Usefulness of 64Cu-ATSM in head and neck cancer: A preliminary prospective study

AIMS: ⁶⁴Cu-diacetyl-bis(N4-methylthiosemicarbazone) ( ⁶⁴Cu-ATSM) is a hypoxia-avid, positron emitter radiotracer. The primary aim of this study is to assess the efficacy of pretherapy ⁶⁴Cu-ATSM PET/CT as a prognostic factor of response to therapy. The secondary aims are to investigate if there is a difference between early and late PET/CT scans and if there is a difference between the biologic tumor volume (BTV) in radiotherapy treatment planning calculated between ⁶⁴Cu-ATSM and ¹⁸F-FDG, and to assess if ⁶⁴Cu-ATSM is a prognostic marker of disease progression. METHODS: Eleven patients with head and neck cancer treated with chemoradiotherapy were enrolled prospectively; both ⁶⁴Cu-ATSM and ¹⁸F-FDG PET/CT scans before and after treatment were obtained. The ⁶⁴Cu-ATSM scans were performed after 1 hour (early) and 16 hours (late). RESULTS: All patients had stage III or IV squamous cell head and neck cancer; 7 of 11 patients had nodal metastasis, and 22 cancer foci were detected with ⁶⁴Cu-ATSM. SUVmax was 16.2 ± 7.9, and there was no significant SUVmax difference between early and late imaging. ¹⁸F-FDG SUVmax before therapy was 15.6 ± 9.4, whereas ¹⁸F-FDG SUVmax after therapy was 1.5 ± 1.2. Sensitivity and specificity values of ⁶⁴Cu-ATSM calculated with receiver operating characteristic curves were 100% and 50% considering the SUVmax and 100% and 33% considering the volume, respectively. No difference has been found between the BTV contoured with ⁶⁴Cu-ATSM and ¹⁸F-FDG. CONCLUSIONS: The ⁶⁴Cu-ATSM scans showed high sensitivity but low specificity in predicting neoadjuvant chemoradiotherapy response. No difference was noted between early and late scans. ¹⁸F-FDG and ⁶⁴Cu-ATSM provided similar results about delineation of BTV.