The Role of Cyberknife Stereotactic Body Radiation Therapy
The Role of Cyberknife Stereotactic Body Radiation Therapy in the Treatment of Localized Prostate Cancer David M. Spellberg M. D. , FACS
Radiation Options Convenience Invasive Toxicity Efficacy IMRT Low No Mod High LDR Brachy. Tx High Yes X 1 Mod High HDR Brachy. Tx Moderate Yes X 2 Mod High CK High No Very Low TBD Jay L. Friedland, M. D.
Cyber. Knife Technology • Frameless Radiosurgery • Robotics • Image Guidance • Advanced Treatment Planning Jay L. Friedland, M. D.
Cyber. Knife Treatment Delivery Jay L. Friedland, M. D. • Patient lies comfortably on the couch while the Cyber. Knife 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
Prostate Radiosurgery • Precise control limits dose to the rectal wall and urethra Image courtesy of San Diego Cyber. Knife Center Jay L. Friedland, M. D.
Prostate Radiosurgery • Precise control limits dose to the rectal wall and urethra • Automatic correction for target motion during treatment Footage courtesy of St. Anthony’s Hospital Jay L. Friedland, M. D.
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/T 1/2 = radioactive half-life of isotope μ = repair rate constant = 0. 693/t 1/2 = tissue repair half-time Jay L. Friedland, M. D.
Calculating BED For Low Risk Ca. P Monotherapy Treatment Regimens • • • 81 Gy IMRT/ 45 fx / 9 weeks Biologically Equivalent Dose (BED 1. 5 = 178. 2, BED 3 = 129. 6 ) BED = D (1 + d/alpha beta • HDR mono. Tx @ 9. 5 Gy X 4 fx ratio) (BED 1. 5 = 278. 7, BED 3 = 158. 3) D = total dose d = dose/fraction • HDR mono. Tx @ 8. 55 Gy X 4 fx alpha/beta ratio = (BED 1. 5 = 229. 1, BED 3 = 131. 7) 1. 5 for prostate • HDR mono. Tx @ 7. 25 Gy X 6 fx 3 for late effects (BED 1. 5 = 253. 7, BED 3 = 148. 6) 10 for acute effects • Cyberknife mono. Tx @ 7 Gy X 5 fx NCH Hospital, Naples, FL (BED 1. 5 = 198. 3, BED 3 = 116. 7 ) • Cyberknife mono. Tx @ 7. 25 Gy X 5 fx (BED 1. 5 = 211. 5, BED 3 = 123. 9 ) Jay L. Friedland, M. D.
Dose Calculations for Cyberknife Stereotactic Body Radiation Therapy • For CK, one can fractionate 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. 5 Gy/5 fx) • Thus, since we have intermediate and long term results with HDR, CK appears to be a well founded treatment option Jay L. Friedland, M. D.
Prostate PTV: gland expanded 5 mm in each direction except posteriorly where it is expanded 3 mm Jay L. Friedland, M. D.
Basic Demographics • Ages 62 to 85 • Stage c. T 1 c. No. Mo to c. T 2 b. No. Mo • All patients treated between 12/07/2004 and 5/25/2007 • Total number of Patients = 162 Jay L. Friedland, M. D.
Hormonal Therapy • 135 Patients treated without Hormonal therapy • 27 Patients treated with Neoadjuvant Hormonal Therapy Jay L. Friedland, M. D.
Histology Gleason grade 3 + 3 Gleason grade 3 + 4 Gleason grade 4 + 3 Gleason grade 4 + 4 Gleason grade 5 + 4 Jay L. Friedland, M. D. = = = 121 Patients 31 Patients 8 Patients 1 Patient
Prostate Volumes Range = 15. 5 cc to 109 cc Mean initial volume = 45. 7 cc Median initial volume = 46. 1 cc Jay L. Friedland, M. D.
Prostate Cyberknife Mono. Tx Dose Mean Dose = 3503 c. Gy (n=162) Median Dose = 3500 c. Gy Range = 3500 c. Gy to 3755 c. Gy Number of Fractions = 5 Jay L. Friedland, M. D.
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 Jay L. Friedland, M. D.
PSA Response to Cyberknife Jay L. Friedland, M. D.
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. Jay L. Friedland, M. D.
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 Jay L. Friedland, M. D.
IPSS Scores After Cyberknife SBRT Jay L. Friedland, M. D.
RAS and SHIM Scores after Cyberknife SBRT Jay L. Friedland, M. D.
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. Jay L. Friedland, M. D.
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