EDITORIAL Portrait of a polyp: the CTC dilemma Franco Iafrate, 1 Cesare Hassan, 2 Perry J. Pickhardt, 3 Alessandro Pichi, 1 Andrea Stagnitti, 1 Angelo Zullo, 2 Emilio Di Giulio, 4 Andrea Laghi 5 1 Department of Radiological Sciences, ‘‘Sapienza’’ University of Rome, Viale Regina Elena 324, Rome 00161, Italy 2 Gastroenterology and Digestive Endoscopy Unit, Nuovo Regina Margherita Hospital, Rome, Italy 3 Department of Radiology, University of Wisconsin Medical School, Madison, WI, USA 4 Digestive and Liver Disease Unit, Sant’Andrea Hospital, ‘‘Sapienza’’ University of Rome, Rome, Italy 5 Department of Radiological Sciences, ‘‘Sapienza’’ University of Rome Polo Pontino, Latina, Italy Colorectal cancer (CRC) is a major cause of morbidity and mortality in western societies, in which its therapeutic cost also represents a substantial economic burden [1]. According to the adenoma–carcinoma sequence, the vast majority of CRC arise from benign polyps over a very long period of time [2], so that screening based on polyp detection has been universally accepted [3]. Among the available options, CT colonography (CTC) has shown a good accuracy for large polyps and carcinomas [4–6], and it has been included among the recommended options for CRC screening in average-risk people [7]. CTC offers the possibility to select for endoscopic polypectomy only those patients with polyps at higher risk of progression into cancer, which could be regarded as an advantage due to the discomfort and the complication risk associated with operative colonoscopy [8, 9]. Such policy appears similar to the dimension threshold—usually a polyp ‡5 mm— used to recommend a colonoscopy after a positive screening flexible sigmoidoscopy, in order to avoid too many false-positive examinations [10]. In detail, it has been proposed that only polyps larger than 10 mm at CTC should trigger an immediate polypectomy, while smaller polyps could be alternatively either ignored—especially if £5 mm—or followed up [11, 12]. However, there is still some controversy on the validity of this approach, since it leaves some patients with the potential risk of already harboring or developing a malignant lesion in a relatively short period of time [13]. Moreover, the medical choice of not reporting a potentially clinically relevant lesion raises some concern on the ethical aspects and the associated jeopardy of legal litigations. Although the natural history of the adenoma–carci- noma sequence is still incompletely understood, several articles have addressed the prevalence of the neoplastic lesions and the associated risk of unfavorable histologi- cal features according to polyp size. The aim of this review is to match such information with the available data on CTC accuracy, in order to clarify the clinical implications of the different managements which may be proposed for polyps <10 mm. Advanced polyps The wide discrepancy between the extremely high prev- alence of polyps, up to 50%–60% of the population older than 50 years, and the relatively low prevalence of CRC, 0.1%–1%, implies that only a tiny fraction of all the adenomas eventually progress to cancer. Since the early 1970s, an intimate relationship between the size of the polyps and the presence of unfavorable histology has been clearly shown [14–17]. In particular, high-grade dysplasia (HGD) or already developed malignancy appeared to be much more prevalent among ‡10 mm lesions than smaller lesions (Table 1), unveiling a major role for this threshold in the clinical practice. This evi- dence has been dynamically confirmed by a pre-colono- scopic radiological study in which the cumulative CRC risk in patients with a polyp ‡10 mm appeared to be 24% at 20 years, being several fold higher than that expected in the general population—less than 3%—according to SEER data [18, 19]. More recently, Vogelstein has demonstrated that polyps larger than 10 mm are much more likely to accumulate oncogenic mutations than small lesions, offering a genetic rationale for their aggressive behavior [20]. Correspondence to: Franco Iafrate; email: francoiafrate@gmail.com ª Springer Science+Business Media, LLC 2008 Published online: 25 December 2008 Abdominal Imaging Abdom Imaging (2010) 35:49–54 DOI: 10.1007/s00261-008-9494-3