e18656 Background: Medical oncology (MEDONC) requires a combination of skills in collaboration, communication, and professionalism, ultimately delivering technical and clinical knowledge in practice. Standard assessment tools (e.g. written examination, OSCE) are not effective in evaluating competencies beyond technical skills and fail to define the cancer care experience holistically. This explorative, descriptive study aims to identify the potential of unstructured, unsolicited, open access online patient reviews (OPRs) as a tool to assess physician competency. Methods: University-affiliated MEDONCs in Ontario (Canada) were selected. All OPRs were identified on RateMD using every name permutation; physician names and institutional affiliations were removed from comments. A descriptive analysis of the cohort was completed. The CanMEDS Framework, defining physician standards, was used with its hierarchy of roles, concepts, and competencies. Two reviewers, a communication studies researcher and a healthcare professional, independently assessed comments and identified common themes. Competency-level assessments were evaluated using kappa with linear weights. Results: 473 OPRs were identified for 49 MEDONCs (71% male, 29% female). Of these, 23% were written by care providers. Competencies defining roles of Medical Expert, Communicator, and Professional were most prevalent (64%, 38%, and 27% respectively). Agreement levels were high in all roles (wK = 0.71 - 1.00). Themes identified were similar in positive and negative evaluations. Most commonly discussed positive themes were knowledge translation and compassionate interpersonal skills. Most common negative themes centered on lack of humility, compassion, and communication skills. 38% of comments were marked helpful, indicating engagement with other OPRs as a key characteristic of rating tools. In addition to the physician in question, 21% of OPRs reported on healthcare delivery by staff. Conclusions: OPRs emphasize experiential competencies related to interpersonal skills and suggest an alternative format to evaluating such aspects of MEDONC competencies.[Table: see text]