Background: Therapeutic clinical decision-support systems (CDSS) are often evaluated by comparisons between CDSS options and actual practice decisions or expert opinions. Few such studies have carefully examined reasons for discordance. Methods: We reviewed 11 concordance studies from different hospitals across 8 provinces in China, published between 2017 and 2018. The studies compared IBM Watson for Oncology (WfO) therapeutic options to treatments selected by oncologists or a tumor board involved in review of cases for lung, colon, rectal, breast, gastric, and gynecological cancers. We identified given reasons for discordance and summarized themes across studies. Results: Of the 11 studies, 9 provided 1 or more reasons for discordance which could be analyzed. We found three major themes related to discordance: formulary restrictions, treatment-protocol differences, and physician or patient preferences (Table). Formulary differences between WfO and regional practices included off-label drug uses or unavailable therapies. Treatment-protocol differences included variations in regimens, such as simultaneous versus sequential treatments. Physician or patient preferences included factors such as the cost of treatment and logistics associated with various treatments. Conclusions: This study identified multiple reasons for discordance between an oncology CDSS option and oncologists’ treatment choices in China. Treatment differences arose from local formulary or protocol differences as well as provider and patient preferences. Future studies of CDSS should include reasons for discordance when assessing system performance in this manner.