18F-FDG Uptake at Initial Staging of the Adrenocortical Cancers: A Diagnostic Tool but Not of Prognostic Value

Background

Adrenocortical carcinoma (ACC) is a rare cancer for which little level evidence exists to guide management. ¹⁸F-FDG PET (¹⁸F-fluorodeoxyglucose positron emission tomography) is an increasingly used diagnostic tool in patients with suspicious or indeterminate adrenal tumors. In some other solid tumors, ¹⁸F-FDG PET may offer prognostic information that can guide optimal patient treatment. The aim of the present study was to evaluate whether preoperative ¹⁸F-FDG PET based on SUVs assessments has a prognostic value in ACC patients.

Methods

A retrospective analysis was performed in patients who underwent ¹⁸F-FDG PET/CT for the evaluation of ACC. Inclusion criteria were an unequivocal diagnosis of ACC; all data from primary diagnosis available; ¹⁸F-FDG PET/CT performed prior to surgery or other treatment of the primary tumor; a minimum of 6-months follow-up for surviving patients. All ¹⁸F-FDG PET/CT procedures were reinterpreted in a blind fashion.

Results

Thirty-seven patients (23 without metastasis [M0], 14 with metastasis [M1]) fulfilled the study criteria. Median uptake values were tumor standardized uptake values (SUV)_max = 11 (range: 3–56) and a tumor/liver SUV_max ratio = 4.2 (range: 1.3–15). Median follow-up was 20 months. Although classic risk factors (tumoral stage, Weiss score) were associated with poor outcome, there was no correlation between primary tumor FDG uptake with overall survival (OS) and disease free survival (DFS) in M0 patients and with overall survival in M1 patients. ¹⁸F-FDG uptake correlated inconsistently with sinister histological features, such as atypical mitoses or necrosis.

Conclusions

At initial staging, primary tumor FDG uptake in ACC patients does not correlate with OS and DFS at 2 years. Patient prognosis and treatment strategy should not be based on uptake values.