Published on March 4, 2013
Radiation Therapy for Prostate Cancer Robert Miller MD www.aboutcancer.com
Prostate Guidelines1. Low risk of extracapsular spread, then external beam or seeds alone2. Intermediate risk then some (or all) of the radiation should be by external3. High risk then hormone therapy should be added to the radiation4. External beam should be daily image guided intensity modulated (IGRT)5. Need high dose radiation (75 to 81 Gy)
The prostategland has acapsule aroundit, and cancersarise close tothe capsule, thecancer mayinvade throughthe capsule
Age: 67 / Stage T1c / Gleason 6 / PSA 5 =27.6% risk of extracapsular spreadAge: 67, Stage T2b, Gleason 7/ PSA 12 =86.2% risk of extracapsular spread
Laparoscopic Prostate Surgery The surgeon tries to dissect the prostate away from the rectum, bladder, the neurovascular bundle (nerves) and penile urethra
Radiation Fields with Prostate CancerA Low Dose Large Area (Phase 1) With radiation it is possible to include a wider area around the prostate to cover any cells that may have escaped After the highest safe dose is reached, the radiation target will be made smaller
Radiation Fields with Prostate CancerA High Dose Large Area (Phase 2) The final, high dose radiation target will be focused very precisely only on the prostate gland
Prostate Cures Rates by Treatment and Dose External beam > 72Gy Surgery or Seeds External beam < 72Gy IJROBP 2004; 58:25 Months
Prostate Cancer Relapse Rate by Radiation Dose < 72Gy 72 - 82Gy 82Gy Years Kupelian. IJROBP 2008:71:16
Salvage (postOp) radiation works best if the radiation dose is high
Survival Hormone Therapy plus Radiation by Gleason Score95 5 year cure rate radiation radiation plus hormones90858075706560 3+3 3+4 4+4 4+5 5+5 Gleason Score
Cure Rates for High Risk Prostate Cancer Hormones + External + Seeds Surgery Seeds alone IJROBP 2006;66:1092 Months
10 Year Cure Rates for Patients with High Risk Prostate Cancer (PSA >20 or Gleason 8-10 or T3)Treatment Number Cure RateRadical 1,238 92%ProstatectomyRadiation plus 344 92%HormonesRadiation 265 88% Mayo Clinic Study (Cancer Jan 10, 2011)
Typical PSA Decline after External Beam Months Since Completing Radiation
Declining PSA Levels after Seed Implant PSA bounce Years
CT scan is obtained at the time of the Simulation Fiducials may be inserted before this step. CT images are then imported into the treatment planning computer
Goal = radiation zone precisely around the prostate cancer with small margin bladder prostateRadiation zone rectum
IMRT (intensitymodulatedradiation therapy) using 7 different beamsto target the prostateThe computer candetermine the optimalnumber of beams todeliver the radiationdose to hit the target andavoid other structures
After IMRT was established then IGRT(image guided) was introduced
Lower Risk of Side Effects with Image Guided IMRT compared to IMRT
Better Cure Rates with Image Guided IMRT compared to IMRT for Prostate Intermediate Risk High Risk
The most sophisticated technique for image guided IMRT is Tomotherapy.Combine a CT scan and linear accelerator to ultimate intargeting (IGRT) and ultimate in delivery (dynamic, helicalIMRT) ability to daily adjust the beam (ART or adaptiveradiotherapy)
There is significant movement of the prostate gland based on daily gas in rectum Planned target No Rectal gasPlanned target,missed badly ifrectal gas pushesthe prostate Rectal gasforward
Significant movement of the prostate gland based on daily gas in rectumInitial computer target for prostate (red circle) would have badlymissed the target if no adjustments were made based on the amountof rectal gas
Importance of daily CT targeting onTomotherapy and adjusting the treatment daily Very little bowel gas on initial study and the dose (red) targets the prostate gland closely large bowel gas on later treatment day and the dose (red) will cover half the rectum if an adjustment is Not made
If noadjustmentwas madeActualtreatment onTomotherapy
Using Tomotherapy to tightly target theprostate with very little radiation hitting the bladder or rectum
Radiosurgery for Cancer
Non Isocentric Delivery with CK Beams
Conformality: Dose Painting
SBRT Prostate Cancer / Naples-TampaExperience Feb 2005 – Apr 2008 (Naples, FL) • 164 monotherapy, 35 Gy • 168 monotherapy, 36.25 Gy • 59 EBRT + CK boost Jul 2008 – Dec 2011 (Tampa, FL) • 121 monotherapy, 36.25 Gy • 10 monotherapy, 38 GY • 12 EBRT + CK boost
PSA Response to CyberKnife Mean PSAi 6.8ng/ml Mean PSAp 0.78ng/ml97% biochemical control at 30 months median follow-up
Cure Rate after Cyberknife N = 515, Alan Katz in New York
PSA Response after Cyberknife Follow-up median 54 months (range, 7 - 78) 7 Median PSA 6 35 Gy 36.25 Gy – 36 m 0.20 ng/ml 5 – 60 m 0.10 ng/ml PSA ng/ml 4 3 By 48 months 2 – 290 of 329 pts 1 PSA < 0.5 0 0 12 24 36 48 60 72 Months
Prostate Seed Implants
A grid or template with holes every 5mm areused to line up the needles
The needles are distributed
The Mick ‘Gun’ is used to push the radioactiveseeds into the gland
The seeds are left behind, distributed throughthe gland and slowly radiate the cancer
CT scans of the prostatewill show the seeds andthe studies will be usedto calculate theradiation dose
Side Effects of Prostate Radiation
Side Effects ofProstate RadiationIs related to the sizeand area of normalstructures that areover lapped by theradiation zone…thegoal is to keep theradiation zone assmall as possible
Side Effects of Prostate Radiation With IMRT and image guided techniques the goal is to shape the radiation zone very precisely , based on the type of cancer (high Gleason might require a larger margin around the gland)
Side Effects of Prostate Radiation Radiation zoneThe structures that will get hit by radiationand have inflammation or irritation:bladder, urethra and rectum
Radiation zone Short Term Side Effects: Irritation of bladder, urethra and rectum1. Urinary frequency (getting up at night very few hours, take NSAID’s, or may benefit from medication)2. Slight burning or stinging with urination (drink cranberry juice)3. Diarrhea or more frequent, softer bowel movements, rectal soreness (take Imodium)4. Mild skin irritation is now rarely seen5. Fatigue is common
Radiation zone Long Term Side Effects: Irritation of bladder, urethra and rectumChronic radiation cystitis or proctitis: about 6% of themen will have occasional episodes of blood in the urine orwith bowel movements, this usually responds tomedication (e.g. cortisone suppositories) The risk ofserious damage to the bladder and rectum is now less than1%Impotence: about 30% of men have problems afterradiation (see the next slides)
GETUG Dose Trial for Prostate Cancer, Long Term Side EffectsScore 70Gy 80GyGI grade 3 1.9% 5.9%GU grade 3,4 2.6% 1.9% IJROBP 2011:80;1056
Long Term Side Effects from MD Anderson Dose Trial Grade 70Gy 80Gy GI grade 2 13% 26% GI grade 3 1% 7% GU grade 2 8% 13% GU grade 3 5% 4% IJROBP 2008:70:67
Long Term Side Effects in 9 Trials of SBRT for Prostate CancerGrade PercentGI Grade 3 0 – 7%GI Grade 4 0 – 1.5%GU Grade 3 1.6 – 13%GU Grade 4 0% IJROBP 2012:82:877
Quality of Life / Medicare Survey Prostate Cancer PatientsSymptom Surgery RadiationWear Pads 30% 7%Potent (< 70y) 11% 33%Potent (>70y) 12% 27%More frequent bowel 3% 10%movements J Clin Oncol 14 (8): 2258-65, 1996
Potency Rates after Prostate Cancer TreatmentTreatment Probability RangeSeeds 80% 64 – 96%Seeds + External 69% 51 – 86%External 68% 51 – 95%Radical Prostatectomy Nerve Sparing 22% 0 – 53% Standard 16% 0 – 37%Cryotherapy 11% 0 - 53% IJROBP
Potency Results after External Radiation can range from 16% to 92% Did they get hormone therapy along with the radiation? How high was the PSA prior to radiation? How good was their sexual function before?
Potency Results after External Radiation can range from 16% to 92%
Potency Results after Seeds can range from 6% to 98% Patient Age? Race? Obese or thin? How good was their sexual function before?
Potency Results after Seeds range from 6% to 98%
Responded to ViagraSurgery: 60%External Radiation: 63%Seeds: 85% JAMA 2011:306:1205
Responded to Viagra Surgery: 43% Radiation: 70 –91% General Population: 80% from other studies in the literature
Understanding Prostate Cancer Robert Miller MD www.aboutcancer.com
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