Objective And Subjective Risk Assessment: A Challenge To Breast Cancer Prevention

Carolyn GOTAY, University of British Columbia, Canada
SHEN H. 1 , MCCOY B. 1 , MAGER T. 1 , DAWSON M. 1

1 Scool of Population & Public Health, University of British Columbia, Vancouver Canada

Purpose: One challenge facing primary cancer prevention is individuals’ understanding of their cancer risk, and what they can do to reduce their risk. This study investigated breast cancer risk using objective and subjective risk measures. 
Methods: Participants were 395 women > 35 years old who self-referred to a breast cancer prevention educational program. They completed three breast cancer risk measures: the National Cancer Institute’s Gail Risk Score (includes personal and reproductive medical history, breast cancer in first degree relatives,  5-year breast cancer risk); Siteman Cancer Center’s “Your Disease Risk” (includes lifestyle risk behaviours, reproductive and medical history, 4-level risk); and perceived lifetime breast cancer risk (self-rated percent 0-100). Convergence among the risk measures was calculated.
Results: 30% of women were “high risk,” based on Gail, and 41% “above average” or “much above average” on Siteman; 70% were “low risk” on Gail and 52% on Siteman.  While scores on the two instruments were significantly correlated, there was considerable non-convergence: 53% of women at low Gail risk were also low risk on Siteman; and 62% of women at high Gail risk were “above average” or “much above average” on Siteman. Overall self-perceived risk was 31%. Self-perceived risk in the high Gail group varied positively and linearly according to Siteman score (p<.001); in the low Gail risk group, there was no significant relationship between self-perceived risk and Siteman risk  (p=.5).
Conclusions: Results indicate that different risk assessment tools provide varying summary risk estimates. Subjective breast cancer risk is almost three-fold population incidence.  Subjective risk perceptions in women who have lower biological risk do not reflect the increased risks of lifestyle factors.  To achieve primary breast cancer prevention, more attention is needed to understand what women know about risks and how risk perception affects risk reduction.
Funding: Canadian Breast Cancer Foundation British Columbia Yukon