Short-course intensity-modulated radiotherapy (70 GY at 2.5 GY per fraction) for localized prostate cancer: preliminary results on late toxicity and quality of life.

PURPOSE: To present our preliminary observations on the late toxicity and quality of life (QOL) of patients treated with short-course intensity-modulated radiotherapy (SCIM-RT). METHODS AND MATERIALS: Fifty-one patients were treated with SCIM-RT at the Cleveland Clinic Foundation between October 1998 and May 1999. The technique consisted of intensity-modulated radiotherapy using 5 static fields (anterior, 2 laterals, and 2 anterior obliques). Inverse plans were generated by the Corvus treatment-planning system. The treatment delivery was performed with a dynamic multileaf collimator. A total of 70.0 Gy was prescribed in all cases at 2.5 Gy per fraction to be delivered in 28 fractions over 5 and a half weeks. The location of the prostate gland was verified and adjusted daily with the BAT transabdominal ultrasound system. The median follow-up was 18 months (range: 11 to 26 months). The Radiation Therapy Oncology Group (RTOG) scales were used to evaluate late toxicity. The Expanded Prostate Cancer Index Composite (EPIC) was used to evaluate QOL. A total of 24 patients completed the EPIC questionnaire at approximately 2 years after therapy (median time from treatment to questionnaire administration: 24 months; range: 21 to 26 months). The results from the EPIC questionnaires were compared to scores from 46 patients treated during the same time period with conformal radiotherapy (CRT) to 78 Gy at 2 Gy per fraction.
RESULTS: The dose was prescribed to an isodose line ranging from 82.0% to 90.0% (mean: 87.2%). The range of the individual prostate mean doses was 73.5 to 78.5 Gy (average: 75.3 Gy). To date, only 1 patient had Grade 1 late urinary toxicity. To date, only 4 patients had Grade 1 late rectal toxicity. No Grade 2 or 3 late urinary or rectal complications have occurred. The actuarial rectal bleeding rate observed at 18 months was 7%. There were no differences in scores from the urinary, bowel, hormonal, and overall QOL domains between SCIM-RT patients and patients treated with CRT. The overall physical and mental QOL scores were also nearly identical to scores reported for the general U.S. population.
CONCLUSION: Preliminary late toxicity results up to 2 years after SCIM-RT are encouraging, with a median follow-up of 18 months (range 11 to 26 months). Late toxicity assessed by the physicians using RTOG late toxicity scores has been excellent. QOL reported by the patients using the EPIC questionnaire reveals no difference between patients treated with high-dose CRT at standard fractionation and patients treated with SCIM-RT. SCIM-RT is an alternative method of dose escalation in the treatment of localized prostate cancer. The proposed schedule significantly increases convenience to patients due to the decrease in overall treatment time.