In the United States, many cancer centers advertise their clinical services directly to the public. Although there are potential public benefits from such advertising, including increased patient awareness of treatment options and improved access to care and clinical trials, there is also potential for harm through misinformation, provision of false hope, inappropriate use of health care resources, and disruption in doctor–patient relationships. Although patient education through advertising is appropriate, misleading patients in the name of gaining market share, boosting profits, or even boosting trial accrual is not. It is critical that rigorous ethical guidelines are adopted and that oversight is introduced to ensure that cancer center marketing supports good patient care and public health interests. Patients with cancer have been identified as an especially vulnerable population because of fears and anxiety related to their diagnosis and the very real need to identify optimal sources of care. Cancer organizations have a fiduciary duty and a moral and legal obligation to provide truthful information to avoid deceptive, inaccurate claims associated with treatment success. In this article, actionable recommendations are provided for both the oncologist and the cancer center’s marketing team to promote ethical marketing of services to patients with cancer. This tailored guidance for the oncology community includes explicit communication on (1) ensuring fair and balanced promotion of cancer services, (2) avoiding exaggeration of claims in the context of reputational marketing, (3) providing data and statistics to support direct and implied assertions of treatment success, and (4) defining eligible patient groups in the context of marketing for research. These recommendations for cancer centers are designed to promote ethical quality marketing information to patients with cancer.