Patient-reported Quality of Life in Prostate Cancer Patients Treated With 3D Conformal Intensity Modulated or Proton Beam Radiation Therapy

Limited data exist comparing contemporary technologies in the treatment of prostate cancer. 3D conformal (3DCRT), proton beam (PBT) and intensity modulated radiation therapy (IMRT) are all widely-used techniques for delivering high-dose radiation. We evaluated patient-reported outcomes (PRO) for quality of life (QOL) from three modern cohorts treated with each of these modalities. QOL data for 153 patients treated with IMRT monotherapy and collected by the PROST-QA consortium using the Expanded Prostate Cancer Index Composite (EPIC) instrument were compared to data for 94 patients treated at the Massachusetts General Hospital with PBT monotherapy and 123 patients treated at Harvard-affiliated hospitals with 3DCRT monotherapy and followed using the Prostate Cancer Symptoms Index (PCSI) instrument. PCSI scores were inverted for comparison to EPIC. Mean scores at baseline, at first follow-up (2-3 months) and at 24 months were compared using a paired t test. To maintain the overall type 1 error at 0.05 after multiple comparisons, a p value of .006 was considered significant. Clinically meaningful differences in QOL scores were defined as those exceeding half the baseline standard deviation. Distribution of Gleason score, T-stage and baseline PSA were similar in the PBT and IMRT cohorts but the 3DCRT cohort had higher baseline PSA and more patients with T3 disease. Median patient age was 69 for IMRT, 70 for 3DCRT and 64 for PBT (p < 0.0001). Treatment dose range was 75.6-79.2 Gy for IMRT, 74-82 Gy RBE for PBT and 66.4-79.2 Gy for 3DCRT. At the first survey post-treatment 3DCRT and IMRT but not PBT were associated with significant and clinically meaningful lower mean bowel QOL scores (see table); all groups had significant decreases in bowel QOL scores at 24 months. Significantly lower scores in the urinary irritation domain were also seen at first follow-up for all 3 groups but this was clinically meaningful only in patients receiving IMRT. Sexual function domain scores were all lower but not clinically meaningful at 24 months. In this nonrandomized comparison using 2 validated QOL instruments, PBT appears to be associated with better early gastrointestinal QOL compared to 3DCRT and IMRT with similar mild effects at later time points. While subject to selection bias, these preliminary data suggest transient differences in PRO between IMRT and PBT underscoring the rationale for a randomized controlled trial.Oral Scientific Abstract 30; TablePatient Reported Bowel QOL Scores at Indicated Time PointsCohortBaselineImmediate post-treatment24 months post-treatmentMean score (SD)Mean score (SD)pClinically significantMean score (SD)pClinically significantPBT95.1 (6.7)93.3 (7.6)0.061691.8 (7.9)0.0041+IMRT94.3 (10.9)78.5 (20.9)<0.0001+87.6 (17.8)<0.0001+3DCRT95.5 (6.2)88.2 (13.0)<0.0001+90.2 (9.6)<0.0001+ Open table in a new tab