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Correlation Between PET/CT Parameters and KRAS Expression in Colorectal Cancer

Chen, Shang-Wen MD*†‡; Chiang, Hua-Che MD§; Chen, William Tzu-Liang MD†§; Hsieh, Te-Chun MD∥¶; Yen, Kuo-Yang MD∥¶; Chiang, Shu-Fen MD**; Kao, Chia-Hung MD†∥

doi: 10.1097/RLU.0000000000000481
Original Articles

Purpose The objective of this study was to correlate the association between mutated KRAS and wild-type colorectal cancer (CRC) by using various 18F-FDG PET–related parameters.

Methods One hundred twenty-one CRC patients who had undergone preoperative PET/CT were included in this study. Several PET/CT-related parameters, including SUVmax and various thresholds of metabolic tumor volume, total lesion glycolysis, and PET/CT-based tumor width, were measured. Tumor- and PET/CT-related parameters were correlated with genomic expression between KRAS mutant and wild-type groups, using a Mann-Whitney U test and logistic regression analysis.

Results Colorectal cancer tumors with a mutated KRAS exhibited higher SUVmax and an increased accumulation of FDG among several threshold methods. Multivariate analysis showed that SUVmax and using a 40% threshold level for maximal uptake of TW (TW40%) were the 2 predictors of KRAS mutations. The odds ratio was 1.23 for SUVmax (P = 0.02; 95% confidence interval, 1.01–1.52) and 1.15 for TW40% (P = 0.02; 95% confidence interval, 1.02–1.30). The accuracy of SUVmax for predicting mutated KRAS was higher in patients with colon or sigmoid colon cancers, whereas it was TW40% in those with rectal cancers.

Conclusions SUVmax and TW40% were associated in CRC with KRAS mutations. PET/CT parameters can supplement genomic analysis to determine KRAS expression in CRC.

Supplemental digital content is available in the text.

From the *Department of Radiation Oncology, China Medical University Hospital; and †Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University, Taichung; ‡School of Medicine, Taipei Medical University, Taipei; and §Departments of Surgery and ∥Department of Nuclear Medicine and PET Center, China Medical University Hospital; ¶Department of Biomedical Imaging and Radiological Science, China Medical University; and **Cancer Center, China Medical University Hospital, Taichung, Taiwan.

Received for publication December 2, 2013; revision accepted April 2, 2014.

Conception and design: S.-W.C., H.-C.C., W.T.-L.C., C.-H.K.; administrative support: T.-C.H., K.-Y.Y., T.-W.C., C.S.-F.; collection and assembly of data: all authors; data analysis and interpretation: S.-W.C., C.-H.K.; manuscript writing: all authors; final approval of manuscript: all authors.

Conflicts of interest and sources of funding: The authors received study grants for projects DMR-102-023 and DMR-103-018 conducted in their hospital, issued by the Taiwan Ministry of Health and Welfare Clinical Trial and Research Center for Excellence (DOH102-TD-B-111-004) and Taiwan Ministry of Health and Welfare Cancer Research Center for Excellence (MOHW103-TD-B-111-03).

Reprints: Chia-Hung Kao, MD, Department of Nuclear Medicine and PET Center, China Medical University Hospital, No. 2, Yur-Der Rd, Taichung 404, Taiwan. E-mail: d10040@mail.cmuh.org.tw.

Supplemental digital content is available for this article. Direct URL citation appears in the printed text and is provided in the HTML and PDF versions of this article on the journal’s Web site (www.nuclearmed.com).

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