ABSTRACT
Objective: This study is a retrospective study of the outcome and the incidence of the toxicity of using intensity-modulated radiation therapy (IMRT) as the primary treatment for prostate cancer at Siriraj Hospital. Methods: Hospital records and radiotherapy medical records of prostate cancer patients treated with IMRT as the primary treatment between July 2004 and May 2009 at Siriraj Hospital were all reviewed. Seventy-five prostate cancer patients were included in the study. Patient’s biochemical failure was established at the time of prostatic specific antigen progression above the post-treatment nadir value +2 ng/ml according to the Phoenix definition. Acute and Late toxicity were assessed and scored according to the Radiotherapy Oncology Group grading system. Results: The median follow up time was 25 months (range 3 – 63 months). The two years overall survival (OS) and freedom from biochemical failure rate (FFBF) were 93.7 and 95.8%, respectively. Five patients (6.6%) developed prostatic specific antigen failure according to the Phoenix definition. The incidences of grade 2 of acute and late gastrointestinal toxicity were 12% and 2.7%, respectively. The incidences of grade 2 of acute and late genito-urinary toxicity were 61.3% and 41.3%, respectively. Conclusion: This preliminary result of using IMRT as the primary treatment for prostate cancer provides good outcomes. The FFBF and OS are comparable with other studies. The incidences of acute and late gastrointestinal toxicity are acceptable, but the incidences of acute and late genito-urinary toxicity are higher than other studies.