Optimizing the role of FDG PET-CT for potentially operable metastatic colorectal cancer

A novel diagnostic model for differentiation of lung metastasis from primary lung cancer in patients with colorectal cancer

Objective

This study aimed to evaluate the ¹⁸F-FDG PET/CT in differentiating lung metastasis(LM) from primary lung cancer(LC) in patients with colorectal cancer (CRC).

Methods

A total of 120 CRC patients (80 male, 40 female) who underwent ¹⁸F-FDG PET/CT were included. The diagnosis of primary lung cancer or lung metastasis was based on histopathology The patients were divided into a training cohort and a validation cohort randomized 1:1. Independent risk factors were extracted through the clinical information and ¹⁸F-FDG PET/CT imaging characteristics of patients in the validation cohort, and then a diagnostic model was constructed and a nomograms was made. ROC curve, calibration curve, cutoff, sensitivity, specificity, and accuracy were used to evaluate the prediction performance of the diagnostic model.

Results

One hundred and twenty Indeterminate lung lesions (ILLs) (77 lung metastasis, 43 primary lung cancer) were analyzed. No significant difference in clinical characteristics and imaging features between the training and the validation cohorts (P > 0. 05). Using uni-/multivariate analysis, pleural tags and contour were identified as independent predictors. These independent predictors were used to establish a diagnostic model with areas under the receiver operating characteristic curves (AUCs) of 0.92 and 0.89 in the primary and validation cohorts, respectively. The accuracy rate of the diagnostic model for differentiating LM from LC were higher than that of subjective diagnosis (P < 0.05).

Conclusions

Pleural tags and contour were identified as independent predictors. The diagnostic model of ILLs in patients with CRC could help differentiate between LM and LC.

Is It Time to Introduce PET/CT in Colon Cancer Guidelines?

International colon cancer guidelines suggest F-FDG PET/CT in a few circumstances: (1) at disease presentation in case of suspected or proven metastatic synchronous adenocarcinoma; (2) in the workup of recurrent colon cancer with metachronous metastases documented by CT, MRI, or biopsy and in case of serial CEA elevation with negative colonoscopy and negative CT; and (3) in case of contraindication to iodine- and gadolinium-based contrast agents. However, review of the literature has shown that PET/CT can also be used in other scenarios with significant levels of diagnostic advantage. This review aims to emphasize differences between guidelines and scientific literature for the use of PET/CT in colon cancer.

Lung metastasectomy after colorectal cancer: prognostic impact of resection margin on long term survival, a retrospective cohort study

BACKGROUND

Pulmonary metastasectomy is considered a potentially curative treatment for selected patients with metastatic colorectal cancer (CRC). Several prognostic factors have been analysed, but to date, it is still not well defined which is the optimal resection margin during lung metastasectomy (LM). This study analyses the long-term results and prognostic factors after LM in CRC patients with particular attention to the resection margins. Primary endpoint of this study is to assess the correlation between resection margins and long-term outcomes.

METHODS

Observational cohort study on all proven cases of CRC lung metastases (2000-2016) resected with curative intent in a single centre.

RESULTS

The series included 210 consecutive patients (M/F 133/77) with a mean age of 65.4 (± 9.96) years, 75% (159/210) of them with a solitary metastasis. Mean size of metastasis was 2.57 cm (± 1.45). One hundred sixty-eight patients underwent wedge resections (80%) and lymphadenectomy was carried out in 90 cases (42.9%). With a mean follow-up of 56 months (range 5-192), we observed a 1-, 3- and 5-year overall survival (OS) of 95%, 74% and 54%, respectively. The patients were divided into three groups according to the resection margin distance from the tumour: (a) ≥ 2 cm (145 cases); (b) < 2, ≥ 1 cm (37 cases); and (c) < 1 cm (12 cases). The OS was significantly different between the three groups (p = 0,020); univariate and multivariate analyses showed that a narrow resection margin was an independent prognostic factor of worse survival (p = 0.006 and HR 3.4 p = 0.009).

CONCLUSIONS

Long-term survival of patients after LM is strongly associated with a greater distance between the lesion and the resection margin.

Noninvasive Biomarkers of Colorectal Cancer: Role in Diagnosis and Personalised Treatment Perspectives

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths worldwide. It has been estimated that more than one-third of patients are diagnosed when CRC has already spread to the lymph nodes. One out of five patients is diagnosed with metastatic CRC. The stage of diagnosis influences treatment outcome and survival. Notwithstanding the recent advances in multidisciplinary management and treatment of CRC, patients are still reluctant to undergo screening tests because of the associated invasiveness and discomfort (e.g., colonoscopy with biopsies). Moreover, the serological markers currently used for diagnosis are not reliable and, even if they were useful to detect disease recurrence after treatment, they are not always detected in patients with CRC (e.g., CEA). Recently, translational research in CRC has produced a wide spectrum of potential biomarkers that could be useful for diagnosis, treatment, and follow-up of these patients. The aim of this review is to provide an overview of the newer noninvasive or minimally invasive biomarkers of CRC. Here, we discuss imaging and biomolecular diagnostics ranging from their potential usefulness to obtain early and less-invasive diagnosis to their potential implementation in the development of a bespoke treatment of CRC.

Advanced Imaging Techniques in Evaluation of Colorectal Cancer

Imaging techniques are clinical decision-making tools in the evaluation of patients with colorectal cancer (CRC). The aim of this article is to discuss the potential of recent advances in imaging for diagnosis, prognosis, therapy planning, and assessment of response to treatment of CRC. Recent developments and new clinical applications of conventional imaging techniques such as virtual colonoscopy, dual-energy spectral computed tomography, elastography, advanced computing techniques (including volumetric rendering techniques and machine learning), magnetic resonance (MR) imaging-based magnetization transfer, and new liver imaging techniques, which may offer additional clinical information in patients with CRC, are summarized. In addition, the clinical value of functional and molecular imaging techniques such as diffusion-weighted MR imaging, dynamic contrast material-enhanced imaging, blood oxygen level-dependent imaging, lymphography with contrast agents, positron emission tomography with different radiotracers, and MR spectroscopy is reviewed, and the advantages and disadvantages of these modalities are evaluated. Finally, the future role of imaging-based analysis of tumor heterogeneity and multiparametric imaging, the development of radiomics and radiogenomics, and future challenges for imaging of patients with CRC are discussed. Online supplemental material is available for this article. ^©RSNA, 2018.

Correlation between KRAS mutation and 18F-FDG uptake in stage IV colorectal cancer

PURPOSE

The purpose of this study is to evaluate the correlation between KRAS mutation, ¹⁸F-FDG uptake, and metastatic pattern in advanced stage colorectal cancer (CRC) patients.

METHODS

Medical records of stage IV CRC patients who underwent ¹⁸F-FDG PET/CT for staging and KRAS mutation analysis were selected. On PET scans, a volume of interest (VOI) was drawn on the primary lesion. ¹⁸F-FDG indices (SUVmax, SUVmean, MTV, TLG) of the primary lesions were obtained and correlated with KRAS mutation of the primary lesion. Also, metastatic sites were recorded. Association between metastatic pattern and KRAS expression and FDG indices were analyzed.

RESULTS

KRAS mutation was positive in 40 (43%) patients. Evaluation of FDG indices showed that higher SUVmax (14.0 vs. 11.2, p = 0.004), higher SUVmean (5.3 vs. 4.7, p = 0.005), and higher TLG (301.4 vs. 205.5, p = 0.023) were predictive of KRAS mutation compared to wild-type (WT) KRAS. Lung metastasis was more frequently involved in patients with KRAS mutation (50.0% vs. 22.6%, p = 0.006), and liver metastasis was more frequently involved in patients with WT KRAS (81.1% vs. 55.0%, p = 0.007). Multivariate analysis showed that  primary tumor location (OR 3.92, p = 0.07) and KRAS mutation (OR 2.45, p = 0.09) were significant factors in lung metastasis model.

CONCLUSION

KRAS mutation patients had more frequent lung metastasis and had higher ¹⁸F-FDG uptake compared to WT KRAS in stage IV CRC.

BRAZILIAN CONSENSUS FOR MULTIMODAL TREATMENT OF COLORECTAL LIVER METASTASES. MODULE 3: CONTROVERSIES AND UNRESECTABLE METASTASES

In the last module of this consensus, controversial topics were discussed. Management of the disease after progression during first line chemotherapy was the first discussion. Next, the benefits of liver resection in the presence of extra-hepatic disease were debated, as soon as, the best sequence of treatment. Conversion chemotherapy in the presence of unresectable liver disease was also discussed in this module. Lastly, the approach to the unresectable disease was also discussed, focusing in the best chemotherapy regimens and hole of chemo-embolization.

Imaging in Colorectal Cancer: Progress and Challenges for the Clinicians

The use of imaging in colorectal cancer (CRC) has significantly evolved over the last twenty years, establishing important roles in surveillance, diagnosis, staging, treatment selection and follow up. The range of modalities has broadened with the development of novel tracer and contrast agents, and the fusion of technologies such as positron emission tomography (PET) and computed tomography (CT). Traditionally, the most widely used modality for assessing treatment response in metastasised colon and rectal tumours is CT, combined with use of the RECIST guidelines. However, a growing body of evidence suggests that tumour size does not always adequately correlate with clinical outcomes. Magnetic resonance imaging (MRI) is a more versatile technique and dynamic contrast-enhanced (DCE)-MRI and diffusion-weighted (DW)-MRI may be used to evaluate biological and functional effects of treatment. Integrated fluorodeoxyglucose (FDG)-PET/CT combines metabolic and anatomical imaging to improve sensitivity and specificity of tumour detection, and a number of studies have demonstrated improved diagnostic accuracy of this modality in a variety of tumour types, including CRC. These developments have enabled the progression of treatment strategies in rectal cancer and improved the detection of hepatic metastatic disease, yet are not without their limitations. These include technical, economical and logistical challenges, along with a lack of robust evidence for standardisation and formal guidance. In order to successfully apply these novel imaging techniques and utilise their benefit to provide truly personalised cancer care, advances need to be clinically realised in a routine and robust manner.

Advances in glucose metabolism research in colorectal cancer

Cancer cells uptake glucose at a higher rate and produce lactic acid rather than metabolizing pyruvate through the tricarboxylic acid cycle. This adaptive metabolic shift is termed the Warburg effect. Recently progress had been made regarding the mechanistic understanding of glucose metabolism and associated diagnostic and therapeutic methods, which have been investigated in colorectal cancer. The majority of novel mechanisms involve important glucose metabolism associated genes and miRNA regulation. The present review discusses the contribution of these research results to facilitate with the development of novel diagnosis and anticancer treatment options.

PET-CT in the UK: current status and future directions

Combined positron-emission tomography and computed tomography (PET-CT) has taken the oncological world by storm since being introduced into the clinical domain in the early 21(st) century and is firmly established in the management pathway of many different tumour types. Non-oncological applications of PET-CT represent a smaller but steadily growing area of interest. PET-CT continues to be the focus of a large number of research studies and keeping up-to-date with the literature is important but represents a challenge. Consequently guidelines recommending PET-CT usage need to be revised regularly to encompass new developments. The purpose of this article is twofold: first, it provides a detailed review of the evidence-base underpinning the major uses of PET-CT in clinical practice, which may be of value to a wide-range of individuals, including those directly involved with PET-CT and to a much larger group with limited exposure, but for whom a précis of the current state-of-play may help inform other radiology and multidisciplinary team (MDT) work; the second purpose is as a companion to revised guidelines on evidence-based indications for PET-CT in the UK (being published concurrently) providing a detailed commentary on new indications with a summary of emerging data supporting these additional clinical uses of the technique.

Indeterminate pulmonary nodules in colorectal cancer

AIM: To investigate the clinicopathologic parameters of pulmonary metastasis in colorectal cancer (CRC) patients after lung operation of indeterminate pulmonary nodules (IPNs).

METHODS: From a prospective database of CRC patients, 40 cases that underwent lung operation between November 2008 and December 2012 for suspicious metastatic pulmonary nodules on chest computed tomography (CT) were enrolled. The decision to perform a lung operation was made if the patient met the following criteria: (1) completely resected or resectable primary CRC; (2) completely resectable IPNs; (3) controlled or controllable extrapulmonary metastasis; and (4) adequate general condition and pulmonary function to tolerate pulmonary operation. Lung operation was performed by a thoracic surgeon without CT-guided biopsy for pathologic confirmation.

RESULTS: A total of 40 cases of lung resection was performed in 29 patients. Five patients underwent repeated lung resection. The final pathology result showed metastasis from the CRC in 30 cases (75%) and benign pathology in 10 cases (25%). The primary tumor site was the rectum in 26/30 (86.6%) cases with pulmonary metastasis, but only 3/10 (30%) cases in the benign group had a primary rectal cancer (P = 0.001). Positron emission tomography (PET)-CT was performed for 22/30 (73.4%) patients in the lung metastasis group and for 6/10 (60.0%) patients in the benign group. PET-CT revealed hot uptake of ¹⁸fluorine 2-fluoro-2-deoxy-D-glucose with all IPNs in both groups. The group with pulmonary metastasis had a higher incidence of primary rectal cancer (P = 0.001), a more advanced tumor stage (P = 0.011), and more frequent lymphatic invasion of tumor cells (P = 0.005). Six cases with previous liver metastasectomy were present in the lung metastasis group. Serum carcinoembryonic antigen levels before lung operation were not elevated in any of the patients.

CONCLUSION: The stage and location of the primary tumor and tumor cell infiltration of lymphatics provide useful indicators for deciding on lung resection of IPNs in CRC.