Contrasting Assessed and Perceived Risk: A Case Study of Two Rapidly Increasing Cancers in Taiwan

Abstract

There are unfortunate cases in public health where a scientifically determined assessment of risk presented to the public is neglected in favor of pre-conceived notions of risk. In clinical settings, risk perception is important but often ignored by practitioners. The consequences of this are varied and could be devastating. Most clinicians are not trained in communicating clinical risks, and patients may be forced to make decisions based on the risk they perceive rather than the actual risk. A rational decision would require full information expressed in terms of absolute risk as well as relative risk. As new media becomes more pervasive, the gap between assessed and perceived risk widens and society is paying a price for this phenomenon not being addressed. Two types of cancers are used to illustrate this point. Both have been increasing rapidly in the last 20 years in Taiwan for reasons related to risk perception. Risks from these two cancers were misread by the public, resulting in thousands of unnecessary deaths. Due to public misperceptions, the actual risk was mistakenly minimized in one instance, and unknowingly enhanced in another. Chewers of betel quid (BQ) belittle the risk of oral cancer, perceiving it is a known, future, familiar but controllable risk. Unfortunately, thousands die each year from BQ chewing because millions continue to chew. On the other hand, the fear of prostate cancer has led to screening tests that may cause physical and psychological harm. With the availability of PSA tests to detect prostate cancer, increasing numbers of elderly men pursue biopsy and treatment. Even though the actual risk from prostate cancer is small, the demand for zero risk has compelled worried patients to endure the agony of intervention and to suffer serious side effects because the treatment intended to reduce risk may instead increase morbidity and mortality. The fact that there may be substantial harm, with uncertain health benefits, from unnecessary treatment has been publicized, but clinicians have ignored fully communicating pros and cons of treatment to patients. Mainstream risk assessment, mostly for regulatory purposes, has focused on toxic substances often involving small risks at current occupational and environmental exposure levels. Most of these assessments address risk at a magnitude between one per thousand and one per million. Risks in clinical settings are often several orders of magnitude higher, such as the risk for smokers who have a one in three lifetime risk of dying from smok-ingrelated diseases. The irony is that the general public is far more concerned with risk from toxic substances than lifestyle or clinical risks. This discrepancy is a major health threat and should alarm risk assessors who are pursuing technological excellence on a continuing basis but neglecting risk communication. Effective risk communication in clinical settings should be a required discipline for clinicians. This training should address the gap between perceived risk, commonly dominated by pre-conceived notions, and actual risk, derived from evidence-based data.