Prostate Imrt

Acute Toxicity for Prostatectomy Patients receiving y g Intensity Modulated Radiotherapy V. Kong, T. Craig, A. Bayley, R. Bristow, C. Catton, P. Chung, M. Gospodarowicz, M. Milosevic, P. Warde, C. Ménard

Introduction Radical Prostatectomy y Effective treatment for patients with favorable prognostic factors Intent of Post-Operative Radiotherapy Reduces local recurrence rate for high risk patients Used as either adjuvant or salvage therapy V. Kong, PMH Conference

Post- Post-Operative Radiotherapy Treatment Volume & Technique q Defined using bony landmark 4 Field Box V. Kong, PMH Conference

Side effects from Radiotherapy Gastrointestinal (GI) Proctitis Loose bowel movement or diarrhea Genitourinary ( ) y (GU) Urinary incontinence Increased frequency Pain/Burning senation V. Kong, PMH Conference

Advancement of Technology New consensus guideline for prostate bed g p Clinical Target Volume (CTV) definition Increase volume? -> Increase toxicity? V. Kong, PMH Conference

The need to change Treatment technique q Conformal 4 field box 62.7 Gy 55.0 Gy V. Kong, PMH Conference

Objectives To describe the development of an Intensity p y Modulated Radiotherapy (IMRT) technique for the Prostate Bed To T report th clinical dosimetric characteristics of t the li i l d i t i h t i ti f the new technique To report acute GI and GU toxicity outcomes To compare results with a historical cohort treated by 4 field box technique (4FB) V. Kong, PMH Conference

Method 50 patients accrued to prospective trial p p p V. Kong, PMH Conference

Process Flowchart Patient Education Sess o at e t ducat o Session CT Simulation Delineation of Regions of Interest (ROI) Generation of IMRT Distribution Treatment V. Kong, PMH Conference

CT Simulation Full bladder and empty rectum py Pelvic vacuum immobilization device V. Kong, PMH Conference

Clinical Target Volume Inferior CTV (ICTV) Superior CTV (SCTV) Wiltshire et al. IJROBP 2007 69(4); 1090-1099 V. Kong, PMH Conference

Planning Target Volume Planning Target Volume (PTV) Margin (mm) g g ( ) g ( ) Online guidance using soft tissue/surgical clip Chu, 2007 AP SI RL SCTV 14 13 7 ICTV 10 11 5 V. Kong, PMH Conference

Organ at Risk (OAR) Rectal Wall (RW) ( ) Bladder Wall (BW) Penile Bulb (PB) Femur V. Kong, PMH Conference

IMRT 7 field step-and-shoot distribution p Dose fractionation 66Gy in 33 fractions y V. Kong, PMH Conference

IMRT Treatment planning objectives p g j 1. Avoid irradiating rectum circumferentially to 55 Gy V. Kong, PMH Conference

IMRT Posterior Rectal Wall (pRW) (p ) 62.7 62 7 Gy 55.0 Gy V. Kong, PMH Conference

IMRT Treatment planning objectives p g j 1. Avoid irradiating rectum circumferentially to 55 Gy 2. PTV D99 ≥ 54 Gy V. Kong, PMH Conference

IMRT Treatment planning objectives p g j 1. Avoid irradiating rectum circumferentially to 55 Gy 2. PTV D99 ≥ 54 Gy 3. Maximize % of PTV receiving 95% of prescription dose – V95 i ti d V. Kong, PMH Conference

Dose Constraints Organs at Risk Metric Dose (Gy) Rectal Wall 1 cm3 ≤ 66 0 66.0 Bladder Wall 2 cm3 ≤ 67.3 Penile Bulb 0.5 cm3 ≤ 66.0 Femur 1 cm3 ≤ 55.0 V. Kong, PMH Conference

Monitoring Side Effect Acute Toxicity Scoring y g Common Terminology Criteria Adverse Events (CTCAE) v3.0 V. Kong, PMH Conference

V. Kong, PMH Conference

Monitoring Side Effect Acute Toxicity Scoring y g Common Terminology Criteria Adverse Events (CTCAE) v3.0 GI GU Diarrhea Frequency Proctitis Haematuria Cystitis Spasm V. Kong, PMH Conference

Is IMRT better? Comparison with 4FB technique p q 23 patients with acute toxicity scored using CTCAE v3.0 Dose to Rectal Wall and Bladder Wall Acute GI/GU toxicity V. Kong, PMH Conference

Result Mean PTV V95 = 95.2% (SD = 2.1) ( ) 20 18 16 14 Number 12 of 10 Patients 8 6 4 2 0 90 92 94 96 98 100 PTV V95 (%) V. Kong, PMH Conference

Result 64.0 Patient A 62.0 60.0 PTV D99 58.0 (Gy) 56.0 54.0 2 R = 0.8514 Patient B 52.0 90.0 92.0 94.0 96.0 98.0 100.0 PTV V95 (%) Mean PTV D99 = 57.8 Gy ( y (Range: 53.4 – 62.9 Gy) g y) V. Kong, PMH Conference

Result Patient A Patient B 62.7 Gy 55.0 Gy V. Kong, PMH Conference

Result Acute GI Toxicity y Score Diarrhea Proctitis GI 0 19 (38%) 17 (34%) 10 (20%) 1 25 (50%) 23 (46%) 27 (54%) 2 6 (12%) 13 (20%) 13 (26%) 3 0 0 0 V. Kong, PMH Conference

Result Acute GU Toxicity y Score Frequency Haematuria Cystitis Spasms GU 0 19 (38%) 45 (90%) 39 (78%) 27 (54%) 14 (28%) 1 24 (48%) 5 (10%) 10 (20%) 20 (40%) 28 (56%) 2 5 (10%) 0 1 (2%) 3 (6%) 6 (12%) 3 2 (4%) 0 0 0 2 (4%) V. Kong, PMH Conference

Result Comparison of Dose to Rectal Wall p 100 4FB IMRT 80 Normalized 60 Volume (%) 40 20 0 0 1000 2000 3000 4000 5000 6000 7000 Dose (cGy) V. Kong, PMH Conference

Result Comparison of Dose to Bladder Wall p 100 4FB IMRT 80 Normalized 60 Volume (%) 40 20 0 0 1000 2000 3000 4000 5000 6000 7000 Dose (Gy) V. Kong, PMH Conference

Result Comparison of Acute GI/GU Toxicity Score ≥ 2 p y 50 IMRT 4FB 40 Number 30 of Patient 20 (%) 10 0 GI GU G and GI a d GU C Square value = 5 Chi Squa e a ue 5.21 & 9 , d = 1, p < 0 05 9.77, df , 0.05 V. Kong, PMH Conference

Conclusion Avoidance of circumferential irradiation of rectum to 55Gy with minimal compromise of PTV coverage is achievable with IMRT The use of IMRT reduces acute GI/GU toxicity rate when compared with the 4FB technique Ongoing investigation to determine if improved dosimetry to OARs translates to improved late toxicity and biochemical control V. Kong, PMH Conference

Acknowledgment Dr. Kirsty Wiltshire y Dr. William Chu Clinical Trial Co ordinators Co-ordinators Debbie Tsuji Bernadeth Lao V. Kong, PMH Conference

Prostate Imrt

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