Value of ¹⁸F-FDG PET/CT in breast cancer with second primary malignancies

Purpose: To investigate the value of F-18-fluorodeoxyglucose positron emission tomography/computed tomography (F-18-FDG PET/CT) in breast cancer (BC) with second primary malignancies (SPMs). Materials and methods: 149 BC patients (149/1419, 10.5 %) ultimately diagnosed with SPMs were included in the study. The following data were evaluated: age, location, the treatment of the first BC, the interval between the first BC and SPMs, the maximum diameter of SPMs, the maximum standardized uptake value (SUVmax) of SPMs, and SPMs metastases. The overall survival (OS) and progression-free survival (PFS) of follow-up patients were analyzed. The diagnostic efficiency of F-18-FDG PET/CT for SPMs and consistency with the pathological findings were calculated. Results: The most common SPMs of BC was lung cancer (81/149, 54.4 %), particularly early-stage lung adenocarcinoma. There were the shorter maximum diameter of SPMs, the lower SUVmax of SPMs, and the fewer SPMs metastases in the lung cancer group than non-lung cancer group (P<0.001). The OS and PFS of the follow-up patients in the lung cancer group were longer than non-lung cancer group (P<0.001). The SPMs metastases was independent prognostic indicator of OS. The pathological grouping and the SPMs metastases were independent prognostic indicators of PFS. F-18-FDG PET/CT efficacy in diagnosing SPMs in BC patients was high. Compared with the pathological findings, the consistency was good (P = 0.010). Conclusion: Applying F-18-FDG PET/CT in BC patients might be helpful in detecting SPMs and partially predicting patient prognosis, in addition to its primary function in the diagnosis and staging of BC.