More and more women are searching the Internet for medical information. Women who have been diagnosed with breast cancer search for information and participate in online communities—groups that “gather” in established online spaces to interact about their diagnoses of breast cancer. They share their own struggles and emotions with their own language: the rhetoric of breast cancer. They ask questions, share experiences, create friendships, discuss their disease processes, and present their illness narratives. However, they also create ethical dilemmas for online researchers and privacy issues as they share information that is legally protected through HIPAA. Online communities will only increase as research of online information expands through big data and predictive analytics, and more than ever before, women need to be aware of the information they share. Researchers also need to be aware, as they share the data they gather, and seek to preserve the privacy of the creators of the online data that they investigate and report. The Rhetoric of Breast Cancer provides a discussion of the complex structures of online communities, particularly those focused on medical diagnoses, and is a valuable read for patients, theorists, physicians, and researchers.