Assessing adverse events of postprostatectomy radiation therapy for prostate cancer: evaluation of outcomes in the Regione Emilia-Romagna, Italy.
OBJECTIVE
Although the likelihood of radiation-related adverse events influences treatment decisions regarding radiation therapy after prostatectomy for eligible patients, the data available to inform decisions are limited. This study was designed to evaluate the genitourinary, gastrointestinal, and sexual adverse events associated with postprostatectomy radiation therapy and to assess the influence of radiation timing on the risk of adverse events.


METHODS
The Regione Emilia-Romagna Italian Longitudinal Health Care Utilization Database was queried to identify a cohort of men who received radical prostatectomy for prostate cancer during 2003 to 2009, including patients who received postprostatectomy radiation therapy. Patients with prior radiation therapy were excluded. Outcome measures were genitourinary, gastrointestinal, and sexual adverse events after prostatectomy. Rates of adverse events were compared between the cohorts who did and did not receive postoperative radiation therapy. Multivariable Cox proportional hazards models were developed for each class of adverse events, including models with radiation therapy as a time-varying covariate.


RESULTS
A total of 9876 men were included in the analyses: 2176 (22%) who received radiation therapy and 7700 (78%) treated with prostatectomy alone. In multivariable Cox proportional hazards models, the additional exposure to radiation therapy after prostatectomy was associated with increased rates of gastrointestinal (rate ratio [RR] 1.81; 95% confidence interval [CI] 1.44-2.27; P<.001) and urinary nonincontinence events (RR 1.83; 95% CI 1.83-2.80; P<.001) but not urinary incontinence events or erectile dysfunction. The addition of the time from prostatectomy to radiation therapy interaction term was not significant for any of the adverse event outcomes (P>.1 for all outcomes).


CONCLUSIONS
Radiation therapy after prostatectomy is associated with an increase in gastrointestinal and genitourinary adverse events. However, the timing of radiation therapy did not influence the risk of radiation therapy-associated adverse events in this cohort, which contradicts the commonly held clinical tenet that delaying radiation therapy reduces the risk of adverse events.
Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia. Electronic address: tns3b@virginia.edu.
Timothy N
TN
Showalter
Center for Research in Medical Education and Health Care, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania; Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania.
Sarah E
SE
Hegarty
Center for Research in Medical Education and Health Care, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania.
Carol
C
Rabinowitz
Jefferson School of Population Health, Thomas Jefferson University, Philadelphia, Pennsylvania.
Vittorio
V
Maio
Department of Biostatistics & Bioinformatics, Duke University School of Medicine, Durham, North Carolina.
Terry
T
Hyslop
Department of Radiation Oncology, Kimmel Cancer Center & Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania.
Adam P
AP
Dicker
Center for Research in Medical Education and Health Care, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania.
Daniel Z
DZ
Louis
D000328:Adult; D000368:Aged; D007172:Erectile Dysfunction / Q000209:etiology; D041981:Gastrointestinal Tract / Q000528:radiation effects*; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011468:Prostatectomy / Q000009:adverse effects*; D011471:Prostatic Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D018714:Radiotherapy, Adjuvant; D014549:Urinary Incontinence / Q000209:etiology; D014566:Urogenital System / Q000528:radiation effects*