Patients who have cancer have leveraged the Internet to gain a better understanding of their disease and connect across geographic boundaries with others facing the same challenges. Online cancer communities have developed into resources that highlight new research and evolving care pathways. Combined with increasing health literacy and social media, they have enabled some patients to become experts in their cancer. This combination of empowerment and expertise describes the new "e-patients." We reviewed the literature to identify key areas where expert e-patients have directly participated in advancing cancer medicine, as well as opportunities available to those who wish to become more involved in research advocacy. E-patients are widely acknowledged as key stakeholders in oncology by clinicians, researchers, cancer centers, government agencies, and nonprofits. Their input is vital for informing cancer care delivery, developing and launching research initiatives, creating care guidelines and pathways, and formulating policy. Expert e-patients play an expanded role in their own care and in larger conversations regarding practice, research, and policy. Clinicians can engage e-patients as partners in cancer care as we work together towards improving health care access and outcomes for people with cancer.