ObjectiveTo assess different strategies for communicating to older adults about stopping cancer screening.Design4 (recommendation statement about stopping screening)×(2; time) online survey-based randomised controlled trial.SettingAustralia.Participants271 English-speaking participants, aged 65–90, screened for breast/prostate cancer at least once in past decade.InterventionsTime 1: participants read a scenario in which their general practitioner (GP) informed them about the potential benefits and harms of cancer screening, followed by double-blinded randomisation to one of four recommendation statements to stop screening: control (‘this screening test would harm you more than benefit you’), health status (‘your other health issues should take priority’), life expectancy framed positively (‘this test would not help you live longer’) and negatively (‘you may not live long enough to benefit’). Time 2: in a follow-up scenario, the GP explained why guidelines changed over time (anchoring bias intervention).MeasuresPrimary outcomes: screening intention and cancer anxiety (10-point scale, higher=greater intention/anxiety), measured at both time points. Secondary outcomes: trust (in their GP, the information provided, the Australian healthcare system), decisional conflict and knowledge of the information presented.Results271 participants’ responses analysed. No main effects were found. However, screening intention was lower for the negatively framed life expectancy versus health status statement (6.0 vs 7.1, mean difference (MD)=1.1, p=0.049, 95% CI 0.0 to 2.2) in post hoc analyses. Cancer anxiety was lower for the negatively versus positively framed life expectancy statement (4.8 vs 5.8, MD=1.0, p=0.025, 95% CI 0.1 to 1.9). The anchoring bias intervention reduced screening intention (MD=0.8, p=0.044, 95% CI 0.6 to 1.0) and cancer anxiety (MD=0.3, p=0.002, 95% CI 0.1 to 0.4) across all conditions.ConclusionOlder adults may reduce their screening intention without reporting increased cancer anxiety when clinicians use a more confronting strategy communicating they may not live long enough to benefit and add an explicit explanation why the recommendation has changed.Trial registration numberAustralian New Zealand Clinical Trials Registry (ACTRN12618001306202; Results).