Methods: Secondary analysis of longitudinal data from the 1995 Maximizing Mammography Participation Trial, a large randomized interventional trial examining the effectiveness of patient reminders in increasing mammography utilization among women aged 50-79 (N=3743), belonging to the Group Health Cooperative of Puget Sound, a large Health Maintenance Organization (HMO). The trial was conducted during a time of heated scientific debate over mammography screening in women aged 40-49, when conflicting recommendations about mammography were being issued by major professional organizations. Using the decision theory concept of “ambiguity” as a theoretical framework for understanding potential behavioral and psychological consequences of scientific controversy, we performed logistic regression analyses to test several predictions about the effects of perceived controversy regarding mammography recommendations on women's subsequent mammography uptake and related perceptions.

Results: High perceived ambiguity about mammography recommendations was strongly associated with both diminished uptake of mammography over time (OR .43, 95% CI: .34–.55, p<.0001) and lower intentions for future mammography (OR .31, 95% CI: .24–.41, p<.0001). Higher perceived ambiguity also predicted greater mammography-related worry over time (OR 2.23, 95% CI: 1.53–3.25, p<.0001), but was unrelated to subsequent perceived breast cancer risk.

Conclusions: Perceptions of scientific controversy in cancer screening and prevention may have important behavioral and psychological effects. These effects should be considered in the design and implementation of interventions aimed at heightening the public's awareness of scientific uncertainty.