IMRT for Prostate Cancer: St Luke’s Medical Center Experience
Objective: To report our experience on the use of intensity modulated radiotherapy (IMRT) in the treatment of prostate cancer, its associated acute gastrointestinal (GI) and genitourinary (GU) toxicities, the changes noted between pre-treatment and post-treatment PSA levels and 1 year actuarial survival.
Methods: Outpatient records of all patients with biopsy-proven prostate cancer treated with IMRT between February 2003 and September 2006 at St. Luke’s Medical Center Radiation Oncology Department were reviewed. Patient risks and pathologic tumor differentiation (Gleason’s score) were determined and those who underwent other procedures were identified. The Radiation Therapy Oncology Group (RTOG) scoring system was used to assess GU, GI, and bladder toxicities. Weekly evaluation was done during treatment period then every 3 months for one year following last day of treatment.
A total of 69 patients received either full dose (N=45) or partial dose (N=24) intensity modulated radiation therapy. Thirty nine (57.4%), 26 (38.2%) and 3 (4.4%) patients were in the high risk, intermediate risk and low risk categories respectively. Three percent had Gleason score of 2-4, 32.8% had 5-6, 35.8% had 7, and 28.4% had score of 8-10. Pre-treatment PSA levels were: 0-3.9 ng/mL in 9%, 4-9.9ng.mL in 20.9%, and 10-19.9ng/mL in 22.4% of patients. Forty two patients (60.9%) received total dose of >70Gy, 3 (4.3%) received 66 -68 Gy, 6 (8.7%) received 4.5-4.7 Gy, and 9 received 2.5-2.7 Gy and 3 – 3.1 Gy. Treatment portals were mostly the whole pelvis in 34 (49.3%) of patients. Acute RTOG toxicities: 33% as grade 1 and 4.3% as grade 2 GI toxicity; grade 1 GU toxicity in 36% and grade 1 bladder toxicity in 4.3%. There were no grade 3 toxicities. Post -treatment PSA converted back to normal levels in 82.4% of patients. After one year follow up, survival of patients in the different categories were: 100% in low risk, 96.2% in intermediate risk, 97.4% in high risk. Sixty seven of the 69 patients were alive on follow up.
The use of IMRT in prostate cancer is an effective option. Acute GI, GU and Bladder toxicities were manageable and mostly grade 1. Marked improvement in post-treatment PSA levels were noted. There was a 97.1% actuarial survival after one year of follow up.