TECHNOLOGY AND THE PROSTATE
From the Advocate Health Care/Chicago Prostate Cancer Center Windy City Shootout
| INTENSITY-MODULATED RADIATION THERAPY —Juanita Crook, MD, Professor of Radiation Oncology, Faculty
of Medicine, University of Toronto, and Princess Margaret Hospital, Toronto
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| Intensity-modulated radiation therapy (IMRT): uses nonuniform radiation beamlets to tailor radiation dose to irregular
volume or target; computerized algorithm—controls multileaf collimator contained in linear accelerator; determines
dose intensity of beamlet; optimizes radiation dose throughout target volume; adjustable during treatment; collimator
leaves—remain static during 3-dimensional conformal radiation therapy (3DCRT); move independently during IMRT to
alter intensity of radiation
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| Ability of IMRT to accurately deliver known dose of radiation to target: requires—careful planning and preparation;
reproducibility of positioning, eg, to ensure accurate repositioning of body contours, place patient supine in custom Vac-
Lok cradle or prone using thermoplastic Aquaplast form; prostate movement—generally involves posteroinferior tilting;
usually caused by bowel peristalsis; minimal in 80% to 90% of patients (ie, <3 mm); can be monitored by use of gold
seed fiducial markers; in most cases, minor repositioning of patient and treatment couch can maintain accurate targeting
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| Ability of IMRT to reduce operator dependence
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 | Factors undermining brachytherapy: during “good” implantation, seeds can be displaced, creating isodosing; during
“bad” implantation, poorly placed seeds can miss almost one third of prostate volume; postplan assessment—uses
fusion of magnetic resonance imaging (MRI) and computed tomography (CT) to confirm accuracy of seed placement;
vagaries of contouring prostate on CT image undermine accuracy; problem area—small prostates treated with hormonal
therapy can be rubbery and mobile; needles inserted according to documented measurements can shift prostate
cephalad and fail to achieve proper depth of seed placement
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| Beam placement during IMRT: typically uses 7 noncoplanar beams; each beam enters prostate at unique angle and does
not meet with equal opposing beam entering from contralateral side of prostate; approach provides—security of target
coverage; well-defined margin around prostate; homogeneous delivery of radiation
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| Ability of IMRT to manage any size prostate: pubic bone does not hinder IMRT; with brachytherapy—once prostate
volume >50 mL (depending on patient’s skeletal frame), pubic arch can prevent insertion of needles and radioactive
seeds into anterior shoulders of prostate located behind pubic bone
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| Ability of IMRT to adapt to wide variety of clinical scenarios: favorable-risk disease—well-performed brachytherapy
good option for administering high doses of radiation; IMRT viable alternative for managing patient with large prostate
or poor pretreatment urinary function
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| IMRT for intermediate- and high-risk disease: provides certain advantages over combination of external beam radiotherapy
(XRT) and brachytherapy; in men with high-risk disease, IMRT—delivers rapid dose gradients next to target;
avoids irradiating entire bladder wall when treating portion of median lobe that protrudes upward into middle of bladder;
provides concave distribution of radiation that can reach seminal vesicles that droop down around rectum; carries
“wings” up to irradiate obturator lymph nodes and nodes located higher in pelvis; when used to manage pelvic lymph
nodes, effectively treats nodal packets while sparing bladder and small bowel; bottom line—IMRT essentially uses
one treatment plan for prostate, seminal vesicles, lower pelvic nodes, and nodes located higher up in pelvis
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| Ability of IMRT to provide safe dosing: important consideration; safe dose escalation with IMRT produces definitive
benefit for biochemical relapse-free survival
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| IMRT and acute and long-term patient tolerance: survey of rectal toxicity data show that IMRT can—achieve cutoff
threshold for reducing rectal toxicity, ie, exposing ≤25% to 30% of rectum to <70-Gy dose of radiation; provide tissue-
sparing up to and including high-dose ranges of radiation
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| Brachytherapy: associated with higher rate of urinary toxicity than IMRT, eg, patients experience marked increase in rate
of transurethral resection of prostate (TURP); rate of gastrointestinal (GI) toxicity after brachytherapy—potential
problems include changes in bowel habits, tenesmus, rectal bleeding, ulcers, fistulas, fecal incontinence, and necrosis
requiring surgical correction; combination of brachytherapy boost following XRT increases nature, severity, frequency,
and duration of complications
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| When used to treat prostate cancer, IMRT: safely delivers high doses of radiation; associated with low catheterization
rates; can be used in men with larger prostates and poor voiding function before IMRT; mandates paying close attention
to dose-volume constraints; with careful planning, can keep risk for proctitis grade II or higher to ≈5%; rarely produces
rectourethral fistulas; requires careful monitoring of prostate position; permits effective expansion of isodoses to achieve
proper disease margins; when necessary, can achieve selective dose increases in specific areas requiring treatment
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| BRACHYTHERAPY —Steven Kurtzman, MD, Attending Physician and Partner, Western Radiation Oncology, Inc.,
Mountain View, CA
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| Brachytherapy: achieved new degree of clinical efficacy after introduction of transrectal ultrasonographic guidance; current
popularity driven by patient demand
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| Real-time implantation with computerized dosimetry and intraoperative planning: facilitates delivery of appropriate radiation
dose to prostate while protecting urethra and rectum; expands number of patients who can undergo brachytherapy;
can be performed on almost any size prostate as long as pelvis accommodates approach; allows surgeon to move
patient intraoperatively and reconfigure device to account for movement; can be performed on men who have undergone
TURP, or salvage with XRT or brachytherapy
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| Brachytherapy: permits conformal dose distribution to prostate; most beneficial in men with high-risk disease; convenient
for patient and physician; can salvage men who failed previous radiation therapy (eg, seeds have been reimplanted in men
who have failed previous brachytherapy); fosters productive relationship between urologist and radiation oncologist; easier
to master than IMRT; invasive procedure requiring surgical facilities and anesthesia; associated with increased severity
of urinary side effects; requires skilled operator
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| IMRT: noninvasive; produces less short-term urinary morbidity, ie, side effects less severe acutely; patient selection less
critical, ie, patients not stratified as much by risk factors; inconvenient, ie, therapy administered daily from Monday to
Friday for ≥8 wk with dose escalation; prostate motion complicates targeting; requires larger trained staff
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| Brachytherapy technique: performed in one procedure (skill and good preoperative planning achieve consistent results);
intraoperative planning—achieves elegant dose distributions; eliminates concerns over patient set-up and movement
of patient and prostate; dosimetry corresponds with—biochemical and local control; complication rates
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| Real-time procedure: equipment—ultrasonography (US); intraoperative treatment planning computer; technique—
visualize gland (brachytherapy facilitates effort to visualize glandular target, urethra, and rectum); contour entire prostate
at 5-mm intervals; use data to produce 3D reconstruction of gland and develop idealized plan for needle and seed
placement; use imaging to monitor needle placement in relation to rectum; recapture gland images to account for
movement or changes in shape of gland; use editing tools to change shape and position of prostate on each imaging cut;
modify technique based on changes occurring in rectal area; line up needles in real time; using sagittal imaging, advance
needle tip to base of gland; drop seeds sequentially along tract; real-time monitoring—controls seed placement
and spacing from rectum; enables surgeon to “sculpt” dose
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| Intensity-modulated radiation therapy: prostate movement requires patient be immobilized and prostate localized (no
consensus exists as to how this should be achieved); forces physician to make one plan work for many prostate positions;
dose escalation requires minimal margins; localization—key concern; poor US creates problems; fiducial markers probably
more reliable means of verifying prostate position (approach more user-dependent); rectal balloon—viable option
for minimizing prostate volume; requires performing more invasive procedure on daily basis
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| Data survey: brachytherapy—direct relationship between radiation dose administered and local and biochemical control;
mature data reveals brachytherapy achieves excellent outcomes across all risk groups; IMRT—factors limiting assessment
of treatment efficacy include relative lack of available data, shorter follow-up times, and failure to determine optimum
radiation dose
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| Complications: brachytherapy—good dosimetry reduces risk for erectile dysfunction and urinary and GI complications;
caveats—potential for developing impotence remains concern for ≈3 yr postbrachytherapy; limiting prostate volume receiving
100% of prescribed dose of radiation (V100) to <1.3 mL limits risk for grade II rectal bleeding to <5%; IMRT—
well tolerated; associated with slightly greater impotence risk
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| Ease of treatment: brachytherapy—easier to perform than IMRT; essentially outpatient procedure; patients require minimal
preparation (ie, enema at night and in morning); painless (ie, patients can be discharged without pain medication);
patients can return to activity next day; places less demand on physician time; cost-effective (ie, approach does not require
large staff; equipment requires relatively minimal capital investment); IMRT—patient requires ≥2 mo of daily
therapy; relatively invasive (ie, use of fiducial markers to monitor patient and rectal balloon to immobilize prostate);
places increased demand on physician and staff for set-up, verification, and treatment; expensive
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| Developments in brachytherapy: advances in targeted therapy include—technical feasibility of intraoperative planning
that permits adjusting dose gradient to cover areas of increased risk; potential role of MRI and prostascint scanning;
capability to contour and shape appropriate radiation dosing within gland; 131 C—new isotope; has energy level comparable
to that provided by 125 I but with half-life of 9.7 days; administers full dose of 100 Gy; expected to equal therapeutic
efficacy of other isotopes with shorter duration of side effects
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| LAPAROSCOPIC RADICAL PROSTATECTOMY —Timothy G. Wilson, MD, Director, Department of Urology/Oncology;
Director, Prostate Cancer Program, City of Hope Cancer Center, Duarte, CA
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| Introduction: open radical prostatectomy has proven efficacy; laparoscopic radical prostatectomy (LRP) can—reduce
blood loss and pain; improve recovery of potency and continence; robotic prostatectomy data—marked improvement
in positive margin rates suggestive of learning curve; 7% positive margin rate for T2 disease compares favorably with
positive margin rates achieved with open prostatectomy
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| Data comparing straight LRP vs da Vinci robotic prostatectomy show: robotic surgery and LRP had similar positive
margin rates; operative times for robotic approach have decreased; blood loss routinely low; patients undergoing straight
LRP had higher complication rates (finding reflects learning curve); after LRP, patients had—greater reduction in creatinine;
transfusion rate ≈2%; slightly more significant problem with ileus; after robotic surgery, patients—required
shorter duration of hospitalization and less catheter time; had median time to continence of 44 days, ie, no pads or 1 pad
for security; additional observations—bladder neck contraction rare in both treatment groups; men undergoing LRP or
robotic procedure achieved similar time-to-potency rates
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| LRP (straight or robotic) vs open radical prostatectomy: reduction in blood loss main reason why men undergoing LRP
recover more quickly and less likely to be anemic; American Urological Association/Lahey Clinic data comparing
outcomes among obese men who underwent radical retropubic prostatectomy (RRP) or LRP—patients undergoing
straight LRP required shorter operating time, had less blood loss, required less narcotic, and had shorter duration of hospitalization;
positive margin and complication rates similar between treatment groups; Vanderbilt University School of
Medicine data—when compared to open prostatectomy, men undergoing robotic prostatectomy had less blood loss and
greater improvement in postoperative hematocrit; Mayo Clinic data comparing patients undergoing RRP to robotic
prostatectomy showed—both techniques achieved similar margin rates; robotic surgery produced slightly higher complication
rates and lower transfusion rates; Henry Ford data showed, with sufficient experience, robotic surgery—
reduces blood loss; improves transfusion and complication rates and postoperative hemoglobin and hematocrit levels; reduces
duration of hospitalization and catheterization; reduces time to continence, erection, and intercourse; improves
positive margin rate
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| When compared to open radical prostatectomy, as experience with LPR and robotic prostatectomy increases: operative
times will improve; blood loss will decrease routinely among men undergoing LRP (whether performed with standard
or robot technique); duration of hospital stay and catheterization will be slightly less for robotic prostatectomy;
overall complication rates will not be significantly different between LRP and robotic surgery; time required for men to
recover continence will continue to improve; better visualization of nerves and 3D imaging will reduce rate of sexual
dysfunction; clinical experience shows—techniques achieve identical oncologic control; robotic surgery less tiring for
surgeon and more ergonomic
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Educational Objectives
| The goal of this program is to educate the listener about current technology for managing prostate cancer. After hearing and
assimilating this program, the clinician will be better able to:
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| 1. Assess the clinical merits of intensity-modulated radiation therapy (IMRT)
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| 2. Review techniques developed to improve patient tolerance of IMRT.
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| 3. Compare the therapeutic efficacy and safety of brachytherapy to IMRT.
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| 4. Evaluate study data comparing laparoscopic radical prostatectomy (LRP) to open radical prostatectomy.
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| 5. Determine the technical and therapeutic benefits derived from using the da Vinci robot to perform prostatectomy.
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Discussed on This Program
Sildenafil citrate [Revatio, Viagra]
Suggested Reading
Ahmad S, Vlachaki MT: Impact of margin on tumour and normal tissue dosimetry in prostate cancer patients treated with
IMRT using an endorectal balloon for prostate immobilization. Australas Phys Eng Sci Med 28:209, 2005; Buyyounouski
MK et al: The radiation doses to erectile tissues defined with magnetic resonance imaging after intensity-modulated radiation
therapy or iodine-125 brachytherapy. Int J Radiat Oncol Biol Phys 59:1383, 2004; Hu JC et al: Perioperative complications
of laparoscopic and robotic assisted laparoscopic radical prostatectomy. J Urol 175:541, 2006; Jani AB et al:
Intensity-modulated versus conventional pelvic radiotherapy for prostate cancer: analysis of acute toxicity. Urology
67:147, 2006; Joseph JV et al: Robot-assisted vs pure laparoscopic radical prostatectomy: are there any differences? BJU
Int 96:39, 2005; Merrick GS et al: The importance of radiation doses to the penile bulb vs crura in the development of
postbrachytherapy erectile dysfunction. Int J Radiat Oncol Biol Phys 54:1055, 2002; Stone NN et al: Comparison of intraoperative
dosimetric implant representation with postimplant dosimetry in patients receiving prostate brachytherapy.
Brachytherapy 2:17, 2003.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial
relationship with the manufacturer or provider of any commercial product or service discussed. The following has been disclosed:
Dr. Kurtzman is affiliated with C. R. Bard Inc.
Drs. Crook, Kurtzman, and Wilson gave their scientific presentations at the Advocate Health Care and Chicago Prostate
Cancer Center Windy City Shootout, held June 24 to 25, 2005, in Chicago, IL. The Audio-Digest Foundation thanks the
speakers and the sponsors for their cooperation in the production of this program.
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