Predictors of Multidomain Decline in Health-Related Quality of Life After Stereotactic Body Radiation Therapy (SBRT) for Prostate Cancer


      Previous work has demonstrated the impact of stereotactic body radiation therapy (SBRT) on solitary domains of health related quality of life (HRQOL). However, a global assessment of the subset of patients that have multi-domain declines have not been performed to date. Herein, we report the on large prospective cohort of men with prostate cancer treated with SBRT and assess predictors of multi-domain global HRQOL declines longitudinally.


      Between January 2008 and September 2014, 830 consecutive men were treated with SBRT as part of a prospective trial at a single institution. Prospective Health Related Quality of Life (HRQOL) data were collected via the EPIC-26, including 5 major domains of urinary irritative, urinary incontinence, bowel, sexual, and hormonal. Within each HRQOL domain and at each time point, a single fold “Minimally Important Difference” (MID) decline (1x MID) and two fold MID (2x MID) were recorded. We then identified patients with multi-domain declines that occurred in 4 or 5 of the 5 domains. Predictors of multi-domain decline were assessed using univariable and multivariable logistical regression analyses.


      The median age was 69 years old, 25% were low risk, 57% were intermediate risk, and 18% were high risk. Twenty percent received ADT and 16% received supplemental standard fractionation radiation in addition to SBRT for higher risk features. With a best possible score of 100, the mean baseline urinary irritative, urinary incontinence, bowel, sexual, and hormonal scores were 91, 87, 95, 53, and 92, respectively. Depending on the time point post-SBRT, between 10-15% of patients had 1x MID multi-domain decline, and 1-5% of patients had 2x MID multi-domain declines. On multivariable analysis, early toxicity in urinary incontinence, bowel, and hormonal domains predicted 3 month and 12 month multi-domain declines. At 2, 3, and 5 year time points, there was no consistent predictor of 1x MID multi-domain decline when assessing baseline HRQOL scores, acute toxicity, age, radiation dose, use of ADT, prostate volume, or body mass index.


      SBRT for prostate cancer has been shown to have minimal impact on HRQOL over-time. However, we demonstrate that a subset of patients have global declines in HRQOL in nearly all HRQOL domains. Early toxicity predicted short to intermediate term multi-domain decline, but there were no consistent predictors of long term multi-domain decline suggesting an important area for future investigation.


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