Abstract
AimsRadiotherapy with concurrent 5-fluorouracil/mitomycin-C based chemotherapy has been established as definitive standard therapy approach for anal cancer. Intensity Modulated Radiotherapy (IMRT) leads to a precise treatment of the tumor, allowing dose escalation on Gross Tumor Volume (GTV), with a surrounding healthy tissues sparing. Our study assessed the impact of 18-Fluorodeoxyglucose positron emission tomography (18FDG-PET/CT) on the radiotherapy contouring process and its contribution to lymphatic spread detection, resulting to a personalization of Clinical Target Volume (CTV) and dose prescription.MethodsThirty-seven patients, with histologically proven squamous cell carcinoma of the anal canal (SCCAC) were analyzed. All patients were evaluated with history and physical examination, trans-anal endoscopic ultrasound, pelvis magnetic resonance imaging (MRI), computed tomography (CT) scans of the chest, abdomen and pelvis and planning 18FDG-PET/CT. The GTV and CTV were drawn on CT, MRI and 18FDG-PET/CT fused images.ResultsThirty-four (91%) out of 37 patients presented lymph nodes involvement, in one or more areas, detected on 18FDG-PET/CT and/or MRI. The 18FDG-PET/CT showed positive lymph nodes not detected on MRI imaging (PET+, MRI−) in 14/37 patients (38%). In 14 cases, 18FDG-PET/CT allowed to a dose escalation in the involved nodes. The 18FDG-PET/CT fused images led to change the stage in 5/37(14%) cases: four cases from N0 to N1 (inguinal lymph nodes) and in one case from M0 to M1 (common iliac lymph nodes).ConclusionsThe 18FDG-PET/CT has a potentially relevant impact in staging and target volume delineation/definition in patients affected by anal cancer. In our experience, clinical stage variation occurred in 14% of cases. More investigations are needed to define the role of 18FDG-PET/CT in the target volume delineation of anal cancer.
Highlights
Anal cancer is a rare disease accounting for 1–2% of digestive tract tumor in Europe and it is strongly related to HPV infection in as many as 90% of cases
From the total of anal cancer patients treated in our Institute, we selected patients with squamous cell carcinoma of the anal canal (SCCAC) that performed, for clinical staging, trans-anal endoscopic ultrasound, pelvis magnetic resonance imaging (MRI), total body computed tomography (CT) scans with contrast enhancement and planning 18FDG/PET-CT
In 34/37 (91%) patients there was lymph nodal involvement detected on 18FDG-PET/CT and/or MRI
Summary
Anal cancer is a rare disease accounting for 1–2% of digestive tract tumor in Europe and it is strongly related to HPV infection in as many as 90% of cases.At diagnosis, 50% of anal cancer results confined to the primary site, 30% presents regional lymph nodes (LN) involvement while distant metastases are reelevated in less than 10% of cases [1, 2].In locally advanced stage, the standard of care is represented by concurrent radio-chemotherapy with 5-fluorouracil and mitomycin C. Anal cancer is a rare disease accounting for 1–2% of digestive tract tumor in Europe and it is strongly related to HPV infection in as many as 90% of cases. 50% of anal cancer results confined to the primary site, 30% presents regional lymph nodes (LN) involvement while distant metastases are reelevated in less than 10% of cases [1, 2]. Magnetic resonance imaging (MRI) represents the gold standard in detecting tumor extension and the involvement of adjacent structures such as muscles and soft tissues. 18-Fluorodeoxyglucose (18FDG) positron emission tomography (PET/CT) is having an increasing role in staging and treatment planning of anal carcinoma, because of the high 18FDG-PET/CT avidity of this tumor [4,5,6]
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