Impact of PET/CT on initial staging, restaging and treatment management of anal cancer: a clinical case with literature review.

Distant extrapelvic metastases appear in approximately in 10% of the patients with squamous cell anal cancer (SCAC) and survival depends on the treatment strategy. Exact staging leads to optimal planning of multimodality therapy and the adequate evaluation of treatment response can improve the prognosis of the disease. Diagnosis and staging of SCAC are commonly performed using contrast-enhanced computerized tomography(CT) and interpretation of the findings for tumor biological behavior. F18-fluoro-2 deoxy-D glucose positron emission tomography((18)F-FDG PET) reveals aspects of tumor function and allows metabolic measurements. Combined PET/CT scans permit exact localization with anatomical criteria of the hypermetabolic (18)F-FDG avid malignant lesions. We present a patient with SCAC in whom, according to PET/CT findings, the initial stage was changed from II (T2N0M0) to III A (T2N2M0). Radiation therapy (RT) and chemotherapy achieved a good therapeutic response but early follow up revealed new paraaortic lymph node (LN) metastases, as well as an uncommon left supraclavicular LN metastasis from the same primary carcinoma. The disease was restaged as stage IV (T2N2M1) and radiation therapy was substituted by chemotherapy.