Relationship between Preoperative ¹⁸F-Fluorodeoxyglucose Uptake and Epidermal Growth Factor Receptor Status in Primary Colorectal Cancer

Abstract

Purpose: Both ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake and epidermal growth factor receptor (EGFR) status are prognostic variables of colorectal cancer (CRC). The aim of this study was to investigate a possible association between ¹⁸F-FDG uptake on preoperative positron emission tomography/computed tomography (PET/CT) and EGFR status in primary CRC.

Materials and methods: Records of 132 patients (66 men and 66 women; mean age=67.1±11.1 years) who underwent ¹⁸F-FDG PET/CT for CRC staging and subsequent bowel resection were reviewed. In primary lesions, ¹⁸F-FDG uptake was semiquantitatively evaluated in terms of maximum standardized uptake value (SUVmax), and EGFR status was determined by immunohistochemistry. Associations of clinicopathological parameters and EGFR status were analyzed by Pearson's chi-square test, multiple logistic regression, and receiver operating characteristic curves.

Results: Eighty-six patients (65.2%) showed EGFR expression. SUVmax was significantly lower in EGFR-negative tumors than in EGFR-expressing tumors (10.0±4.2 vs. 12.1±2.1; p=0.012). It was the only significant parameter correlated with EGFR expression (odds ratio=2.457; relative risk=2.013; p=0.038). At the SUVmax threshold of 7.5, the sensitivity and specificity for predicting EGFR expression were 84.9% and 40.4%, respectively (area under the curve=0.624; p=0.019).

Conclusion: Preoperative ¹⁸F-FDG uptake is slightly correlated with EGFR status in primary CRC. Preoperative SUVmax of ¹⁸F-FDG may have a limited role in predicting EGFR expression in such tumors because of its poor specificity.

Keywords: Colorectal cancer; epidermal growth factor receptor; ¹⁸F-fluorodeoxyglucose.

Fig. 1. Relationships of SUV_max, tumor size, and CEA level in primary CRC. (A) SUV_max showed a significant positive linear correlation with tumor size (r=0.293; p=0.001). (B) Tumor size and CEA level showed a significant positive linear correlation (r=0.253; p=0.003). (C) No correlation was noted between CEA level and SUV_max (r=0.151; p=0.083). SUV_max, maximum standardized uptake value; CEA, carcinoembryonic antigen; CRC, colorectal cancer.

Fig. 2. Relationship of SUV_max and EGFR status in primary CRC. EGFR-expressing tumors had higher SUV_max than EGFR-negative tumors. SUV_max, maximum standardized uptake value; EGFR, epidermal growth factor receptor; CRC, colorectal cancer.

Fig. 3. ROC curves of SUV_max, tumor size, and CEA level for predicting EGFR expression in primary CRC. SUV_max: AUC=0.624, p=0.019; tumor size: AUC=0.506, p=0.909; CEA level: AUC=0.445, p=0.296. ROC, receiver operating characteristic; SUV_max, maximum standardized uptake value; CEA, carcinoembryonic antigen; EGFR, epidermal growth factor receptor; CRC, colorectal cancer; AUC, area under the curve.