Safety and quality of public chatbots for lung cancer prognostic information: a comparative evaluation
To compare the safety, accuracy, empathy, reliability, information quality, and readability of five publicly accessible large language model chatbots when answering patient-facing lung cancer prognostic questions under standardized single-turn English prompting. In this Chatbot Health Advice Reporting Transparency-guided cross-sectional evaluation, 53 standardized English prompts were submitted once to ChatGPT, Gemini, Copilot, DeepSeek, and Doubao through official web interfaces during April 1–21, 2026. Five blinded raters assessed 265 responses for safety, accuracy, empathy, DISCERN, EQIP, JAMA benchmark criteria, Global Quality Scale, and readability. Paired repeated-measures analyses were used. Inter-rater agreement was good to excellent. Safety differed significantly across models (Cochran’s Q = 14.089, df = 4, p = 0.007). Gemini generated the highest proportion of safe responses (48/53, 90.6%), whereas DeepSeek generated the lowest (33/53, 62.3%). The only adjusted pairwise safety difference that remained significant was Gemini versus DeepSeek (adjusted p = 0.023). Accuracy, empathy, reliability, information quality, and readability also differed significantly across models (all p < 0.001). Gemini showed the most favorable descriptive profile for safety, accuracy, empathy, and reliability, while Copilot produced the most readable responses. Public-facing chatbots differed substantially in safety, reliability, communication quality, and readability. These findings are time-, interface-, and prompt-dependent. Chatbots may support general patient education but should not replace individualized clinician-led prognostic communication.