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

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 4months 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.