Introduction: Cancer continues to be one of the world’s major health issues, with Mongolia continues to lead Asia in esophageal (100’000: 17.1) and gastric cancer incidence (100’000: 41.0). In the previous decade, 8,137 new cases of gastric cancer were reported in Mongolia. According to TNM staging, eight out of every ten people are diagnosed late, recognizing the need to improve people’s knowledge, attitudes, and practices. Methods: The survey was carried out using a questionnaire. A total of 320 participants between 17- 80 ages from the aimags of Uvs, Khovd, and Zavkhan were chosen at random for the survey, and data was collected through social media. SPSS (v28.0, SPSS Inc., Chicago, IL, USA) software was used for statistical analysis. Results: The survey included 110, 106, and 104 participants from the aimags of Uvs, Zavkhan, and Khovd. A total of 320 participants, with 20.9% (67) and 79.1% (253) being male and female respectively. The average age was 35.56±9.15 years. The participants’ mean knowledges, attitudes and practices scores were 7.54±2.7, 9.6±2.2, and 3.82±1.1 respectively in the first survey. Following the advocacy campaign, the mean knowledge, attitude, and practice scores increased to 9.3±2.7, 10.1±2.2, and 4.00±1.2, respectively. Conclusion The attitudes and practices of the participants were related to their level of knowledge. It is critical to increase health education and advocacy efforts in order to develop the appropriate attitudes and behaviors to reduce cancer-related deaths.