FLT PET-CT in evaluation of treatment response

Abstract

Purpose: Review published studies to investigate the value of clinical 3-deoxy-3-(18)F-fluorothymidine (FLT) positron emission tomography (PET) in predicting response to treatment.

Materials and methods: Interrogate databases to identify suitable publications between 2007 and 2013 with a minimum of five patients. Articles within the inclusion criteria were reviewed with major findings reported leading to a descriptive analysis of FLT PET in therapy response.

Results: Lesions investigated included glioma, head and neck, esophageal, lung, breast, gastric, renal, rectal, sarcomas, germ cell, lymphomas, leukemia, and melanoma resulting in a total of 34 studies analyzed. A variety of therapies were applied and dissimilar PET protocols were widespread making direct comparison between studies challenging. Though baseline, early and late therapy scans were popular particularly in chemotherapy regimes. Most studies investigated showed significantly reduced FLT uptake during or after therapy compared with pretreatment scans.

Conclusion: Current evidence suggests FLT PET has a positive role to play in predicting therapy response especially in brain, lung, and breast cancers where good correlation with Ki-67 is observed. However, careful attention must be placed in undertaking larger clinical trials where harmonization of scanning and analysis protocols are strictly adhered to fully assess the true potential of FLT PET in predicting response to treatment.

Keywords: 18F-fluorothymidine; positron emission tomography; predict; response; review; treatment.

Figure 1

Breast FLT PET-CT SUV_max reduction >39% pretreatment (lower row) compared with 10 days after start of the first cycle of chemotherapy (upper row). Drawn circles indicate lesion position on respective PET slices containing SUV_max. FLT = 3-Deoxy-3-¹⁸F-fluorothymidine, PET = positron emission tomography, CT = computed tomography, SUV = standardized uptake value, max = maximum