Incidental detection of colorectal malignancies using FDG PET-CT

Area of Science:

• Oncology
• Radiology
• Gastroenterology

Background:

• Whole-body 18FDG-PET/CT is increasingly used for staging and monitoring various cancers.
• Incidental findings of colorectal malignancies during these scans are not well-characterized.
• Early detection of colorectal cancer improves patient outcomes.

Purpose of the Study:

• To determine the detection rate of incidental colorectal malignancies and premalignant lesions using 18FDG-PET/CT.
• To evaluate the incidence of adenocarcinoma and its stage at diagnosis.
• To compare these findings with existing literature.

Main Methods:

• Retrospective review of 800 consecutive patients undergoing 18FDG-PET/CT from January to August 2009.
• Analysis of radiologic reports for focal colonic FDG uptake.
• Audit of scans with focal uptake, followed by review of colonoscopic and histologic records for patients undergoing further investigation.

Main Results:

• Out of 643 included patients, 7.5% (48 patients) showed focal colonic FDG uptake.
• 2.2% of all patients (14/643) had biopsies positive for dysplasia.
• 1.2% of all patients (8/643) were diagnosed with adenocarcinoma, with 50% at TNM stage 1 or 2.

Conclusions:

• 18FDG-PET/CT can incidentally detect colorectal malignant and premalignant lesions at a significant rate (2.2%).
• The identified rate of adenocarcinoma (1.2%) is higher than previously reported, suggesting PET/CT's potential in early colorectal cancer detection.
• Further investigation of incidental colonic uptake on PET/CT is warranted.