Additional Primary Tumors Detected Incidentally on FDG PET/CT at Staging in Patients with First Diagnosis of NSCLC: Frequency, Impact on Patient Management and Survival

SIMPLE SUMMARY: The improved survival rates of lung cancer patients have led to an increased number of patients experiencing multiple primary malignancies during the course of their life. Therefore, a tool that can evaluate the risk of multiple primary cancers and detect them as early as possible could be of great clinical relevance. [(18)F]fluoro-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) has been widely used and recommended as standard care for clinical staging in lung cancer by international guidelines. However, only very limited data on the detection of additional primary malignancies on FDG-PET/CT at initial staging in non-small cell lung cancer (NSCLC) patients have been published in recent years. Therefore, we aimed to assess the frequency of additional primary malignancies detected incidentally on FDG-PET/CT at staging in patients with the initial diagnosis of NSCLC. Moreover, their impact on patient management and survival was assessed. FDG-PET/CT performed for staging might be a valuable tool to identify additional primary tumors in NSCLC patients. In our study, FDG-PET/CT identified a significant number of additional primary malignancies. Upon validation, additional primary tumors might have substantial implications for patient management clinicians that they should be aware of. Early detection of additional primary tumors together with interdisciplinary patient management may lead to similar survival rates as compared to patients with NSCLC only. ABSTRACT: We aimed to assess the frequency of additional primary malignancies detected incidentally on [(18)F]fluoro-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) at staging in NSCLC patients. Moreover, their impact on patient management and survival was assessed. Consecutive NSCLC patients with available staging FDG-PET/CT between 2020 and 2021 were retrospectively enrolled. We reported whether further investigations of suspicious findings presumably not related to NSCLC were recommended and performed after FDG-PET/CT. Any additional imaging, surgery or multimodal management was considered as an impact on patient management. Patient survival was defined using overall survival OS and progression-free survival PFS. A total of 125 NSCLC patients were included, while 26 findings in 26 different patients were suspicious for an additional malignancy on FDG-PET/CT at staging. The most frequent anatomical site was the colon. A total of 54.2% of all additional suspicious lesions turned out to be malignant. Almost every malignant finding had an impact on patient management. No significant differences were found between NSCLC patients with suspicious findings versus no suspicious findings with regards to their survival. FDG-PET/CT performed for staging might be a valuable tool to identify additional primary tumors in NSCLC patients. Identification of additional primary tumors might have substantial implications for patient management. An early detection together with interdisciplinary patient management could prevent a worsening of survival compared to patients with NSCLC only.