Disease-specific hashtags for online communication about cancer care.

6520 Background: A majority of patients and health care professionals are now online. Our hypothesis is that disease-specific cancer hashtags may be a way to access accurate health information and positive interactions. Methods: Based upon two de novo hashtags, #bcsm and #btsm, an organized system of hashtags, the cancer tag ontology (CTO) was designed in July 2013 for online use. We conducted a retrospective study of 25 hashtags used on Twitter April 2011 – September 2014 using data from Symplur, LLC. We classified up to 100 most active users of each hashtag as follows: patient; doctor; non-doctor health care professional (HCP); individual NOS (I); healthcare organization (HCO), other organization (OO); or spam. Tweet activity was analyzed quarterly for all tags. Results: During the study period, there were a total of 531,765 tweets from 77,454 users. The two original hashtags #bcsm and #btsm had the most use with 249,312 and 110,465 tweets, respectively. The other tags were used almost exclusively starting Q3 2013 onward. Overall, the most active new tags were those with organized Twitter-based chats: #ayacsm; #gyncsm; #lcsm; #mmsm; and #pancsm. These seven accounted for 93% of total Twitter activity. In the cohort, 11% were patients, 20% doctors, 3% HCP, 32% I, 30% HCO, 1% OO, and 3% spam. The most active top users were patients with an median of 46 tweets. Activity increased from 13,778 tweets in Q3 2011 to 75,960 tweets in Q3 2014. For the 23 structured tags, quarterly use increased from 18,098 tweets in Q3 2013 to 39,761 tweets in Q3 2014. Conclusions: We have demonstrated the feasibility and growth of organized, cancer-specific hashtags on Twitter used by a variety of stakeholders in cancer care. Use of the CTO indicates potential value of online interaction. Further study is needed to determine whether the CTO has any impact on access, outcomes or as a model for other areas of medicine.