Patient Reported Comparative Effectiveness of Contemporary Intensity Modulated Radiation Therapy Versus External Beam Radiation Therapy of the Mid 1990s for Localized Prostate Cancer.

INTRODUCTION: Little is known about differences in patient reported outcomes between contemporary external beam radiation therapy for localized prostate cancer that delivers higher doses of conformal radiation and older techniques. We examined sexual, urinary and bowel function between men undergoing contemporary intensity modulated radiation therapy vs those undergoing external beam radiation therapy in the mid 1990s. METHODS: Subjects were selected from 2 large population based prospective cohort studies. Main outcomes were between-group differences in adjusted mean scores at 6 and 12 months. Secondary analyses examined odds ratios comparing groups reporting a clinically significant decline in function. RESULTS: The cohort consisted of 943 men, 467 diagnosed in 2011 to 2012 and 476 diagnosed in 1994 to 1995. Men undergoing contemporary intensity modulated radiation therapy reported better bowel function at 6 months (mean difference 4.3 points, 95% CI 1.6-7.0) but not at 12 months. Patients receiving contemporary intensity modulated radiation therapy reported statistically worse but probably not clinically meaningful different urinary function at 12 months (2.7, 0.5 to 4.8 points), and no difference at 6 months. No differences in sexual function at 6 or 12 months were found. Secondary analyses demonstrated lower odds of reporting clinically meaningful declines in bowel function at 6 and 12 months and sexual function at 12 months for contemporary intensity modulated radiation therapy. However, patients receiving intensity modulated radiation therapy had higher odds of reporting clinically meaningful declines in urinary continence at 12 months. CONCLUSIONS: Despite the delivery of higher doses of radiation, men treated with contemporary intensity modulated radiation therapy reported fewer gastrointestinal and possibly fewer sexual side effects than those treated with external beam radiation therapy in the mid 1990s. However, delivery of dose escalated intensity modulated radiation therapy may cause more urinary side effects.