Stereotactic Body Radiation Therapy for Early Stage Prostate
Stereotactic Body Radiation Therapy for Early Stage Prostate Cancer: Outcomes from a Single Institution Study Debra Freeman, MD Jay Friedland, MD Naples Radiation Oncology, PA
The Balancing Act Convenience Invasive Toxicity Efficacy IMRT Low No Low High LDR Brachy. Tx High Yes X 1 Mod High HDR Brachy. Tx Moderate Yes X 2 Low/Mod Very High SBRT High No Very Low TBD
Experience to Date l l First patient treated in Jan. 2005 Initiated Monotherapy protocol in Feb. 2005 Total patients treated: 334 Monotherapy: 276 Boost: 58 (Jan. 2005 -Apr. 2008)
Monotherapy Group (n=201) l l l At least 6 months follow-up Stage T 1 c. N 0 M 0 to T 2 c. N 0 M 0 Mean age = 69. 3 (49 -87) Mean prostate volume = 46. 3 cc Mean initial PSA = 6. 0 ng/ml Gleason score (3+3) = 150 pts (3+4) = 39 pts (4+3) = 8 pts
Hormonal Therapy l 174 Patients treated without hormonal therapy: 22% with Gleason score >7 mean prostate volume = 45 cc l 27 Patients treated with neoadjuvant hormonal therapy: 42% with Gleason score >7 mean prostate volume = 57 cc
Cyber. Knife Mono. Tx Dose Feb 2005 -Dec 2006: 7. 0 Gy X 5 fractions (35 Gy) Jan 2007 -present: (36. 25 Gy) 7. 25 Gy X 5 fractions
BED for Prostate Monotherapy Treatment Regimens 81 Gy IMRT/ 45 fx / 9 weeks BED 1. 5 = 178 BED 3 = 130 HDR mono. Tx @ 9. 5 Gy X 4 fx BED 1. 5 = 279 BED 3 = 158 HDR mono. Tx @ 8. 55 Gy X 4 fx BED 1. 5 = 229 BED 3 = 132 CK mono. Tx @ 7 Gy X 5 fx BED 1. 5 = 198 BED 3 = 117 CK mono. Tx @ 7. 25 Gy X 5 fx BED 1. 5 = 212 BED 3 = 124 CK mono. Tx @ 9. 5 Gy X 4 fx BED 1. 5 = 279 BED 3 = 158
Patient Prep
Fiducial Placement l l Cyber. Knife fiducials l Stainless steel screws l Gold seeds Our Prostate Fiducial Placement l Use stranded gold seeds (2 seeds per needle, 2 cm spacing) l Patient in dorsal lithotomy position l Place fiducials transperineally using TRUS and standard implant template l 2 needle sticks, drop off 4 seeds
Patient Prep l Low residue diet before imaging and during treatment week (bowel gas) l Fleet enema 1 to 2 hours before imaging and treatment l Empty bladder 1 to 2 hours before treatment, then drink specified volume of water
Clinical Example Treatment Planning CT CT at Time of Treatment
Contouring
PTV: gland expanded 5 mm in each direction except posteriorly where it is expanded 3 mm
Collimator Selection l 12 collimators l May use one or more collimators during a treatment session l This study used 2 collimators for all prostate treatments l l Large collimator to minimize tmt time Small collimator to paint dose conformally at interfaces Dia. (mm) 5. 0 7. 5 10. 0 12. 5 15 20 25 30 35 40 50 60 The IRIS is here! Can change collimator size for every beam
Typical Prostate Plan: This Study • 130 – 160 beams • 35, 000 – 45, 000 mu’s • prescribe to 85% isodose • Max / Min dose = 1. 20 (mean) • PTV coverage > 95% • CI = 1. 1 - 1. 25 • Treatment time: 45 - 60 minutes
Criteria of Acceptability: Rectum % Rectum Suggested Dose Limit (Gy) (2 Gy/fx) Calculated Dose Limit (Gy) (7. 25 Gy/fx, 5 fx, King) 60 40 19. 5 60 (1) (2) 29 25 70 (1) (2) 34 15 75 (1) (2) 37 5 78 (1) (2) 38 40 (50 RTOG) 1. Huang et al. , Late Rectal Toxicity: Dose-Volume Effects of Conformal Radiotherapy for Prostate Cancer, IJROBP, Vol. 54, No. 5, 1314 -1321, 2002 2. RTOG P-0126
Results
PSA Response to Cyber. Knife
PSA Response to Cyber. Knife
PSA Response to Cyber. Knife % achieving given PSA level by duration of follow-up PSA level 1 Year (62 pts) 2 Years (54 pts) 3 Years (19 pts) ≤ 1. 0 ng/ml 56% 84% 95% ≤ 0. 6 ng/ml 39% 54% 68% ≤ 0. 4 ng/ml 19% 43% 53% ≤ 0. 2 ng/ml 6% 14% 32%
Acute Toxicity l l Urinary hesitancy, urgency, frequency (Day 3 -10) Tenesmus/ rectal discomfort (Day 5 -8) Mild diarrhea (Day 5 -8) Rx: Flomax Lomotil Decadron Anusol-HC supp. Activia yogurt
AUA Scores after Cyber. Knife SBRT
AUA Scores after Cyber. Knife SBRT
GI Toxicity RAS scores show pattern similar to AUA (minimal acute change with return to baseline by 4 months) l Two pts. with documented radiation proctitis/rectal bleeding l l Developed <1 yr post-tx l Both pts. diabetic, on chronic Coumadin l Treated with argon laser therapy; bleeding resolved
SHIM Scores After Cyber. Knife SBRT
SHIM Scores After Cyber. Knife SBRT
E. D. (? ) l 82% of pts. maintained “erections sufficient for intercourse” at 3 yrs. (based on question #2 of SHIM)
Summary l l Cyber. Knife monotherapy appears to produce a reasonable early decline of PSA in low risk patients. The acute toxicity of Cyber. Knife monotherapy is acceptable. Late toxicity is thus far extremely low. Cyber. Knife is a noninvasive and convenient treatment option for patients with early stage prostate cancer. Prostate cancer patients treated with Cyber. Knife should optimally be enrolled on clinical research protocols. Funded protocols are currently available.
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