Validating the reliability and validity of the Fear of Cancer Scale (FOCS) in the general population based on modified classical test theory and analyzing its risk factors

To validate the reliability, validity, and applicability of the Fear of Cancer Scale (FOCS) for identifying individuals in the entire Chinese general population at high risk for cancer-related fear, and to analyze the current status and risk factors associated with general population fear of cancer. Using the modified classical test theory, a total of 3963 participants were recruited from the entire Chinese general population from January to October 2024 to validate FOCS. Delphi expert consultation, item analysis and cognitive interview were used to validate the content and face validity of FOCS. Factor analysis and structural equation modeling were used to test the structural validity of FOCS. Cronbach alpha coefficient, Spearman-Brown coefficient were used to test the internal consistency reliability of FOCS. Multiple stepped-linear regression was used to analyze the risk factors of cancer-related fear in the general population. The FOCS of 17 items was divided into 3 dimensions: 8 items for direct fear, 6 items for indirect fear, and 3 items for latent fear. The three-factor correlation model's FOCS demonstrated strong validity (root mean square error of approximate = 0.042, goodness of fit index = 0.974, AGFI = 0.961, comparative fit index = 0.972, normed fit index = 0.965, incremental fit index = 0.972, tucker-lewis index = 0.962), reliability (Cronbach α coefficient was 0.885, Spearman-Brown coefficient was 0.674) and applicability (average completion time [298.13 ± 191.484 seconds] and effective completion rate of 91.27%). The cancer fear score of 3963 participants was 17 to 85, with M (P25, P75) was 55 (48, 63). Sex, age, occupation, and education level were found to be independent risk factors for general population cancer-related fear. The general population commonly experience significant fear of cancer-related issues, and the adjusted FOCS is effective and reliable for early identification and assessment of the level of cancer-related fear, which may provide an effective basis for cancer health education and public health services in the future.