Clinical Trial Details
— Status: Enrolling by invitation
Administrative data
| NCT number |
NCT05164874 |
| Other study ID # |
UCaenNormandie |
| Secondary ID |
|
| Status |
Enrolling by invitation |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
February 14, 2022 |
| Est. completion date |
September 2024 |
Study information
| Verified date |
November 2021 |
| Source |
Université de Caen Normandie |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
Organized breast cancer screening (OBCS) has been implemented nationwide since 2004 inFrance,
but the participation rate remains low (51%) and inequities in participation were reported.
Strategies as mobile mammography units could be effective to increase participation in OBCS
and reduce inequities, especially in underserved areas in regard to this screening. Our main
objective is to evaluate this device and to identify how to incorporate a mobile unit in the
OBCS with a view to tackle territorial inequities in OBCS participation. The project will be
conducted as a randomized controlled cluster trial in 2022-2024, in remote areas of 4 French
departments. The main intervention is to propose an appointment at the mobile unit in
complement to the current OBCS in these remote areas. In addition, few weeks before this
intervention, local actors will carry out actions to promote OBCS with mobile unit specific
information tools. This randomized controlled trial will provide a high level of evidence in
assessing the mobile unit effects on participation and inequities.
Description:
Context In most EU member states, breast cancer screening is organised with a mammography
screening. However, there are still differences in the way screening programmes are
implemented. In France, the organized breast cancer screening (OBCS) has been conducted,
nationwide since 2004. A screening mammography is offered every two years to women aged 50 to
74 at average risk for this cancer. They receive from management structures in charge of this
screening (SMS), an invitation to visit an accredited radiologist's office. A radiological
imaging of the breast with two views plus a clinical breast examination is realized. Two
different radiologists assure readings. In the last three year, the national participation
rate remains stable around 51%. In addition, studies, using ecological indices of
deprivation, highlight social and territorial inequalities: women living in disadvantaged
area or far from a radiologist's office less participate. Different strategies can be
implemented to increase participation to breast cancer screening, especially in populations
with low-income or in rural areas, who have less access to screening. Among these strategies,
mobile mammography units (MMU) seem effective. Therefore, in the French context, there is
very little evidence on how to intervene to reduce health socio-territorial inequalities in
screening, so public health decision-makers are unable to base proposals on evidence.
Intervention The main intervention will be a proposition for an appointment at the MMU in
complement to the current OBCS. This complementary mode of screening offers the possibility
for women furthest away from the radiologist's office to undergo screening in the MMU. All
women eligible for OBCS and living in the zone selected for the intervention will be invited
to participate either in a radiologist's office or in the MMU, keeping the choice of their
place of screening. The breast screening in the MMU will follow the same protocol as
screening at the radiologist's office according to national recommendations, so that the
quality level of screening proposed in the MMU will the same as in any radiologist office.
The MMU will be equipped with a latest-generation digital scenographer as well as an
ultrasound system according to the compliance rules of the specifications published by the
National Institute of Cancer. The quality of the mammographic radiographic equipment will
also be certified by the Nuclear Safety Agency.
About two weeks before the MMU is parked, local actors, will carry out actions to inform
women on the organized breast cancer screening and on the MMU. Women will receive the
timetable of these actions with the invitation to participate in screening.
Design This intervention will be conducted during two years in 2022-2024, as a prospective
randomized controlled cluster trial in the general population in the departments of Calvados,
Manche, Eure and Seine-Maritime (Normandy Region in the north west of France). The cluster of
the study is a group of IRIS (Ilots Regroupés pour l'Information Statistique). This
geographical unit is the smallest scale for which census data are available and represents an
average of 2000 inhabitants.
An algorithm was developed to constitute clusters integrating some constraints in a regional
scenario.
Aggregation of IRIS was done according to the travel time to the radiology centres, the most
distant IRIS has been selected and then merged with neighbouring IRIS, still by distance run,
until reaching areas of the expected population size. This except size is around 100 women.
Expecting a 40% participation to the MMU, 32 to 48 mammograms daily should be performed.
This algorithm was applied to all IRIS according to distance rank, until no more aggregation
was possible. 91,982 women (95.6%) and 1,067 IRIS (94.3%) were selected in the final
population in 356 clusters (with 258 created by the algorithm).
All the women constituting the target population is geolocated and geocoded. Thus, for each
woman, history of screening, the current date of screening invitation, IRIS of residence,
level of social deprivation according to an ecological deprivation index (the European
Deprivation Index) and the distance between the woman's house and the nearest approved
radiologist's office are known.
A randomization in parallel group have been perform to constitute the intervention arm (n=178
clusters) and the control arm (n=178 clusters), corresponding to 45275 in intervention arm vs
46707 in control arm.
Evaluations The overall objectives of the study are to evaluate the intervention's ability a)
to reduce the socio-territorial inequalities of participation in breast cancer screening in a
regional area (Normandy) in setting remote from radiologist's office b) to increase
participation rate and c) understand how intervention interact with contextual factors and
which causal mechanisms leading to these results in order to identify the optimal modalities
for extending the MMU at the national level.
Concerning the first two objectives, the main evaluation criterion will be participation in
screening, measured and compared between the "intervention" and "control" arm, at the
aggregate level (cluster) and individual level in intent to treat. At the aggregate level,
the comparison of screening participation will allow us to measure the raw and
age-standardized increase in participation due to the intervention. At the individual level,
multilevel logistic regressions, taking into account cluster data, allow to assess the
increase in the probability of participating in screening after adjustment of the social
deprivation, age and other available individual characteristics.
Although the calculation of the number of subjects in the study came from a pragmatic
approach, the intraclass correlation factor was estimated at 0.0083, which with an average
area size of 318.6 women gives a design effect equal to 3.63. Thus, the minimum significant
difference in participation that can be proven will be 1.5%.
Actors information action, will be prospectively registered in a dedicated database and will
be include in the global model analysis.
To furthermore explore contextual effect and to provide elements of knowledge on the causal
mechanisms contributing to the effectiveness of the intervention the quantitative analyses
will be completed by a qualitative approach inspired by the combined approaches that have
emerged in realistic randomised controlled trials, using a theory that goes beyond logic
models to describe contextual mechanisms and contingencies. An intervention theory was
developed and three auto questionnaires will respectively explore, the informed choice,
satisfaction to realized the mammography in the mammobile and the ComB Model construct
implied in the screening behaviour.
