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Relationship Between 18F-FDG PET/CT Scans and KRAS Mutations in Metastatic Colorectal Cancer
Kenji Kawada1, Kosuke Toda2, Yuji Nakamoto3
1Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan kkawada@kuhp.kyoto-u.ac.jp.
Unlabelled:
Several studies have shown that KRAS mutations in colorectal cancer (CRC) result in the lack of response to anti-epidermal growth factor receptor-based therapy; thus, KRAS mutational testing has been incorporated into routine clinical practice. However, 1 limitation of this test is the heterogeneity of KRAS status, which can be either intratumoral heterogeneity within an individual primary CRC or discordant KRAS status between a primary CRC and its corresponding metastases. We previously reported that (18)F-FDG accumulation was significantly higher in primary CRCs with mutated KRAS than in those with wild-type KRAS. However, the clinical utility of the previous report has been limited because endoscopic biopsy for testing KRAS status is safe and feasible only in primary CRC. The purpose of this study was to investigate whether KRAS status is associated with (18)F-FDG accumulation in metastatic CRC and whether (18)F-FDG PET/CT scans can be used to predict the KRAS status of metastatic CRC.
Methods:
A retrospective analysis was performed on 55 metastatic CRC tumors that were identified by (18)F-FDG PET/CT before surgical resection. Maximum standardized uptake value (SUVmax) of the respective metastatic tumor was calculated from (18)F-FDG accumulation.
Results:
From the analysis with the 55 tumors, no significant correlation was found between SUVmax and KRAS status. We next analyzed only tumors larger than 10 mm to minimize the bias of partial-volume effect and found that SUVmax was significantly higher in the KRAS-mutated group than in the wild-type group (8.3 ± 4.1 vs. 5.7 ± 2.4, respectively; P = 0.03). Multivariate analysis indicated that SUVmax remained significantly associated with KRAS mutations (P = 0.04). KRAS status could be predicted with an accuracy of 71.4% when an SUVmax cutoff value of 6.0 was used.
Conclusion:
(18)F-FDG accumulation into metastatic CRC was associated with KRAS status. (18)F-FDG PET/CT scans may be useful for predicting the KRAS status of metastatic CRC and help in determining the therapeutic strategies against metastatic CRC.
Insights
Positron emission tomography (PET) scans using 18F-FDG may predict KRAS status in metastatic colorectal cancer (CRC). Higher 18F-FDG uptake in larger tumors suggests a potential non-invasive method for guiding treatment strategies.
Area of Science:
- Oncology
- Nuclear Medicine
- Molecular Diagnostics
Background:
- KRAS mutations in colorectal cancer (CRC) predict treatment response but testing faces limitations due to tumor heterogeneity.
- Previous research indicated higher 18F-FDG uptake in primary KRAS-mutated CRCs, but clinical utility was limited by biopsy accessibility in metastatic disease.
Purpose of the Study:
- To investigate the association between 18F-FDG accumulation and KRAS status in metastatic CRC.
- To determine if 18F-FDG PET/CT can predict KRAS mutational status in metastatic CRC non-invasively.
Main Methods:
- Retrospective analysis of 55 metastatic CRC tumors assessed by 18F-FDG PET/CT prior to resection.
- Calculation of maximum standardized uptake value (SUVmax) from 18F-FDG accumulation in tumors.
- Analysis considering tumor size (>10 mm) to mitigate partial-volume effects.
Main Results:
- No significant correlation between SUVmax and KRAS status was found in all analyzed tumors.
- In tumors >10 mm, SUVmax was significantly higher in KRAS-mutated CRC compared to wild-type (8.3 vs. 5.7, P=0.03).
- Multivariate analysis confirmed SUVmax association with KRAS mutations (P=0.04), achieving 71.4% prediction accuracy with an SUVmax cutoff of 6.0.
Conclusions:
- 18F-FDG accumulation in metastatic CRC is associated with KRAS mutational status.
- 18F-FDG PET/CT shows potential for predicting KRAS status in metastatic CRC.
- This imaging technique may aid in selecting appropriate therapeutic strategies for metastatic CRC patients.
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