3302 - Characterizing the Consult to CT-Simulation Interval in the Setting of Screening Colonoscopy Prior to Prostate Radiotherapy in a VA Patient Population
Presenter(s)
J. Y. Lee1, B. Robison2, A. Sekhon2, C. Kan Jr2, K. D. Kelley2, and A. M. S. Kumar1,2; 1Department of Radiation Oncology, University Hospitals Seidman Cancer Center, Cleveland, OH, 2Department of Radiation Oncology, Louis Stokes VA Medical Center, Cleveland, OH
Purpose/Objective(s):
78.3% of prostate cancer diagnoses occur between ages 45-74, coinciding with the recommended age range for screening colonoscopy. Radiation oncologists generally recommend completion of screening colonoscopy prior to radiation to mitigate risk of colorectal injury in the initial years after treatment. This retrospective cohort study analyzed the duration of the interval between initial radiation consult and CT-simulation (sim) with a focus on patients who underwent screening colonoscopy during this interval.
Materials/Methods:
Patients who received definitive radiation for prostate cancer at the Cleveland Veterans’ Affairs Hospital between 2021 and 2025 were identified from treatment records in Varian ARIA. Demographic information, NCCN risk stratification, comorbidities, androgen deprivation therapy (ADT) use; dates of consult, colonoscopy, fiducial/hydrogel spacer placement, and sim were recorded. Hospital admissions and emergency department (ED) visits that occurred between consult and sim were noted. Statistical analyses were conducted in R. Outliers were omitted by Tukey’s fences method.
Results:
352 patients received definitive prostate radiotherapy at the Cleveland VA between 2021 and 2025. 29% were due for screening colonoscopy at time of consult; 95% of these patients proceeded with screening colonoscopy. Among patients who underwent screening colonoscopy, 68% received ADT and 11.5% received prostate fiducial/spacer placement.
Median time from consult to sim was 37 days in the non colonoscopy group and 65.5 days in the colonoscopy group (Mann-Whitney U = 5367.5, two-tailed, p = 2.608e-10; U = 7241.5, p = 2.934e-9 with outliers included). Frequencies of hospital admission and ED visit did not differ significantly between groups (Chi-square = 0.082, 1 degree of freedom, two-tailed p = 0.7747; two-tailed p = 0.1013 by Fisher’s exact test, respectively).
Within the colonoscopy group, median time from consult to sim was 63 days among patients who did not undergo fiducial/spacer placement and 72 days among patients who underwent fiducial/spacer placement (Mann-Whitney U = 234.5, p = 0.0561; U = 341.5, p = 0.1488 with outliers included). Within the colonoscopy group, median time from consult to sim was 63 days among patients who did not receive ADT and 68 days among patients who received ADT (Mann-Whitney U = 867, p = 0.6133; U = 987, p = 0.8754 with outliers included).
Conclusion:
Screening colonoscopy during the consult to sim interval was associated with longer duration of the interval. Fiducial/spacer placement and ADT were not associated with increase in interval duration within the colonoscopy group. Further analysis is needed to identify factors that are associated with prolonged consult to sim interval among the patients in this cohort who underwent screening colonoscopy.