The Role of Cyberknife by Dr. David Spellberg

The Role of Cyberknife Stereotactic Body
Radiation Therapy in the Treatment of
Localized Prostate Cancer
David M. Spellberg M.D., FACS
Naples Urology Associates, P.A.
Naples, Florida

TREATMENT OPTIONS
• WATCHFUL WAITING
• SURGERY
• RADIATION THERAPY
• CRYOTHERAPY
• HIFU
• PROTON
• HORMONAL MANIPULATION
• CHEMOTHERAPY
• EXPERIMENTAL
© Dr. David Spellberg

RESEARCH
• INTERNET
• LIBRARY
• LOCAL CANCER SOCIETY
• SUPPORT GROUPS
• FAMILY/ FRIENDS

COMPLICATIONS OF
TREATMENT
• INCONTINENCE
• IMPOTENCE
• EJACULATION DYSFUNCTION
• BOWEL PROBLEMS
• WORSENING OF OVERALL HEALTH

PATIENT DRIVEN
• NON-INVASIVE
• MINIMAL SIDE EFFECTS
• MINIMAL DISRUPTION OF LIFE
• EFFICACY

• Frameless
Radiosurgery
• Robotics
• Image Guidance
• Advanced Treatment
Planning
CyberKnife Technology

• Precise control limits
dose
to the rectal wall
and urethra
Prostate Radiosurgery
Image courtesy of San Diego CyberKnife Center

• Patient lies comfortably on the
couch while the CyberKnife robot
moves, images and treats.
• Treatments typically last 1 hour
• Most patients require no sedation
allowing them to depart at the
completion of their treatment
CyberKnife Treatment Delivery

Radiation Options
Convenience Invasive Toxicity Efficacy
IMRT Low No Mod High
LDR
BrachyTx
High Yes X 1 Mod High
HDR
BrachyTx
Moderate Yes X 2 Mod High
CK High No Very Low TBD

SEQUENCE OF EVENTS
• PATHOLOGY REVIEW
• CT/BS REVIEW
• DISCUSSION OF TREATMENT
OPTIONS
• FIDUCIAL PLACEMENT
• CYBERKNIFE TREATMENT

FIDUCIAL PLACEMENT
• NPO
• IV SEDATION
• TRUS GUIDED TEMPLATE
• ANTIBIOTICS

• Precise control limits
dose to the rectal
wall
and urethra
• Automatic correction
for target motion
during treatment
Prostate Radiosurgery
Footage courtesy of St. Anthony’s Hospital

Accuray Confidential

• The prostate moves during treatment
240 seconds of Beam on time
motion

CyberKnife®
Treatment of Prostate
Cancer

Prostate PTV: gland expanded 5 mm in each
direction except posteriorly where it is expanded 3
mm

BED Calculations
• External Beam Radiation Therapy / HDR
– BED = nd [ 1 + (d/ α/β) ]
• Low Dose Rate Permanent Decaying Implants
– BED = (Ro/ λ) { 1 + [ Ro/(μ+ λ)(α/β)] }
• Definitions of parameters
n = # fractions
d = daily dose
Ro = initial dose rate of implant
λ = radioactive decay constant = 0.693/T1/2
T1/2 = radioactive half-life of isotope
μ = repair rate constant = 0.693/t1/2
t1/2 = tissue repair half-time

Calculating BED For Low Risk CaP
Monotherapy Treatment Regimens
• Biologically Equivalent
Dose
• BED = D (1 + d/alpha beta
ratio)
• D = total dose
• d = dose/fraction
• alpha/beta ratio =
1.5 for prostate
3 for late effects
10 for acute effects
• 81Gy IMRT/ 45fx / 9 weeks
(BED 1.5 = 178.2, BED 3 = 129.6 )
• HDR monoTx @ 9.5Gy X 4fx
(BED 1.5 = 278.7, BED 3 = 158.3)
(BED 1.5 = 229.1, BED 3 = 131.7)
(BED 1.5 = 253.7, BED 3 = 148.6)
• Cyberknife monoTx @ 7Gy X 5fx
(BED 1.5 = 198.3, BED 3 = 116.7 )
• Cyberknife monoTx @ 7.25Gy X 5fx
(BED 1.5 = 211.5, BED 3 = 123.9 )© Dr. David Spellberg

Dose Calculations for Cyberknife
Stereotactic Body Radiation Therapy
• For CK, one can fractionate the therapy yet remain
convenient and non-invasive for the patient
• CK doses are most like HDR, since the dose/fraction,
total doses and time factors are similar
• SHARP trial from Virginia Mason Hospital with
good results (33.5Gy/5fx)
• Thus, since we have intermediate and long term
results with HDR, CK appears to be a well founded
treatment option

Basic Demographics
• Ages 62 to 85
• Stage cT1cNoMo to cT2bNoMo
• All patients treated between 12/07/2004
and 12/31/2007
• Total number of Patients = 213

Hormonal Therapy
• 186 Patients treated without Hormonal
therapy
• 27 Patients treated with Neoadjuvant
Hormonal Therapy

Histology
Gleason grade 3 + 3 = 172 Patients
Gleason grade 4 + 4 = 1 Patient
Gleason grade 5 + 4 = 1 Patient

Prostate Volumes
Range = 15.5cc to 109cc
Mean initial volume = 45.7 cc
Median initial volume = 46.1 cc

Prostate Cyberknife MonoTx
Dose
Mean Dose = 3503 cGy (n=162)
Median Dose = 3500 cGy
Range = 3500cGy to 3755 cGy
Number of Fractions = 5

Initial PSA’s
Range = 1.1 to 17.2 ng/ml
Mean initial PSA = 5.87 ng/ml
Median initial PSA = 5.75 ng/ml

PSA Response to Cyberknife
0
1
2
3
4
5
6
7
8
iPSA 1 mo 3 mo 6 mo 9 mo 12 mo 15 mo 18 mo 21 mo 24 mo 36 mo
Mean PSA
+HTx PSA
-HTx PSA

Acute Toxicity
• Urinary hesitancy, urgency, frequency (Day 3-10)
• Tenesmus/ rectal discomfort (Day 5-8)
• Diarrhea (Day 5-8)
• Rx: Flomax
Lomotil
Decadron
Anusol-HC supp.

Acute Toxicity Scoring
(IPSS/RAS/SHIM)
• Baseline, days 2 and 5, post-treatment day 10,
1 month and 4 months
• Acute effects generally return to baseline by 1
months
• Urinary symptoms more marked in patients
with IPSS baseline scores >20
• No urethral strictures/ persistent rectal
bleeding observed

IPSS Scores After Cyberknife
SBRT
0
5
10
15
20
25
30
35
Overall Low (0-10) Mod(11-20) High(21-35)
Day 0
Day 2
Day 5
Day 10
1 Month
4 Month
12 Month
24 Month
36 month

RAS and SHIM Scores after
Cyberknife SBRT
0
5
10
15
20
25
RAS Scores Overall SHIM
Scores
High SHIM
(20-25)
Day 0
Day 2
Day 5
Day 10
1 Month
4 Month
12 Month
24 month
36 month

Summary
• Cyberknife is a new and innovative treatment
delivery technique for prostate cancer.
• Cyberknife monotherapy produces an early decline
of PSA’s in low risk patients.
• The acute toxicity of Cyberknife monotherapy is
very minimal compared to other radiation treatments.
• Cyberknife therapy is a noninvasive and convenient
treatment option for patients with early stage prostate
cancer.
• Prostate cancer patients treated with Cyberknife
should continued to be enrolled and followed in
research protocols, and the data collectively
analyzed.

The Role of Cyberknife by Dr. David Spellberg

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