The prognostic role of FDG PET/CT before combined radio-chemotherapy in anal cancer patients
We assessed the prognostic value of several FDG PET/CT parameters, measured within the primary tumor and the involved lymph nodes, before definitive radio-chemotherapy (RCT) in anal cancer patients.
Anal cancer patients with positive baseline FDG PET/CT who underwent definitive RCT from May 2011 to February 2018 were retrospectively assessed. Primary tumour (T)-SUVmax, T-SUVpeak, T-SUVmean, T-MTV, T-TLG, whole-body (WB) MTV, and WB-TLG were measured. Kaplan–Meier curves, Cox-regression analysis, and logistic regression machine-learning technique were used to test for associations between clinical data, metabolic parameters, and outcomes as overall survival (OS), disease-specific survival (DSS), metastatic-free survival (MFS), disease-free survival (DFS), local relapse-free survival (LRFS), and colostomy-free survival (CFS).
Fifty-nine patients were included in the study. Median follow-up was 28 months. Higher pre-treatment WB-MTV, T-TLG, and WB-TLG were associated with worse OS (p = 0.025, 0.021, and 0.02, respectively). PET parameters resulted also statistically significant for DSS, DFS, and CFS (p = 0.032, 0.043, 9 × 10−4 for WB-TLG). Cox analysis showed that PET parameters are significant predictors of OS, DSS, DFS, CFS, and LRFS. On multivariate analysis, age, stage, T-SUVpeak, WB-MTV, and T-TLG resulted significantly related to OS. A further stratification for patients with advanced stage (cT3-4 any N or any cT, N + ) showed that MTV and TLG, measured within the primary tumor and the involved nodes, are significantly higher in patients with a worse prognosis. In this subgroup, cut-off values of T- and WB-TLG as well as T- and WB-MTV showed a statistically significant correlation with clinical outcomes.
Pre-treatment metabolic parameters measured within the primary tumor and the involved nodes may represent additional new biomarkers for estimating prognosis in anal cancer patients, especially in advanced stage patients.
KeywordsPET FDG Anal cancer MTV TLG Prognosis Personalized medicine
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