Prediction on Recurrence for Stage I Non-Small Cell Lung Carcinoma by Tl-SPECT and FDG-PET

Background: The purpose of this study is to clarify the utility of thallium-201 single photon emission tomography (Tl-SPECT) for predicting local recurrence after stereotactic radiotherapy (SRT) by comparing it with 18fl udeoxyglucose-positron emission tomography (FDG-PET). Since Tl-SPECT can be performed at general hospitals, the ability of Tl-SPECT to predict local recurrence after SRT is clinically important. Methods and materials: Between January 2007 and December 2011, 78 patients with stage I non-small cell lung carcinoma underwent Tl-SPECT and FDG-PET before SRT. The median follow-up period was 28 months (range, 6 to 66 months), and the subjects’ median age was 80-years-old (range, 50 to 90-years-old). Results: During the analysis of factors associated with recurrence outside of the radiation fi eld and all recurrent lesions, correlations were detected between recurrence and the early and delayed standardized uptake values obtained during FDG-PET. Although it is not possible to predict the local effects of radiation based on a tumor’s FDG uptake, the latter parameter is useful for predicting the overall risk of recurrence. This indicates that the recurrence rate could be reduced by performing chemotherapy after radiotherapy in cases exhibiting strong FDG uptake. It is suggested that tumors that exhibit a retention index of >50.68 on Tl-SPECT often recur. Conclusion: Local recurrence after SRT can be predicted by Tl-SPECT. Therefore, it is expected that the use of Tl-SPECT will lead to the identifi cation of patients that are at high risk of local recurrence. Such patients could be given more intensive treatment, which would lead to an improvement in the local control rate.