Measuring common public misperceptions about cancer.

A 32 item criterion-referenced knowledge questionnaire was developed to measure the level of common misperceptions about the nature of cancer and cancer treatments held by the public. A sample of 353 respondents were contacted and agreed to complete the questionnaire through a random telephone survey technique (Random Digit Dialing). An extensive analysis of the responses to the survey was performed and supported the validity and reliability of the instrument. Results of the survey indicate that the prevalence of misperceptions held by the public is high. The total mean score correct on the questionnaire was only 17.2 out of a possible 32. No differences were found for total mean score on the questionnaire based on the respondents' age, sex, or whether they or someone close to them had ever had cancer. Statistically significant differences, however, were found for the total mean score on the questionnaire based on the respondent's level of education and how they responded to two attitudinal questions on the questionnaire. The most prevalent misperceptions about cancer related to questions about side effects from the treatment for cancer, followed by questions about proven cancer treatments and unproven or quack cancer treatments. The least prevalent misperceptions about cancer related to questions about the nature of cancer.