Background
Short-video platforms have become a major source of cancer prevention information in China. However, it remains unclear whether high-quality cancer prevention content is effectively disseminated through user engagement mechanisms, particularly across platforms with distinct content formats, recommendation algorithms, and user demographics.
 
Objectives
To assess the quality and thematic characteristics of cancer prevention–related videos on major Chinese short-video platforms and to examine the associations between video quality, user engagement, and content features.
 
Methods
We conducted a cross-sectional content analysis of 495 cancer prevention–related videos collected from three widely used Chinese platforms: Bilibili, Kwai, and TikTok (Douyin). Video quality was independently evaluated using multiple validated instruments, including the JAMA Benchmark Criteria, modified DISCERN (mDISCERN), Health On the Net principles (HON), Patient Education Materials Assessment Tool (PEMAT), Video Information and Quality Index (VIQI), Global Quality Score (GQS), and Medical Quality–Video Evaluation Tool (MQ-VET). Videos were further categorized by prevention level (primary, secondary, or tertiary), uploader characteristics, and presentation features. Given the ordinal nature and non-normal distribution of quality scores, non-parametric statistical methods were applied. Platform-level differences were examined using Kruskal-Wallis tests, and Spearman rank correlation coefficients were used to assess monotonic associations between quality scores and user engagement metrics.
 
Results
Of the 495 videos analyzed, 349 (70.5%) addressed primary prevention, 151 (30.6%) secondary prevention, and 108 (21.9%) tertiary prevention. Significant platform-level differences were observed in video length, quality scores, and user engagement metrics (all p < 0.01). Videos on Bilibili were generally longer and achieved higher quality scores across multiple instruments, whereas videos on Kwai and TikTok generated substantially higher levels of user engagement. Overall, the quality of cancer prevention content was moderate, with only a small proportion of videos meeting high-quality benchmarks across multiple assessment tools. Strong correlations were observed among different quality assessment instruments, indicating high internal consistency in quality measurement. In contrast, quality scores showed weak and inconsistent associations with user engagement indicators, including likes, shares, comments, and collections, both overall within platform-specific analyses. Notably, video duration showed consistent positive correlations with multiple quality scores, suggesting that higher-quality cancer prevention information was more commonly conveyed in longer-format videos.
 
Conclusions
Across major Chinese short-video platforms, user engagement metrics do not reliably reflect the quality of cancer prevention information, revealing a systematic decoupling between evidence-based content and algorithm-driven dissemination. This misalignment poses a governance challenge for digital cancer prevention, as platform recommendation systems and interaction signals fail to consistently elevate high-quality, guideline-concordant information. In the context of WHO and IARC priorities emphasizing primary cancer prevention, health equity, and the responsible use of digital technologies, these findings underscore the need for stronger platform-level accountability mechanisms. Policy-relevant strategies may include the integration of quality-based signals into recommendation algorithms, transparent labeling or certification of evidence-based health content, and closer collaboration between public health institutions and digital platforms. Strengthening algorithm governance and misinformation safeguards is essential to ensure that short-video ecosystems support, rather than undermine, population-level cancer prevention efforts in the digital age.

Flowchart of video selection and inclusion across three Chinese short-video platforms