OBJECTIVES:: Pink October, the breast cancer awareness campaign (BCAC), occurs annually in Brazil since 2002 aiming to share information about breast cancer (BC) and raise awareness on the importance of early detection. However, information from BCAC is often incomplete, decontextualized and even out-of-date, which may misguide the public in several aspects. Traditional mass media coverage has been enhanced by social media in cancer treatment decision making and care support. Yet, there is a dearth of literature on how patients use these technologies during the treatment decision process and even less is known about whether online communication influences patient appraisals of decision making. The objective of this study is to assess social media campaigns during Pink October regarding information and education on breast cancer awareness. METHODS:: We searched Facebook using the term breast cancer. Analysis was restricted to groups related to breast cancer, operated in English or Portuguese, and publicly available. We collected breast cancer-related tweets from 01 to 31 October 2016, using Twitter’s application programming interface; each tweet was classified as an original or a retweet. Also, the Brazilian National Cancer Institute (INCA) and Ministry of Health (MoH) websites were reviewed to evaluate data on BC and BCAC. RESULTS:: We found 50 breast cancer groups from Brazil on Facebook containing a total of 12,688 members. Regarding Twitter, we found approximately 911 tweets on breast cancer by on the assessed period. Communication both in Facebook and in Twitter focused more on wearing pink, fundraising and self-exam. CONCLUSIONS:: Communication is an important tool for BC education and awareness, and social media is gaining increasing prominence in this medium; however, it still emphasizes fundraising and self-exam, not promoting any specific preventive behavior.