FDG PET correlates weakly with HIF-1α expression in solid tumors: a meta-analysis

Background: Hypoxia-inducible factor (HIF)-1α plays a key role in hypoxic adaptation of tumor cells. Overexpression of HIF-1α is associated with tumor aggressiveness and worse prognosis in several malignancies. Presumably, expression of HIF-1a may be reflected by positron emission tomography with 2-deoxy-2 [fluorine-18] fluoro-D-glucose (18F-FDG PET). There are inconsistent data about relationships between FDG PET and HIF-1α. Purpose: To provide evident data about associations between maximum standardized uptake value (SUV_max) and HIF-1α expression in solid tumors. Material and Methods: MEDLINE, SCOPUS, and EMBASE databases were screened for relationships between SUV and HIF-1α up to August 2019. Overall, 21 studies with 1154 patients were identified. The following data were extracted from the literature: authors; year of publication; number of patients; and correlation coefficients. Results: Correlation coefficients between SUV_max and HIF-1α were in the range of −0.51–0.71. The pooled correlation coefficient was 0.27 (95% confidence interval [CI] = 0.14–0.41). Furthermore, correlation coefficients for some tumor entities were calculated. For this sub-analysis, data for primary tumors with >2 reports were included. The calculated correlation coefficients in the analyzed subgroups were as follows: head and neck squamous cell carcinoma: ρ = 0.25 (95% CI = 0.07–0.42); non-small lung cell cancer: ρ = 0.27 (95% CI = −0.14–0.67); uterine cervical cancer: ρ = −0.09 (95% CI = −0.89–0.71); thymic tumors: ρ = 0.39 (95% CI = 0.04–0.58). Conclusion: SUV_max of FDG PET correlated weakly with expression of HIF-1α both in overall sample and tumor subgroups. Therefore, FDG PET cannot be used for prediction of hypoxia in clinical practice.