Texture indices of 4′-[methyl-11C]-thiothymidine uptake predict p16 status in patients with newly diagnosed oropharyngeal squamous cell carcinoma: Comparison with 18F-FDG uptake

Abstract Background: In oropharyngeal squamous cell carcinoma (OPSCC), human papillomavirus (HPV)/p16 status is important as a prognostic biomarker. Purpose: We evaluated the relationship between 4¢-[methyl-11C]thiothymidine (11C-4DST) and 18F-FDG PET texture indices and p16 status in patients with newly diagnosed OPSCC. Methods: We retrospectively reviewed the collected data of 256 consecutive, previously untreated patients with primary head and neck tumors enrolled between November 2011 and October 2019. Complete data on both 11C-4DST and 18F-FDG PET/CT studies before therapy, patients with OPSCC, and p16 status were available for 34 patients. Six of them were excluded because they did not exhibit sufficient 11C-4DST and/or 18F-FDG tumor uptake to perform textural analysis. Finally, 28 patients with newly diagnosed OPSCC were investigated. The maximum standardized uptake value (SUVmax) and 6 texture indices (homogeneity, entropy, short-run emphasis, long-run emphasis, low-gray-level-zone emphasis, and high-gray-level-zone emphasis) were derived from PET images. The presence of p16 expression in tumor specimens was examined by immunohistochemistry and compared with the PET parameters. Results: Using 11C-4DST, the expression of p16 was associated with a higher homogeneity (P = 0.012), lower short-run emphasis (P = 0.005), higher long-run emphasis (P = 0.009), and lower high-gray-level-zone emphasis (P = 0.042) values. There was no significant difference between 18F-FDG PET parameters and p16 status. Conclusion: Texture indices of the primary tumor on 11C-4DST PET, but not 18F-FDG PET, may be of value in predicting the condition’s p16 status in patients with newly diagnosed OPSCC.