Assessment of tumor hypoxia by 62Cu-ATSM PET/CT as a predictor of response in head and neck cancer: a pilot study

Objective In radiotherapy and chemotherapy tumor hypoxia is recognized as a major obstacle to effective treatment. We undertook a pilot study in patients with locally advanced head and neck cancer to determine whether there is a relationship between tumor uptake of 62Cu-ATSM and response to chemoradiotherapy. Methods Seventeen patients were studied using PET/CT with 62Cu-ATSM and 18F-FDG prior to the initiation of radiotherapy and chemotherapy. All patients had locally advanced head and neck cancer (stage III or IV). Tumor uptake in all patients was measured by region of interest analysis using the maximal standardized uptake value (SUVmax). A total dose of 50.4–70.2 Gy (median 70.2 Gy) was delivered in 29–39 fractions (median 39 fractions) to tumor. In patients with (non CR) and without (CR) residual/recurrent tumors at 2-year post irradiation, the statistical significance of the differences in tumor 62Cu- ATSM SUVmax, T/M ratio, 18F-FDG SUVmax and tumor volume were analyzed using Student’s t test and Welch test. The relationship between clinical outcome and 62Cu- ATSM/18F-FDG uptake patterns was analyzed using Kruskal–Wallis test. The correlation between SUVmax of 62Cu-ATSM and 18F-FDG was compared by Spearman’s rank correlation test. Results Two of the 17 patients that were enrolled in our study were excluded from the final analysis. Of the 15 remaining patients, 9 patients were free of disease and 6 patients had residual/recurrent tumors. The SUVmax differed significantly (p\0.05) between patients with or without residual/recurrent tumor on 62Cu-ATSM PET/CT. Six of the 10 patients with tumors SUVmax [5.00 had residual/recurrent tumor, whereas all of the 5 patients with tumors SUVmax\5.00 were free of disease. There was no significant difference in FDG uptake between patients with and without residual/recurrent tumor. Conclusions The results of this pilot study suggested that 62Cu-ATSM uptake may be a predictive indicator of tumor response to chemoradiotherapy in patients with locally advanced head and neck cancer.