Hearing About Evidence Uncertainty Cut Willingness to Take a Cancer Drug

Telling US adults about common uncertainties in the evidence on a new cancer drug's benefits and risks reduced their hypothetical decisions to take the drug, according to 2 randomized clinical trials published in JAMA Internal Medicine.

The investigators noted that cancer drugs are frequently approved based on uncertain benefits and risks that are not communicated to patients. The trials (NCT06997185 and NCT07110597) recruited an online sample of US adults, census matched for age, sex, education, income, and race and ethnicity, from May to July 2025. Participants received plain-language statements describing uncertainties about the drug.

Trial 1 randomized participants to 1 of 5 uncertainties: single-arm trial design, a population unrepresentative in terms of race and ethnicity, short study duration, a surrogate end point, or no noticeable improvement. Of 6,272 adults in the primary analysis (49.5% women), those in trial 1 reduced their hypothetical decisions to take the drug by a mean of 10.1 percentage points (pp; 95% CI, −11.7 to −8.5 pp) after learning about an uncertainty. Reductions occurred with all 5 uncertainties, including learning that it was unknown whether patients would notice an improvement (−14.1 pp) and that the drug was not studied in patients of similar race or ethnicity (−12.8 pp).

Trial 2 randomized participants to 1, 2, 3, or 4 uncertainties or to a control group. Hypothetical decisions to take the drug decreased with each additional uncertainty, demonstrating a dose-dependent effect. Learning about uncertainties also reduced perceived effectiveness and trust but did not affect worry about taking the drug.

The outcomes reflect hypothetical decisions rather than actual treatment choices. The authors concluded that learning about common uncertainties with a new cancer drug's benefits and risks reduced hypothetical decisions to take it.

Source: Cherla A, Wagner AK, Woloshin S, et al. Communicating uncertainties about the benefits and risks of new cancer drugs: two randomized clinical trials. JAMA Intern Med. Published online October 12, 2026. doi:10.1001/jamainternmed.2026.4969