Anal cancer FDG-PET standard uptake value: correlation with tumor characteristics, treatment response and survival

The present work studies the correlation of (18) F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) standardized uptake value (SUV) with tumor characteristics, clinical response and prognosis in a series of anal canal cancer patients treated with chemo-radiotherapy.

Fifty-five patients were included in the present analysis. PET maximum SUV (SUVmax) of primary tumor was calculated for each patient. The correlation with clinical parameters, tumor response and survival data were analyzed.

SUVmax significantly correlated with T-stage (p = 0.01) and histology (p = 0.03). Median SUVmax was higher for lesions with partial response (PR, 21/55, 38%) than for lesions with complete response (CR, 34/55, 62%) but without statistical significance (p = 0.17). The actuarial disease-free survival (DFS) and overall survival (OS) rates were 53.0 and 77.8% at 2 years and 41.3 and 58.6% at 5 years, respectively. Median SUVmax did not statistically correlate with clinical response or survival. CR and T1-T2 stage were statistically significant prognostic factors for disease-free survival (p < 0.0001 and p = 0.02, respectively) and CR was significant also for overall survival (p < 0.0001).

Our data suggest that pre-treatment FDG-PET/CT SUVmax cannot directly predict tumor response and survival, but it is strongly associated with tumor characteristics such as primary tumor stage and histology, being the first one of the most important and validated prognostic factors for anal cancer.