Accuracy of PET/CT for the Detection of Synchronous Malignant Lesions in Patients With Endoscopically Obstructive Colorectal Cancer
Cemil Burak Kulle, Mehmet Iskender Yıldırım, Halil Alper Bozkurt, Emine Göknur Işık, Melek Büyük, Neslihan Berker, İlker Özgür, Mehmet Türker Bulut, Metin Keskin, Adem BayraktarBackground:
This study aimed to assess the diagnostic performance of positron emission tomography/computed tomography (PET/CT) in detecting synchronous malignant lesions in the proximal colon in endoscopically obstructive left-sided colorectal cancer.
Materials and Methods:
All patients with a biopsy-proven left-sided endoscopically obstructive colorectal cancer who had a preoperative PET/CT scan and a postoperative total colonoscopy within 6 months after the index surgery between January 2015 and July 2024 at a comprehensive cancer center were enrolled into the study. The synchronous malignant lesions on PET/CT were confirmed with the pathologic examination of the subtotal/total colectomy specimen and postoperative total colonoscopy. The primary endpoint was to evaluate the diagnostic performance of PET/CT in detecting synchronous malignant lesions, and the second endpoint was to determine the ability of PET/CT to distinguish malignant lesions from advanced adenomas.
Results:
Out of 90 patients, 50 (55.6%) were male with a mean age of 62.46±10.81 years. The obstructing malignant lesions detected on colonoscopy were located in the rectum, n=8 (8.9%), rectosigmoid junction, n=29 (32.2%), sigmoid colon, n=31 (34.4%), descending colon, n=16 (17.8%), and distal part of the transverse colon, n=6 (6.7%). Nine areas of abnormal fluorodeoxyglucose (FDG) uptake on PET/CT in the proximal part of the colon with a mean SUVmax value of 19.23 (range: 6.4-42) were identified in 6 patients. Four patients with synchronous lesions on PET/CT underwent a total colectomy. Two patients with synchronous lesions on PET/CT were treated with segmental resection with subsequent postoperative endoscopic submucosal dissection (ESD) for the synchronous lesion. The detection rate of PET/CT for synchronous malignant lesions was 4.4% (n=4) with a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 100%, 94.4%, 44.4%, 100%, and 94.6%, respectively.
Conclusions:
PET/CT demonstrated a high sensitivity and a high negative predictive value in detecting synchronous malignant lesions located in the proximal colon distal to the obstructing left-sided colorectal cancer. As a result, patients underwent a single-stage surgery and were spared from an unnecessary second surgical intervention.