Analysis Confirms Rectal Spacers May Enhance Biochemical Disease Control

Watch parts 1 and 2 of our conversation with Dr Collins.

The research team undertook a substantial real-world analysis using data extracted from a comprehensive electronic medical record (EMR) system. The scope of the study encompassed a population of 36,000 men who had been treated for prostate cancer over a 6-year period, between 2016 and 2022. The primary objective was to compare clinical outcomes between two distinct groups: those who received a hydrogel rectal spacer and those who did not.

The initial phase of the investigation focused on understanding the clinical decision-making process. Since the study was retrospective, the first critical step involved simply analyzing the EMR data to identify the factors that prioritized a patient for a spacer. The researchers sought to understand the priorities of the treating radiation oncologists—what clinical variables led them to select certain patients for the hydrogel intervention? This initial query provided insight into existing clinical practice patterns, revealing tendencies such as prioritizing patients with localized disease, those undergoing dose-escalated therapy like brachytherapy, or those with comorbidities that predisposed them to radiation-induced toxicity.

Following this exploratory phase, the methodology shifted to a rigorous comparative analysis to definitively test the effect of the spacer on cancer control. To ensure the scientific validity of the comparison, the investigators utilized advanced statistical techniques to create two cohorts that were meticulously matched on all relevant characteristics. This pre-matching process was essential to minimize confounding variables, creating two groups where the only major difference was the presence or absence of the rectal spacer. Once the two highly comparable groups were established, the primary statistical test, a multivariate analysis, was executed.

The multivariate analysis was designed to isolate the difference in biochemical disease-free survival (bDFS) between the men with spacers and those without. The rate of biochemical failure in the control group (no spacer) was 11%, whereas the rate in the group that received the rectal spacer was dramatically lower at 5.5%.

Crucially, the study also controlled for other major variables, confirming the robust nature of the findings. The positive impact of the spacer held true regardless of the radiation modality used (e.g., external beam versus brachytherapy), and none of the other characteristics or confounding factors for which the groups were matched ultimately explained the difference in biochemical control.