A better understanding of the breast cancer online narrative is important for a clearer conceptualizing of the role of online platforms in mediating health-related support. Sentiment analysis was conducted on a breast cancer online support group regarding Tamoxifen to understand users' emotions and opinions. This analysis was then contextualized within online social support literature. Out of the 498 users, the most active users were 80% more positive than least active users, while least active users were 48% more negative than most active ones; both differences were statistically significant. The higher the stage of cancer a user had, the less likelihood that she would have posted, and if she were to post, the post would have focused on her side effects and the anxiety/sadness that tailgates those side effects. The lower the stage of cancer a user had, the more likelihood that she would have posted, additionally remained active on the forum, and encouraged more (online) social support. This finding suggests that the online support platform may provide a context that exacerbates support for like-minded users where stronger ties are created around a specific sentiment within the community with less connection from those with dissimilar sentiments to the dominant group.