Research review 046
Randomised study
Short answer
Mailing a self-sampling kit to people's homes led to higher cervical screening participation than a standard invitation letter. Importantly, part of the increase came from people who chose clinician-collected sampling after receiving the kit. The study therefore shows the effect of an invitation strategy, not merely the use of urine or vaginal self-sampling.
What did the researchers investigate?
CapU4 compared three offers: a standard invitation, an invitation with a urine sampling kit and an invitation with a vaginal self-sampling kit. Allocation was random. Researchers examined whether participants were screened within six months.
They distinguished between using the offered self-sample and participating in screening by any sampling method. This distinction matters. A kit received by post may prompt someone to book an appointment with a clinician even if they do not wish to collect the sample themselves. Counting returned kits alone would miss this part of the effect.
What did they find?
Mailed kits could also lead to clinician-collected samples
Overall screening participation was approximately 23.5% in the self-sampling groups, compared with 12.9% with a standard letter. The difference was around 10.6 percentage points, or roughly eleven additional people screened per hundred receiving the expanded offer.
Approximately half of those who responded in the self-sampling groups nevertheless chose clinician-collected sampling. The total effect was therefore greater than the proportion of returned kits suggested. Mailing urine kits was not clearly better than mailing vaginal sampling kits for increasing total participation.
Many people still did not participate. An increase from about 13 to 24 per hundred is meaningful but also means that the majority were not reached by this single offer.
How certain can we be?
Random allocation and implementation within an existing programme strengthen the trial. However, many people were excluded after allocation, and delivery problems differed between groups. Large envelopes containing kits may have been more difficult to deliver than standard letters. Postal strikes and outdated addresses could also matter.
Registers were not always up to date regarding recent screening. Results also depend on whether the analysis counts every form of screening or only the offered self-sample. Considering kit use alone makes the findings for urine sampling less convincing. Language barriers may have prevented some people from understanding the information.
Who do the findings apply to?
The study was conducted in Mayenne, Sarthe and Vendée, three areas of Pays de la Loire in France. The target group was women aged 30–65 who had not been screened for at least four years and had not responded to a previous invitation.
Originally, 14,997 people were included. After exclusions, 13,061 remained in the analysis. Some had recently been screened, had undergone hysterectomy or had other reasons for ineligibility. People not affiliated with the relevant health insurance scheme were not included.
What might this mean in everyday life?
The study supports an offer that preserves the option of both self-sampling and clinician-collected testing. For services, accurate addresses, understandable information and reliable registration systems are part of the intervention. The number of kits mailed is not the number of people who complete screening, and unused kits also have a cost.
What do we still need to know?
We need more information about people who still do not participate, including those who cannot understand the language of the information and those who never receive a package because their address is incorrect or unstable.
Different invitation methods should be compared. Researchers need to track how many people are actually screened and receive necessary follow-up. Costs and waste from unused kits must also be included. A good offer should make participation easier across languages, places of residence and life circumstances.
Sources
The publication covered by this review
Lefeuvre C, De Pauw H, Dhollander N, Le Duc Banaszuk AS, Pivert A, Boudet M et al. Mailing Vaginal or Urine Self-Sampling Kits versus Conventional Invitation Letters: A Randomized Trial to Assess the Effect on Cervical Cancer Screening Attendance. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 2025.
Other studies and professional sources mentioned in the text
Background source: Effect of Self-Sampling HPV DNA Testing on Cervical Cancer Screening in Singapore's Primary Care: Pragmatic Randomized Controlled Trial. 2026. Read the publication.
Background source: Impact of mode of offer of self-sampling to people overdue cervical screening on screening participation: a randomised controlled trial. 2025. Read the publication.
Last reviewed: 30 October 2026.
Source basis: The publication's full text.
Editorial update, 1 November 2026: Language, explanations and references were reviewed. The source-review date is stated above.