A meta-analysis exploring the role of PET and PET-CT in the management of potentially resectable colorectal cancer liver metastases

Preoperative imaging of colorectal liver metastases: what the radiologist and the multidisciplinary team need to know

The management of patients with colorectal liver metastases (CRLM) has transformed over the past 2 decades. Advances in surgical techniques, systemic therapies, and local treatments have resulted in a paradigm shift. Disease that would once have been considered terminal is now frequently treated aggressively with both a disease-free and overall survival benefit. In line with the expanding range of treatment options, there has been an increase in the volume and complexity of imaging required in the management of these patients to ensure optimal patient selection and outcome. The radiologist plays a pivotal role in interpreting these studies, conveying the relevant information and informing the discussion at multidisciplinary team meetings. The purpose of this review is to provide an update for radiologists on the current surgical management of patients with CRLM highlighting specific imaging information that is required by the multidisciplinary team when assessing resectability and/or the need for additional liver-directed therapies.

Exploring Potential Epigenetic Biomarkers for Colorectal Cancer Metastasis

Metastatic progression is a complex, multistep process and the leading cause of cancer mortality. There is growing evidence that emphasises the significance of epigenetic modification, specifically DNA methylation and histone modifications, in influencing colorectal (CRC) metastasis. Epigenetic modifications influence the expression of genes involved in various cellular processes, including the pathways associated with metastasis. These modifications could contribute to metastatic progression by enhancing oncogenes and silencing tumour suppressor genes. Moreover, specific epigenetic alterations enable cancer cells to acquire invasive and metastatic characteristics by altering cell adhesion, migration, and invasion-related pathways. Exploring the involvement of DNA methylation and histone modification is crucial for identifying biomarkers that impact cancer prediction for metastasis in CRC. This review provides a summary of the potential epigenetic biomarkers associated with metastasis in CRC, particularly DNA methylation and histone modifications, and examines the pathways associated with these biomarkers.

Plasma metabolomics, lipidomics and cytokinomics profiling predict disease recurrence in metastatic colorectal cancer patients undergoing liver resection

Purpose

In metastatic colorectal cancer (mCRC) patients (pts), treatment strategies integrating liver resection with induction chemotherapy offer better 5-year survival rates than chemotherapy alone. However, liver resection is a complex and costly procedure, and recurrence occurs in almost 2/3rds of pts, suggesting the need to identify those at higher risk. The aim of this work was to evaluate whether the integration of plasma metabolomics and lipidomics combined with the multiplex analysis of a large panel of plasma cytokines can be used to predict the risk of relapse and other patient outcomes after liver surgery, beyond or in combination with clinical morphovolumetric criteria.

Experimental design

Peripheral blood metabolomics and lipidomics were performed by 600 MHz NMR spectroscopy on plasma from 30 unresectable mCRC pts treated with bevacizumab plus oxaliplatin-based regimens within the Obelics trial (NCT01718873) and subdivided into responder (R) and non-R (NR) according to 1-year disease-free survival (DFS): ≥ 1-year (R, n = 12) and < 1-year (NR, n = 18). A large panel of cytokines, chemokines, and growth factors was evaluated on the same plasma using Luminex xMAP-based multiplex bead-based immunoassay technology. A multiple biomarkers model was built using a support vector machine (SVM) classifier.

Results

Sparse partial least squares discriminant analysis (sPLS-DA) and loading plots obtained by analyzing metabolomics profiles of samples collected at the time of response evaluation when resectability was established showed significantly different levels of metabolites between the two groups. Two metabolites, 3-hydroxybutyrate and histidine, significantly predicted DFS and overall survival. Lipidomics analysis confirmed clear differences between the R and NR pts, indicating a statistically significant increase in lipids (cholesterol, triglycerides and phospholipids) in NR pts, reflecting a nonspecific inflammatory response. Indeed, a significant increase in proinflammatory cytokines was demonstrated in NR pts plasma. Finally, a multiple biomarkers model based on the combination of presurgery plasma levels of 3-hydroxybutyrate, cholesterol, phospholipids, triglycerides and IL-6 was able to correctly classify patients by their DFS with good accuracy.

Conclusion

Overall, this exploratory study suggests the potential of these combined biomarker approaches to predict outcomes in mCRC patients who are candidates for liver metastasis resection after induction treatment for defining personalized management and treatment strategies.

Diagnostic value of [68Ga]Ga-FAPI-04 in patients with colorectal cancer in comparison with [18F]F-FDG PET/CT

Purpose

This study aimed to compare the diagnostic performance of [68Ga]Ga-FAPI-04 PET/CT and [18F]F-FDG PET/CT in primary and metastatic colorectal cancer (CRC) lesions.

Methods

This single-center preliminary clinical study (NCT04750772) was conducted at the Peking University Cancer Hospital & Institute and included 61 participants with CRC who underwent sequential evaluation through PET/CT with [18F]F-FDG and [68Ga]Ga-FAPI-04. Their PET/CT images were analysed to quantify the uptake of the two tracers in the form of maximum standardised uptake (SUVmax) values and target-to-background ratio (TBR), which were then compared using Wilcoxon's signed-rank test. The final changes in the tumour-node-metastasis (TNM) stage of all participants were recorded.

Results

Of all the participants, 21 were treatment naïve and 40 had been previously treated. In primary CRC lesions, the average TBRs of [68Ga]Ga-FAPI-04 and [18F]F-FDG were 13.3 ± 8.9 and 8.2 ± 6.5, respectively. The SUVmax of [68Ga]Ga-FAPI-04 in signet-ring/mucinous carcinomas (11.4 ± 4.9) was higher than that of [18F]F-FDG (7.9 ± 3.6) (P = 0.03). Both median SUVmax in peritoneal metastases and TBR in liver metastases of [68Ga]Ga-FAPI-04 were higher than those of [18F]F-FDG (5.2 vs. 3.8, P < 0.001; 3.7 vs. 1.9, P < 0.001, respectively). Compared with [18F]F-FDG PET/CT, clinical TNM staging based on [68Ga]Ga-FAPI-04 PET/CT led to upstaging and downstaging in 10 (16.4%) and 5 participants (8.2%), respectively. Therefore, the treatment options were changed in 13 participants (21.3%), including 9 with additional chemo/radiotherapy and/or surgery and others with avoidance or narrowed scope of surgery.

Conclusion

[68Ga]Ga-FAPI-04 showed potential as a novel PET/CT tracer to detect lymph nodes and distant metastases, which improved CRC staging, thus prompting the optimisation or adjustment of treatment decisions.

Role of Positron Emission Tomography/Computed Tomography in Gastrointestinal Malignancies: A Brief Review and Pictorial Essay

Positron emission tomography/computed tomography (PET/CT) is increasingly becoming a mainstay in diagnosis and management of many malignant disorders. However, its role in the assessment of gastro-intestinal lesions is still evolving. The aim of this review was to demonstrate the areas, where PET/CT is impactful and where it has limitations. This will allow for us to reduce unnecessary investigations and develop methods to overcome the limitations.

The management of colorectal liver metastases amenable of surgical resection: How to shape treatment strategies according to clinical, radiological, pathological and molecular features

Metastatic colorectal cancer (mCRC) patients have poor chances of long term survival, being < 15% of them still alive after 5 years from diagnosis. Nonetheless, patients with colorectal liver metastases (CRLM) may be eligible for metastases resection thus being able to achieve long-term disease remission and survival. The likelihood for patients with CRLM of being or becoming eligible for liver metastasectomy is increasing, thanks to the evolution of surgical techniques, the availability of active systemic treatments and the widespread diffusion of experienced multidisciplinary boards to manage these patients. However, disease relapse after liver surgery is common and occurs in two-thirds of resected patients. Therefore, adequate radiological staging and risk stratification is crucial for the optimal selection of patients candidate to surgery in order to maximize the benefit-risk ratio of liver metastasectomy and to individualize the treatment strategy. Based on the multidimensional assessment, three possible approaches are available: upfront liver surgery followed by adjuvant chemotherapy, perioperative chemotherapy preceding and following liver surgery, and an upfront systemic treatment including chemotherapy plus a targeted agent, both chosen according to patients' and tumours' characteristics, then followed by liver surgery if indicated. In this review, we describe the most important factors impacting the therapeutic choices in patients with resectable and potentially resectable CRLM, and we discuss the most promising factors that may reshape the future decision-making process of these patients.

Does 18F-FDG PET/CT change the surgical management of potentially resectable colorectal liver metastases?

PURPOSE

Resectability assessment of patients with colorectal liver metastases is based on computed tomography and liver magnetic resonance imaging. Addition of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography has been recommended, but the impact of the added information remains unclear. The primary aim of this study was to determine how preoperative positron emission tomography/computed tomography changed management in patients with potentially resectable colorectal liver metastases. The secondary aim was to investigate whether findings on positron emission tomography/computed tomography correlated to metastatic disease in cases with extended surgery and influenced oncological outcomes.

METHODS

A retrospective observational study of the impact of adding positron emission tomography/computed tomography to conventional imaging in the surgical decision-making of colorectal liver metastases. All patients with colorectal liver metastases diagnosed by conventional imaging were included and assessed by a multidisciplinary team conference at Umeå University Hospital between June 2013 and December 2017. Eligibility criteria were all patients with potentially resectable colorectal liver metastases. Patients who underwent preoperative positron emission tomography/computed tomography in addition to conventional radiology were compared with those who underwent conventional imaging only.

RESULTS

151/220 patients underwent preoperative positron emission tomography/computed tomography. Findings on positron emission tomography/computed tomography changed the management in 10.6% of the patients. Eight patients were excluded from surgery after detection by positron emission tomography/computed tomography of extrahepatic disease. Eight patients underwent more extended surgery than initially planned due to positron emission tomography/computed tomography. Five of these positron emission tomography-positive resected sites were verified by pathology as metastatic disease. No difference in overall survival was seen following surgical resection in patients with and without a preoperative positron emission tomography/computed tomography.

CONCLUSIONS

Preoperative positron emission tomography/computed tomography resulted in a changed surgical management in 10.6% of cases in a selected cohort.

Clinical Significance and Prognostic Value of the Maximum Standardized Uptake Value of 18F-Flurodeoxyglucose Positron Emission Tomography-Computed Tomography in Colorectal Cancer

Background

The role of ¹⁸F-flurodeoxyglucose (¹⁸F-FDG) positron emission tomography–computed tomography (PET/CT) in colorectal cancer (CRC) remains unclear. This study aimed to explore the association of the maximum standardized uptake value (SUVmax), a parameter of ¹⁸F-FDG PET/CT, with KRAS mutation, the Ki-67 index, and survival in patients with CRC.

Methods

Data of 66 patients with CRC who underwent ¹⁸F-FDG PET/CT was retrospectively collected in our center. The clinical significance of the SUVmax in CRC and the association of the SUVmax with KRAS mutation and the Ki-67 index were determined. A meta-analysis was conducted by a systematic search of PubMed, Web of Science, and CNKI databases, and the data from published articles were combined with that of our study. The association of the SUVmax with KRAS mutation and the Ki-67 index was determined using the odds ratio to estimate the pooled results. The hazard ratio was used to quantitatively evaluate the prognosis of the SUVmax in CRC.

Results

By analyzing the data of 66 patients with CRC, the SUVmax was found not to be related to the tumor-node-metastasis stage, clinical stage, sex, and KRAS mutation but was related to the tumor location and nerve invasion. The SUVmax had no significant correlation with the tumor biomarkers and the Ki-67 index. Data of 17 studies indicated that the SUVmax was significantly increased in the mutated type compared with the wild type of KRAS in CRC; four studies showed that there was no remarkable difference between patients with a high and low Ki-67 index score regarding the SUVmax. Twelve studies revealed that the SUVmax had no significant association with overall survival and disease-free survival in CRC patients.

Conclusions

Based on the combined data, this study demonstrated that the SUVmax of ¹⁸F-FDG PET/CT was different between colon and rectal cancers and associated with KRAS mutation but not the Ki-67 index; there was no significant association between the SUVmax and survival of patients with CRC.

Changes in treatment intent and target definition for preoperative radiotherapy after 18F-Fluorodeoxyglucose positron emission tomography in rectal cancer: A Meta-analysis

PURPOSE

To evaluate the impact of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) on changes in treatment plan and target definition for preoperative radiotherapy in patients with rectal cancer.

METHODS

Embase, PubMed, and Cochrane Library were searched up to November 2020 for all studies investigating the role of preoperative FDG PET in patients who underwent neoadjuvant radiotherapy before curative-intent surgery. The proportion of patients whose treatment plan (curative vs. palliative intent) or target definition was changed after FDG PET was analyzed. A random-effects model was used for pooled analysis. The change in target definition was compared between conventional radiological imaging-based target volume [gross tumor volume (GTV) or planning target volume (PTV)] and PET-based target volume (GTV or PTV) using the standardized mean difference (SMD) and 95% confidence interval (CI).

RESULTS

A total of 336 patients from twelve studies were included. In eight studies, PET changed either the treatment intent or target definition in 24.8% of patients (95% CI 15.1% to 37.9%, I² = 69%). In ten studies, the PET-based GTV was lower than the conventional imaging-based target volume (SMD -7.0, 95% CI -1.39 to -0.01). However, there was no significant difference between conventional imaging-based and PET-based PTV (SMD -0.07, 95% CI -0.75 to 0.62). In six studies evaluating the initial staging based on PET, the initial staging (nodal or metastasis status) was changed in 53 of 229 patients (23.1%). Newly detected or additional distant metastases were identified in 22 patients (9.6%) after FDG PET.

CONCLUSION

The use of FDG PET influences radiotherapy planning in a fourth of patients with rectal cancer. FDG PET can provide additive information for accurate tumor delineation, although PET-based PTV did not significantly change. These findings suggest that FDG PET may be beneficial to patients with rectal cancer before establishing a radiotherapy plan.

Imaging of colorectal cancer liver metastases using contrast-enhanced US, multidetector CT, MRI, and FDG PET/CT: a meta-analysis

BACKGROUND

Imaging of colorectal cancer liver metastases (CRCLMs) has improved in recent years. Therefore, the role of current imaging techniques needs to be defined.

PURPOSE

To assess the diagnostic performance of contrast-enhanced ultrasound (CEUS), multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), and fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the detection of CRCLMs.

MATERIAL AND METHODS

PubMed database was searched for articles published during 2000-2019. Inclusion criteria were as follows: diagnosis/suspicion of CRCLMs; CEUS, MDCT, MRI, or FDG PET/CT performed for the detection of CRCLMs; prospective study design; histopathologic examination, intraoperative findings and/or follow-up used as reference standard; and data for calculating sensitivity and specificity reported.

RESULTS

Twelve prospective studies were assessed, including 536 patients with CRCLMs (n = 1335). On a per-lesion basis, the sensitivity of CEUS, MDCT, MRI, and FDG PET/CT was 86%, 84%, 89%, and 62%, respectively. MRI had the highest sensitivity on a per-lesion analysis. CEUS and MDCT had comparable sensitivities. On a per-patient basis, the sensitivity and specificity of CEUS, MDCT, MRI, and FDG PET/CT was 80% and 97%, 87% and 95%, 87% and 94%, and 96% and 97%, respectively. The per-patient sensitivities for MRI and MDCT were similar. The sensitivity for MRI was higher than that for CEUS, MDCT, and FDG PET/CT for lesions <10 mm and lesions at least 10 mm in size. Hepatospecific contrast agent did not improve diagnostic performances.

CONCLUSION

MRI is the preferred imaging modality for evaluating CRCLMs. Both MDCT and CEUS can be used as alternatives.

When What You See Is Not Always What You Get: Raising the Bar of Evidence for New Diagnostic Imaging Modalities

Even though prostate-specific membrane antigen (PSMA)-positron emission tomography (PET)-computed tomography (CT) is more accurate than conventional imaging in prostate cancer patients, its impact on patient-relevant outcomes is unknown. We argue that more evidence is required before using PSMA-PET-CT as the standard of care for staging.

Effect of PET-CT on disease recurrence and management in patients with potentially resectable colorectal cancer liver metastases. Long-term results of a randomized controlled trial

BACKGROUND

Preoperative evaluation of resectable colorectal cancer liver metastases with positron emission tomography (PET) combined with computed tomography (PET-CT) is used extensively. The PETCAM trial evaluated the effect of PET-CT (intervention) vs no PET-CT (control) on surgical management. PET-CT resulted in 8% change in surgical management, therefore, we aimed to compare long-term outcomes (disease-free [DFS], overall survival [OS]).

METHODS

Trial recruitment (2005-2010) had prospective follow-up until 2013. Events from 2013 to 2017 were collected retrospectively. Survival was described by the Kaplan-Meier method and compared with log-rank test. Oncologic risk factors were calculated using Cox proportional hazard models.

RESULTS

Among 404 patients randomized, there were no differences in DFS (hazard ratio [HR] = 1.13; 95% confidence interval [CI], 0.89 to 1.43) or OS (HR, 1.02; 95% CI, 0.78-1.32) between groups. For all patients randomized, median DFS (PET-CT vs no PET-CT) was 16 months (95% CI, 13-18) and 15 months (95% CI, 11-22), P = .33. For patients who underwent liver resection (n = 368), DFS (17 vs 16 months, P = .51) and OS (58 months vs 52 months, P = .90) were similar between groups, respectively. Risk factors for DFS and OS were age, tumor size, node-positive disease, extrahepatic metastases and disease-free duration.

CONCLUSION

Preoperative PET-CT changes surgical management in a small percentage of cases, without effect on recurrence rates or long-term survival.