My own bias, fwiw, is that the presenting PSA, Gleason score and
> Tumor stage are more important to predicting the therapeutic outcome
> than the method used to treat the tumor. In fact, I am in an advanced
> stage of accomplishing a 400 patient study that attempts to support
> or refute this hypothesis (I've been working on this project since
> 1994).
>
> Now, lets do a brief comparison of the strengths of permanent SI vs.
> HDR Temporary Brachytherapy. All of this is simply my own opinion.
>
> Permanent SI:
>
> Permanent SI Strengths:
>
> (1) Precise method of radiation delivery (in experienced hands)
>
> (2) Radiation Dose: Permanent SI delivers a higher dose of radiation
> to the prostate than any other radiation treatment method. Nothing
> else even comes close. This high radiation dose is made possible by
> the rapid fall-off of radiation dose around the seeds, relatively
> sparing the surrounding structures to a higher degree than is posible
> with any other radiation delivery method.
>
> (3) Radiobiology: Permanent SI delivers the radiation much more
> slowly than HDR. The radiation therapy benefit to risk ratio is
> superior for low dose rate applications. In other words, all other
> factors being equal, a lower dose rate allows the safe delivery of a
> much higher total dose of radiation than a high dose rate.
>
> (4) Convenience: The patient enters and leaves the hospital (or
> "surgicenter") the same day.
>
> (5) Data: The 8 year (Seattle) data look very strong. In early stage
> patients, the disease-free survival result after 8 years of follow-up
> with ultrasound guided permanent SI appears as good or better than
> with any other method available (93% for a person of your
> description).
>
> (6) Side effects: These are usually just annoying and temporary after
> a permanent SI. Many of our permanent SI patients have resumed work
> within a day or two after the procedure (though they need to have
> good access to a rest room because of urinary frequency/urgency).
>
> Permanent SI Drawbacks:
>
> (1) The technique is not as easy as it looks. There is a possibility
> of seed migration even in experienced hands, leading to suboptimal
> coverage of the prostate by the high dose radiation cloud. If there
> is a suboptimal seed distribution, they may not be moved (or removed).
> This should be a relatively rare event if an experienced implanter
> is doing the procedure.
>
> (2) Side effects: Though permanent SI is often promoted as an "easy"
> method of treatment, it isn't always. A minority of patients (10-15%)
> have a prolonged severe course of symptoms after SI, including a
> swollen, inflamed prostate that closes off the urethra, requiring a
> catheter for days to weeks (rarely, months) to relieve. Once the
> seeds are in place, you have "bought the whole ride" - there is no
> way to interrupt the radiation delivery. Usually though, the side
> effects are quite managable with medications and pass after 3-12
> months.
>
> (3) The queue: The waiting time for seeds is becoming ridiculous, due
> to an obvious terrible underestimate of the demand for the procedure
> by the seed manufacturers, who now appear to be "caught with their
> manufacturing britches down" figuratively seaking.
>
> (4) The millstone around our necks: Permanent SI was tried about 30
> years ago and failed miserably. The technique then was terribly crude
> c/w the current technique but there is still an element of the
> medical community that hasn't forgotton that earlier SI experience.
>
> HDR Temporary Brachytherapy
>
> HDR Strengths:
>
> (1) Physics: An HDR case is accomplished by implanting about 14
> parallel plastic hollow catheters into the prostate through the
> perineum (skin between the scrotum and anus). The high intensity Ir-
> 192 source then "steps" through these plastic catheters (tubes) under
> computer control. The dose distribution of radiation is optimized by
> a computer software program after the implant.
>
> The physician may control/alter the "dwell times" at each stepping
> position, to alter the shape of the high dose radiation cloud that
> surrounds the tubes. In practical terms, this means that suboptimal
> tube placement may be "correctable" after the fact, through computer
> programming of the source stepping pattern. This optimization feature
> also allows the physician to differentially "heat up" one area of the
> prostate (e.g. the part that is thought to contain the majority of
> the cancer cells) and "cool off" a different part (e.g. the area
> around the urethra). This dose optimization feature represents a
> clear superiority of HDR over permanent SI. In permanent SI, the onus
> is on the physician to get the seeds in as close to perfect geometric
> position as possible, because once they're in position, that is where
> they stay forever.
>
> The HDR technique is more certain to cover the entire prostate in the
> high dose radiation cloud than permanant SI, due to the dose
> optimization feature. This may be more important for fellows with
> locally advanced cancers, where any little sliver of relative
> radiation underdosage may result in surviving cancer cells. I believe
> it to be a much less significant advantage in fellows with early to
> intermadiate stage cancers (most of them).
>
> (2) Side Effects: The radiation specific side effects of HDR are
> usually less long lasting than with permanent SI (but see below - In
> the short term, permanent SI is easier than HDR).
>
> (3) Scheduling: There is no wait for an Ir-192 source, like there is
> with the permanent isotopes.
>
> HDR Drawbacks:
>
> (1) Invasive: The plastic tubes may be very painful and remain in
> place for 24-48 hrs. The patient is essentially immobilized during
> this time period. Greater than or equal to 24 hrs flat on your back
> is no bargain, even if the procedural pain is reasonably well
> controlled.
>
> (2) The Hospital: You're in it longer with this technique. Personally,
> I prefer to be inside of hospitals as little as humanly possible.
>
> (3) Radiation Dose: The total radiation dose is lower with this
> technique, due to the radiobiology disadvantage of HDR. Some, if not
> all of the "physics advantage" of HDR relative to permanent SI is
> negated by this radiobiology induced HDR total dose "governor" IMO.
>
> (4) Radiobiology: The radiation therapy benefit to risk ratio is
> inferior with high dose rate applications c/w low dose rate. This
> means that all other factors being equal, there will be a higher risk
> of normal tissue damage with a higher radiation dose rate. This is
> the major reason that the total prescribed radiation dose is much
> lower with HDR techniques (A second reason for the lower total dose
> with HDR is that Ir-192 is a higher energy isotope, throwing the
> radiation dose further c/w the permanent isotopes, leading to more of
> a rectal injury concern).
>
> Because of the lower total radiation doses employed by the
> experienced practitioners of this technique and the physics/software
> advantage, serious HDR complications have been very rare. Nonetheless,
> the fundamental radiobiology disadvantage with HDR is indisputable.
> In summary, the practitioners of HDR are betting that superior
> radiation physics trumps inferior radiation biology.
>
> (5) Convenience: HDR is always combined with XRT. Its radiobiology
> limitations are too significant to allow it to be used as a stand
> alone treatment method. This means a total of 6-8 weeks of treatment
> appointments with HDR, c/w one day for permanent SI.
>
> (6) Data: The short term data appear encouraging with HDR but there
> are no long term data confirming the efficacy of HDR brachytherapy
> techniques. The technique is still too new.
>
> (7) Expense: HDR approaches are more expensive than permanent SI.
> This means a greater possibility of going to battle with your insurer
> to get the procedure covered (Incidentally, in San Diego, anything
> other than plain vanilla flavored XRT, including permanent SI, may
> generate a similar "insurance war").
>
> Well, there it is in a nutshell. There are probably other points that
> I did not do justice to by I think I caught the main ones. I'd be
> curious as to your reaction.
>
> Take care.
>
> Don