Petroleum industry of Iran has provided one of the best opportunities for employees, but occupational exposures leading to chronic diseases such as cancer are high in the field. Ministry of Petroleum has owned an organization, which covers the personnel with health insurance, called “Petroleum Industry Health Organization” (PIHO). PIHO and Health, Safety & Environment (HSE) units play significant roles in providing the employees with health services. However, there is lack of a unique system specifying occupational cancer control. Cancer is a major cause of morbidity and mortality worldwide. On the other hand, negative impressions of cancer and heavy costs of patient’s treatment have forced the ministry to pay appropriate attention to this chronic disease. This paper aims to identify structure and design a framework for a system to occupational cancer control in Iranian petroleum industry. Due to the vast dynamic complexities (multi-dimension nature of cancer, joint exposures, and the delay between exposure and incidence) and behavioral complexities (various stakeholders and actors) in the problem, we have adopted Soft System Methodology (SSM) in order to study the current situation. We reached an agreement with the problem owner on a rich picture, CATWOE analysis, and a root definition on how this surveillance system would be considering the real world circumstances.The results were obtained through many sessions with problem stakeholders even with conflicting interests. The results revealed that it is necessary to make some changes in the actors’ information systems (occupational hygiene and medicine, hospitals and the ministry’s Pension Organization), with an emphasis on identifying and analyzing carcinogens and cancer patients in order to improve the problem situation.