Currently submitted to: Journal of Medical Internet Research
Date Submitted: Aug 13, 2026
Open Peer Review Period: Aug 14, 2026 - Oct 9, 2026
(currently open for review)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Mapping the Cancer Support Ecosystem on Reddit: A Computational Analysis of Community Connections, Supportive Care Needs, and Emotional Expression
ABSTRACT
Background:
Online communities provide large-scale, real-time insights into essential concerns and needs for people affected by cancer and have become an informal extension of the broader supportive care environment.
Objective:
This study aimed to identify the structure, content, and emotions in cancer-related Reddit discussions using large-scale data and computational methods.
Methods:
We analyzed 3,206,108 cancer-related posts published across 40 subreddits from 2010 to 2025. Shared authorship and cross subreddits movement networks were constructed to examine community connections. Guided by supportive care needs frameworks and validated clinical surveys, a Large Language Model classifies posts into five key needs: informational, physical, psychological, and practical. BERTopic was used to identify topics, and a RoBERTa-based model identified seven emotions: anger, disgust, fear, joy, neutral, sadness, and surprise. Temporal trends in emotion were examined, and differences across supportive care needs were assessed using chi-square tests and Cramér’s V.
Results:
Discussion volume steadily increased during the study period (2010-2025) and author activity distribution was highly skewed. The structure of the network characterized that r/cancer served as a central hub linking general, disease-specific, and support-oriented communities. The most prominent needs were informational (n=1,467,967, 45.79%), followed by psychological (n=584,306, 18.22%), physical (n= 508,149, 15.85%), social (n=331,953, 10.35%), and practical needs (n=104,722, 3.27%). Emotional expression changed over time, with sadness, anger, disgust, and joy decreasing, while fear and surprise increased. Emotion patterns varied across need discussions. Although neutral emotion was common overall, informational needs were characterized by fear and surprise; physical needs by disgust and sadness; psychological and social needs by joy and anger; and practical needs by sadness and anger.
Conclusions:
This study suggests that online cancer discussions capture both the content of unmet needs and the emotional context in which they are experienced. These results may inform patient-centered health communication, digital supportive care interventions, and future research using social media data to monitor cancer-related needs across the cancer continuum.
Citation
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Copyright
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