Estimation of Radiation-Induced Secondary Cancer Risk in Lung Cancer Patients Following Three-Dimensional Conformal Radiotherapy

Purpose: Lung cancer treatment often involves radiotherapy, which can lead to an increased risk of secondary cancers in sensitive organs and Organs At Risk (OARs). Understanding this risk is crucial for optimizing treatment strategies and minimizing long-term adverse effects. The objective of this study is to estimate the Secondary Cancer Risks (SCRs) in sensitive organs and OARs using radiation-induced cancer risk prediction models, specifically the Biological Effects of Ionizing Radiation (BEIR) VII model and the International Commission on Radiological Protection (ICRP) model. Materials and Methods: The radiotherapy dosimetric data of 30 lung cancer patients were collected all of whom underwent Computed Tomography (CT) scans. The PCRT-3D Treatment Planning System (TPS) was used for the treatment planning process. The risks were calculated based on the dose distribution in the target volume. The models for Excess Absolute Risk (EAR) and Excess Relative Risk (ERR) values (per 100,000 person-year) were utilized to estimate SCRs in planning target volume, OARs, and sensitive organs. Results: The results indicate that, according to the BEIR VII model, the estimated EAR of cancer per 100,000 person-years was 38.39 in the heart, 35.83 in the esophagus, 5.49 in the contralateral lung, 2.17 in the liver, and 3.41 in the pancreas. Conversely, using the ICRP model, the EAR was calculated to be 58.73 in the heart, 38.78 in the esophagus, 20.48 in the contralateral lung, 3.49 in the liver, and 5.44 in the pancreas. These findings suggest that lung cancer patients treated with 3DCRT exhibit relatively high SCRs in the heart, esophagus, and contralateral lung organs in both models. Conclusion: In this study, SCRs in a range of organs in lung cancer patients treated with 3DCRT were quantified. Our findings revealed that there were comparatively high SCRs in the heart in 3DCRT of lung cancer patients. Based on the findings of the current investigation, the ICRP model SCRs are greater in comparison to the BEIR VII model. These findings underscore the importance of considering SCRs in treatment planning and highlight the need for further research to optimize radiation therapy strategies and minimize long-term risks for lung cancer patients.