PURPOSE: This study was attempted to grasp the factors affecting the decision-making conflicts of preoperative cancer patients. METHODS: The subjects of this study were 110 cancer patients scheduled to undergo surgeries at K university hospital. Data were collected utilizing scales for decision-making conflicts and anxiety state, and measurement tools for attitude toward treatment and, shared decision-making. RESULTS: The level of decision-making conflicts over cancer treatment of preoperative cancer patients turned out to be slightly lower than the median. There were significant correlations between shared decision-making between physicians and patients, and quality of life which was a subdomain of attitude toward treatment. In multiple regression analysis, the most powerful predictor was the shared decision-making of physicians and patients. Overall, the explanatory power of the measured variables for decisionmaking conflicts about cancer therapy was 20%. CONCLUSION: The study highlights the importance of shared decision-making and quality of life which involves attitude toward treatment. Thereby, it is deemed to be necessary to develop intervention strategies regarding decision-making conflicts about cancer treatment in consideration of these variables.