Anal cancer maximum F-18 fluorodeoxyglucose uptake on positron emission tomography is correlated with prognosis

Abstract

Purpose To evaluate anal cancer uptake of F-18 fluorodeoxyglucose (FDG) measured as the maximum standardized uptake value (SUV max) by positron emission tomography (PET) and its correlation with prognostic factors. Patients and methods The study population consisted of 77 patients with stages 0–IIIB anal cancer who underwent pre-treatment FDG-PET. Tumor histology included 65 squamous cell, 11 basaloid, and 1 small cell cancers. SUV max and sites of lymph node metastasis were recorded. We analyzed the association between SUV max and prognostic factors. Results The mean SUV max was 10.0 (range 1.0–43.1). The stage distribution included: 2 stage 0, 7 stage I, 49 stage II, 10 stage IIIA, 9 stage IIIB. SUV max and clinical tumor size were not associated ( R 2 = 0.338). Histology did not significantly influence SUV max (mean SUV max 10.0 for squamous versus 9.90 for basaloid). Higher SUV max was associated with an increased risk of nodal metastasis at diagnosis ( p < 0.0001). Higher SUV max was associated with worse disease-free survival ( p = 0.05). Patients with high anal tumor SUV max at diagnosis were at an increased risk of persistent or recurrent disease on post-therapy FDG-PET performed less than 4 months after completing therapy ( p = 0.0402). Conclusions SUV max is a valuable biomarker of anal cancer prognosis, predicting increased risk of lymph node metastasis and worse disease-free survival.