Abstract
BackgroundFDG-PET/CT imaging has an emerging role in staging and treatment planning of various tumor locations and a number of literature studies show that also the carcinoma of the anal canal may benefit from this diagnostic approach. We analyzed the potential impact of FDG-PET/CT in stage definition and target volume delineation of patients affected by carcinoma of the anal canal and candidates for curative radiotherapy.MethodsTwenty seven patients with biopsy proven anal carcinoma were enrolled. Pathology was squamous cell carcinoma in 20 cases, cloacogenic carcinoma in 3, adenocarcinoma in 2, and basal cell carcinoma in 2. Simulation was performed by PET/CT imaging with patient in treatment position. Gross Tumor Volume (GTV) and Clinical Target Volume (CTV) were drawn on CT and on PET/CT fused images. PET-GTV and PET-CTV were respectively compared to CT-GTV and CT-CTV by Wilcoxon rank test for paired data.ResultsPET/CT fused images led to change the stage in 5/27 cases (18.5%): 3 cases from N0 to N2 and 2 from M0 to M1 leading to change the treatment intent from curative to palliative in a case.Based on PET/CT imaging, GTV and CTV contours changed in 15/27 (55.6%) and in 10/27 cases (37.0%) respectively. PET-GTV and PET-CTV resulted significantly smaller than CT-GTV (p = 1.2 × 10-4) and CT-CTV (p = 2.9 × 10-4). PET/CT-GTV and PET/CT-CTV, that were used for clinical purposes, were significantly greater than CT-GTV (p = 6 × 10-5) and CT-CTV (p = 6 × 10-5).ConclusionsFDG-PET/CT has a potential relevant impact in staging and target volume delineation of the carcinoma of the anal canal. Clinical stage variation occurred in 18.5% of cases with change of treatment intent in 3.7%. The GTV and the CTV changed in shape and in size based on PET/CT imaging.
Highlights
(18)F-fluorodeoxyglucose positron emission tomography fused with computed tomography (FDG-PET/CT) imaging has an emerging role in staging and treatment planning of various tumor locations and a number of literature studies show that the carcinoma of the anal canal may benefit from this diagnostic approach [6,9,10,11,12,13]
The present prospective study aims to analyze the potential impact of FDG-PET/CT in staging and target volume delineation of patients affected by carcinoma of the anal canal and candidates for curative radiotherapy combined with concomitant chemotherapy
The case with multiple lesions in the liver was treated with palliative radiotherapy followed by chemotherapy whereas the other case presenting with a single FDG uptake lesion received combined radio-chemotherapy as the other cases treated by curative intent
Summary
FDG-PET/CT imaging has an emerging role in staging and treatment planning of various tumor locations and a number of literature studies show that the carcinoma of the anal canal may benefit from this diagnostic approach. We analyzed the potential impact of FDG-PET/CT in stage definition and target volume delineation of patients affected by carcinoma of the anal canal and candidates for curative radiotherapy. The treatment approach moved from an extensive surgical approach consisting of abdominal-perineal resection to a conservative chemo-radiation regimen proposed firstly by Nigro et al who reported high response and survival rates after a combination of radiotherapy and chemotherapy [3] The efficacy of such an approach was confirmed by phase III (18)F-fluorodeoxyglucose positron emission tomography fused with computed tomography (FDG-PET/CT) imaging has an emerging role in staging and treatment planning of various tumor locations and a number of literature studies show that the carcinoma of the anal canal may benefit from this diagnostic approach [6,9,10,11,12,13].
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