Radiation Therapy for Prostate Cancer
Robert Miller MDwww.aboutcancer.com
NCCN.org
Prostate Guidelines
1. Low risk of extracapsular spread, then external beam or seeds alone
2. Intermediate risk then some (or all) of the radiation should be by external
3. High risk then hormone therapy should be added to the radiation
4. External beam should be daily image guided intensity modulated (IGRT)
5. Need high dose radiation (75 to 81 Gy)
The prostate gland has a capsule around it, and cancers arise close to the capsule, the cancer may invade through the capsule
Age: 67 / Stage T1c / Gleason 6 / PSA 5 =
27.6% risk of extracapsular spread
Age: 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
External beam > 72Gy
External beam < 72Gy
Surgery or Seeds
Prostate Cures Rates by Treatment and Dose
Months
IJROBP 2004; 58:25
Years
Prostate Cancer Relapse Rate by Radiation Dose
< 72Gy
72 - 82Gy
82Gy
Kupelian. IJROBP 2008:71:16
Salvage (postOp) radiation works best if the radiation dose is high
60
65
70
75
80
85
90
95
3+3 3+4 4+4 4+5 5+5
5 year cure rate radiation
radiation plus hormones
Survival Hormone Therapy plus
Radiation by Gleason Score
Gleason Score
Cure Rates for High Risk Prostate Cancer
Months
IJROBP 2006;66:1092
Seeds alone
Surgery
Hormones + External + Seeds
10 Year Cure Rates for Patients with High Risk Prostate Cancer
(PSA >20 or Gleason 8-10 or T3)
Mayo Clinic Study (Cancer Jan 10, 2011)
Treatment Number Cure Rate
Radical Prostatectomy
1,238 92%
Radiation plus Hormones
344 92%
Radiation 265 88%
Typical PSA Decline after External Beam
Months Since Completing Radiation
Declining PSA Levels after Seed Implant
PSA bounce
Years
Evolving Radiation
Technology
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
bladder
Radiation zone
prostate
rectum
Goal = radiation zone precisely around the prostate cancer with small margin
IMRT (intensity modulated radiation therapy)
using 7 different beams to target the prostate
The computer can determine the optimal number of beams to deliver the radiation dose to hit the target and avoid 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
Combine a CT scan and linear accelerator to ultimate in targeting (IGRT) and ultimate in delivery (dynamic, helical IMRT) ability to daily adjust the beam (ART or adaptive radiotherapy)
The most sophisticated technique for image guided IMRT is Tomotherapy.
There is significant movement of the prostate gland based on daily gas in rectum
Planned target
Rectal gas
No Rectal gas
Planned target, missed badly if rectal gas pushes the prostate forward
Significant movement of the prostate gland based on daily gas in rectum
Initial computer target for prostate (red circle) would have badly missed the target if no adjustments were made based on the amount of rectal gas
Importance of daily CT targeting on Tomotherapy 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 no adjustment was made
Actual treatment on Tomotherapy
Using Tomotherapy to tightly target the prostate with very little radiation hitting
the bladder or rectum
Radiosurgery for Cancer
Cyberknife Radiosurgery
Non Isocentric Delivery with CK Beams
Conformality: Dose Painting
SBRT Prostate Cancer / Naples-Tampa Experience
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
97% biochemical control at 30 months median follow-up
Mean PSAi 6.8ng/mlMean PSAp 0.78ng/ml
Cure Rate after Cyberknife
N = 515, Alan Katz in New York
PSA Response after Cyberknife
Follow-up median 54 months (range, 7 - 78)
Median PSA– 36 m 0.20 ng/ml
– 60 m 0.10 ng/ml By 48 months
– 290 of 329 pts
PSA < 0.5 0 12 24 36 48 60 72
0
1
2
3
4
5
6
735 Gy36.25 Gy
Months
PS
A n
g/m
l
Prostate Seed Implants
A grid or template with holes every 5mm are used to line up the needles
The needles are distributed
The Mick ‘Gun’ is used to push the radioactive seeds into the gland
The seeds are left behind, distributed through the gland and slowly radiate the cancer
CT scans of the prostate will show the seeds and the studies will be used to calculate the radiation dose
Side Effects of Prostate Radiation
Side Effects of Prostate Radiation
Is related to the size and area of normal structures that are over lapped by the radiation zone…the goal is to keep the radiation zone as small 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
The structures that will get hit by radiation and have inflammation or irritation: bladder, urethra and rectum
Radiationzone
Short Term Side Effects: Irritation of bladder, urethra and rectum
Radiationzone
1. 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 seen
5. Fatigue is common
Radiationzone
Chronic radiation cystitis or proctitis: about 6% of the men will have occasional episodes of blood in the urine or with bowel movements, this usually responds to medication (e.g. cortisone suppositories) The risk of serious damage to the bladder and rectum is now less than 1%
Impotence: about 30% of men have problems after radiation (see the next slides)
Long Term Side Effects: Irritation of bladder, urethra and rectum
GETUG Dose Trial for Prostate Cancer, Long Term Side Effects
IJROBP 2011:80;1056
Score 70Gy 80Gy
GI grade 3 1.9% 5.9%
GU grade 3,4 2.6% 1.9%
Long Term Side Effects from MD Anderson Dose Trial
IJROBP 2008:70:67
Grade 70Gy 80Gy
GI grade 2 13% 26%
GI grade 3 1% 7%
GU grade 2 8% 13%
GU grade 3 5% 4%
Long Term Side Effects in 9 Trials of SBRT for Prostate Cancer
IJROBP 2012:82:877
Grade Percent
GI Grade 3 0 – 7%
GI Grade 4 0 – 1.5%
GU Grade 3 1.6 – 13%
GU Grade 4 0%
Quality of Life / Medicare Survey Prostate Cancer Patients
Symptom Surgery Radiation
Wear Pads 30% 7%
Potent (< 70y) 11% 33%
Potent (>70y) 12% 27%
More frequent bowel movements
3% 10%
J Clin Oncol 14 (8): 2258-65, 1996
Potency Rates after Prostate Cancer Treatment
Treatment Probability Range
Seeds 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 2002:54:1063
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 External Radiation can range from 16% to 92%
Patient Age? Race? Obese or thin? How good was their sexual function
before?
Potency Results after Seeds can range from 6% to 98%
Potency Results after Seeds range from 6% to 98%
Responded to Viagra
Surgery: 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 MDwww.aboutcancer.com