Trial Outcomes & Findings for Impact of Bladder Depletion on Mesorectal Movements During Radiotherapy in Rectal Cancer (NCT NCT04323722)

Results Overview

The mesorectal anterior distance was measured on planning pCT and on each CBCT at predefined heights based on bone landmarks. Differences between pCT and CBCT measurements were assessed.

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

53 participants

Primary outcome timeframe

5 weeks

Results posted on

2026-06-23

Participant Flow

Participant milestones

Participant milestones
Measure	Empty and Full Bladder Planning CT scan and CBCTs with empty bladder after standard Planning CT scan and CBCTs with full bladder Empty Bladder planning CT scan and CBCTs: Patient will receive a Planning CT scan, 3 CBCTs on the first week and once a week during radiotherapy treatment with an Empty Bladder
Overall Study STARTED	53
Overall Study CT scan empty bladder	48
Overall Study CT scan full bladder	48
Overall Study CBCTs empty bladder	48
Overall Study CBCTs full bladder	48
Overall Study COMPLETED	48
Overall Study NOT COMPLETED	5

Reasons for withdrawal

Reasons for withdrawal
Measure	Empty and Full Bladder Planning CT scan and CBCTs with empty bladder after standard Planning CT scan and CBCTs with full bladder Empty Bladder planning CT scan and CBCTs: Patient will receive a Planning CT scan, 3 CBCTs on the first week and once a week during radiotherapy treatment with an Empty Bladder
Overall Study All study procedures not performed	3
Overall Study Withdrawal by Subject	2

Baseline Characteristics

Race and Ethnicity were not collected from any participant.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Empty Bladder n=48 Participants Planning CT scan and CBCTs with empty bladder after standard Planning CT scan and CBCTs with full bladder Empty Bladder planning CT scan and CBCTs: Patient will receive a Planning CT scan, 3 CBCTs on the first week and once a week during radiotherapy treatment with an Empty Bladder
Age, Continuous	65.6 years STANDARD_DEVIATION 11.3 • n=48 Participants
Sex: Female, Male Female	11 Participants n=48 Participants
Sex: Female, Male Male	37 Participants n=48 Participants
Region of Enrollment France	48 participants n=48 Participants

PRIMARY outcome

Timeframe: 5 weeks

Population: Results are presented in terms of group systematic error and standard deviation of the systematic error.

The mesorectal anterior distance was measured on planning pCT and on each CBCT at predefined heights based on bone landmarks. Differences between pCT and CBCT measurements were assessed.

Outcome measures

Outcome measures
Measure	Empty and Full Bladder n=48 Participants pCT and CBCTs in empty and full bladder conditions Empty and full Bladder pCT and CBCTs: Patient will receive a pCT, 3 CBCTs on the first week and once a week during radiotherapy treatment in empty and full bladder conditions
Difference Between the Mesorectal Anterior Distance Measured on the pCT and the Distance Measured on Each CBCT, at Different Heights Set on Bone Landmarks. High mesorectal level under empty bladder conditions	2.13 mm Standard Deviation 5.19
Difference Between the Mesorectal Anterior Distance Measured on the pCT and the Distance Measured on Each CBCT, at Different Heights Set on Bone Landmarks. Medium mesorectal under empty bladder conditions level	1.42 mm Standard Deviation 4.60
Difference Between the Mesorectal Anterior Distance Measured on the pCT and the Distance Measured on Each CBCT, at Different Heights Set on Bone Landmarks. Low mesorectal level under empty bladder conditions	0.43 mm Standard Deviation 3.03
Difference Between the Mesorectal Anterior Distance Measured on the pCT and the Distance Measured on Each CBCT, at Different Heights Set on Bone Landmarks. High mesorectal level under full bladder conditions	1.79 mm Standard Deviation 6.48
Difference Between the Mesorectal Anterior Distance Measured on the pCT and the Distance Measured on Each CBCT, at Different Heights Set on Bone Landmarks. Medium mesorectal under full bladder conditions level	1.02 mm Standard Deviation 5.36
Difference Between the Mesorectal Anterior Distance Measured on the pCT and the Distance Measured on Each CBCT, at Different Heights Set on Bone Landmarks. Low mesorectal level under full bladder conditions	-0.16 mm Standard Deviation 3.45

SECONDARY outcome

Timeframe: 5 weeks

Differences in bladder volume measured on CBCT during treatment were compared with bladder volumes on planning CT (pCT) acquired with empty and full bladder.

Outcome measures

Outcome measures
Measure	Empty and Full Bladder n=48 Participants pCT and CBCTs in empty and full bladder conditions Empty and full Bladder pCT and CBCTs: Patient will receive a pCT, 3 CBCTs on the first week and once a week during radiotherapy treatment in empty and full bladder conditions
Differences in Bladder Volumes During Treatment (CBCTs) Compared to pCT Empty bladder	73 cm3 Standard Deviation 58
Differences in Bladder Volumes During Treatment (CBCTs) Compared to pCT Full bladder	243 cm3 Standard Deviation 164

SECONDARY outcome

Timeframe: 5 weeks

Gaussian distribution models were generated for each predefined anatomical level, under both full-bladder and empty-bladder conditions, to identify the anterior safety margin required to achieve population coverage probabilities of 95%

Outcome measures

Outcome measures
Measure	Empty and Full Bladder n=48 Participants pCT and CBCTs in empty and full bladder conditions Empty and full Bladder pCT and CBCTs: Patient will receive a pCT, 3 CBCTs on the first week and once a week during radiotherapy treatment in empty and full bladder conditions
Safety Margins to Cover 95% of the Patient Population Anterior segment safety margin under empty bladder conditions	12.5 mm
Safety Margins to Cover 95% of the Patient Population Middle segment safety margin under empty bladder conditions	10.5 mm
Safety Margins to Cover 95% of the Patient Population Lower segment safety margin under empty bladder conditions	5.0 mm
Safety Margins to Cover 95% of the Patient Population Anterior segment safety margin under full bladder conditions	13.5 mm
Safety Margins to Cover 95% of the Patient Population Middle segment safety margin under full bladder conditions	13.0 mm
Safety Margins to Cover 95% of the Patient Population Lower segment safety margin under full bladder conditions	5.0 mm

Adverse Events

Empty and Full Bladder

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Dr Emmanuel RIO

Institut de Cancérologie de l'Ouest (ICO)

Phone: +33 2 40 67 99 00

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place