Comparison of preoperative whole-body positron emission tomography with MDCT in patients with primary colorectal cancer

Colon cancer: the 2023 Korean clinical practice guidelines for diagnosis and treatment

Colorectal cancer is the third most common cancer in Korea and the third leading cause of death from cancer. Treatment outcomes for colon cancer are steadily improving due to national health screening programs with advances in diagnostic methods, surgical techniques, and therapeutic agents.. The Korea Colon Cancer Multidisciplinary (KCCM) Committee intends to provide professionals who treat colon cancer with the most up-to-date, evidence-based practice guidelines to improve outcomes and help them make decisions that reflect their patients' values and preferences. These guidelines have been established by consensus reached by the KCCM Guideline Committee based on a systematic literature review and evidence synthesis and by considering the national health insurance system in real clinical practice settings. Each recommendation is presented with a recommendation strength and level of evidence based on the consensus of the committee.

Clinical Practice Guideline: Anal Cancer—Diagnosis, Treatment and Follow-up

BACKGROUND

The number of anal cancer diagnoses has been rising steadily, so that the incidence has doubled in the past 20 years. Almost all anal cancers are induced by persistent infection with human papillomaviruses. Hitherto the care of patients with anal cancer has been heterogeneous and little experience exists with the primary management of anal cancer.

METHODS

The guideline was developed in accordance with the requirements of the German Guideline Program in Oncology. In line with the GRADE approach, the certainty of the evidence was assessed on the outcome level following a systematic literature search. Interdisciplinary working groups were set up to compile suggestions for recommendations, which were discussed and agreed upon in a formal consensus conference.

RESULTS

Ninety-three recommendations and statements were developed. No high-quality evidence was available to support recommendations for or against the treatment of stage I anal cancer with local excision alone as an alternative to chemoradiotherapy. Chemoradiotherapy is the gold standard in the treatment of stages II–III. Among other aspects regarding the timing and extent of response evaluation after chemoradiotherapy, the guideline panel recommended against obtaining a biopsy in the event of complete clinical response. Owing to lack of confidence in the available evidence, only open recommendations were given for treatment of stage IV.

CONCLUSION

This evidence-based clinical practice guideline provides a sound basis for optimizing the interdisciplinary, cross-sector care of anal cancer patients. Among other areas, gaps in research were identified with respect to the care of patients with early-stage or metastatic anal cancer. Approaches such as chemoradiotherapy combined with regional deep hyperthermia require further investigation. The role for immunotherapy in the management of metastasized anal cancer has also been insufficiently explored to date.

Is 18F-FDG PET/CT an Accurate Way to Detect Lymph Node Metastasis in Colorectal Cancer: A Systematic Review and Meta-Analysis

Aims

The purpose of this study was to assess the diagnostic value of ¹⁸F-fluorodeoxy-glucose positron emission tomography/computed tomography (FDG PET/CT) for detection of lymph node (LN) metastasis of colorectal cancer. Material and Methods. A computerized search was performed to determine the relevant articles, published before October 2019. Stata Statistical Software, version 15.0, and Meta-Disc (version 1.4) were used for the meta-analysis.

Results

the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 0.65, 0.75, 4.57, and 0.37 respectively. Studies that used SUV_max cut-off value (≤2.5) demonstrated the best accuracy.

Conclusion

¹⁸F-FDG PET/CT shows a low sensitivity and high specificity for detecting the metastasis of LNs in patients with newly diagnosed colorectal cancer.

Role of fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography in gastrointestinal cancers

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a routine imaging modality for many malignancies and its use is currently increasing. In the present review article, we will summarize the evidence for FDG-PET/CT use in digestive cancers (excluding neuroendocrine tumours), and review the existing recommendations. While PET/CT is nowadays considered to be an important tool in the initial workup of oesophageal and anal cancers, new data are emerging regarding its use in assessing therapeutic efficacy, radiotherapy treatment planning, and detection of recurrence in case of isolated tumour marker elevation. Moreover, PET/CT may help decision making by detecting distant metastatic sites especially in potentially resectable metastatic colorectal cancer and, to a lesser extent, in localized gastric and pancreatic cancers. Finally, incidental focal colonic FDG uptakes require exploration by colonoscopy, as they are often associated with premalignant or malignant lesions.

Diagnostic accuracy and impact on management of (18)F-FDG PET and PET/CT in colorectal liver metastasis: a meta-analysis and systematic review

PURPOSE

The first aim of the review (aim 1) was to obtain the diagnostic performance values of (18)F-FDG PET for the detection and staging of liver metastases in patients with colorectal cancer (CRC), the second aim (aim 2) was to compare PET and conventional imaging modalities, and the third aim (aim 3) was to evaluate the impact of PET on patient management. The incidence of extrahepatic disease (EHD) detected by PET is also reviewed.

METHODS

A comprehensive search was performed on PubMed/MEDLINE for studies evaluating PET and PET/CT in CRC patients with liver metastases up to June 2014. For inclusion PET had to have been performed prior to surgery, there had to be at least 18 patients in the study, and the reported data had to allow calculation of 2 × 2 contingency tables (for aim 1). A total of 18 studies were eligible for at least one of the three intended subanalyses including a total of 1,059 patients. Pooled sensitivity, specificity and accuracy and the corresponding 95 % confidence intervals were derived from the contingency tables on a patient basis (patient-based analysis, PBA) and a lesion basis (lesion-based analysis, LBA) for eight studies.

RESULTS

Pooled sensitivity and specificity of PET on PBA were both 93 %. Corresponding values for LBA were 60 % and 79 %, respectively. Areas under the summary ROC were 0.97 for PBA and 0.67 for LBA. Regarding aim 2, PET had a slightly lower sensitivity than MRI and CT on PBA (93 %, 100 % and 98 %, respectively) and LBA (66 %, 89 % and 79 %, respectively) but appeared to be more specific than MRI and CT (86 %, 81 % and 67 %, respectively). PET findings resulted in changes in the management of a mean of 24 % of patients. The mean incidence of PET-based EHD was 32 %.

CONCLUSION

This meta-analysis suggests that FDG PET/CT is highly accurate for the detection of liver metastases on a patient basis but less accurate on a lesion basis. Compared to MRI, PET is less sensitive but more specific and affects the management of about one-quarter of patients.

Positron emission tomography/computed tomography in the staging of colon cancer

Purpose

Accurate preoperative staging of colon cancer is essential for providing the optimal treatment strategy and evaluating the expected prognosis. The aim of this study is to assess the value of positron emission tomography/computed tomography (PET/CT) over conventional studies in the staging of colon cancer.

Methods

A total of 266 colon cancer patients diagnosed between January 2008 and December 2010 were assessed with both PET/CT and conventional studies. Discordance with PET/CT and conventional studies were evaluated, and changes in the management strategy were assessed for each stage. Discordant findings were verified by using intraoperative examination, pathology reports, and follow-up imaging studies.

Results

Multidetector computed tomography (MDCT) and PET/CT showed similar accuracy in detecting lymph node metastasis in patients with clinical stage III (36.2% vs. 42%, P = 0.822) and stage IV (60.3% vs. 63.5%, P = 0.509) disease. PET/CT led to a change in management strategy for 1 of 40 patients (2.5%) with clinical stage I, 0 of 25 patients (0%) with stage II, 9 of 138 patients (6.5%) with stage III, and 8 of 63 patients (12.7%) with stage IV disease.

Conclusion

PET/CT changed the management plan in 6.5% of patients with clinical stage III and 12.7% of patients with clinical stage IV colon cancer. Our findings suggest that PET/CT may be considered as a routine staging tool for clinical stage III and IV colon cancers.

Molecular mechanisms of [18F]fluorodeoxyglucose accumulation in liver cancer

To elucidate the molecular mechanisms underlying the insufficient sensitivity in the detection of hepatocellular carcinoma (HCC) by [18F] 2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET), the characteristics of glucose metabolism-related protein expression in HCC were examined in liver metastasis from colorectal cancer (Meta). Thirty-four patients (14 Meta and 20 HCC) who underwent FDG-PET and hepatectomy were studied. The relationships between the maximum standardized uptake value (SUV) in tumors and the mRNA expression of glucose metabolism-related proteins [hexokinase (HK), glucose transporter 1 (GLUT1), and glucose-6-phosphatase (G6Pase)] and proliferating cell nuclear antigen (PCNA) were examined in snap-frozen specimens with quantitative PCR. Tumor detection rates were lower in HCC (15/20) compared to Meta (13/14) patients. HK and GLUT1 expression was lower and G6Pase expression was higher in HCC compared to Meta. In particular, GLUT1 overexpression was 92-fold in Meta and 11-fold in HCC compared to the surrounding liver. The SUV correlated with GLUT1 and PCNA expression in HCC, but not Meta patients. Of note, four cases of poorly differentiated (P/D) HCC compared to moderately differentiated (M/D) HCC produced completely different results for FDG uptake (SUV, 14.4 vs. 4.0) and mRNA expression (G6Pase expression, 0.007 vs. 1.5). Variations in the expression of glucose metabolism-related enzymes between HCC and Meta patients are attributed to origin or degree of differentiation. Low FDG uptake in M/D HCC reflected low GLUT1 and high G6Pase expression, while high FDG accumulation in P/D HCC could reflect increased GLUT1 and decreased G6Pase expression. These results may explain why M/D HCC is not detected as sensitively by FDG-PET.

Routine use of positron-emission tomography/computed tomography for staging of primary colorectal cancer: does it affect clinical management?

Background

The use of positron emission tomography-computed tomography (PET/CT) for the preoperative staging of patients with colon and rectal cancer has increased steadily over the last decade. The aim of this study was to evaluate the effect of PET/CT on the preoperative staging and clinical management of patients with colorectal cancer.

Methods

Between December 2010 and February 2012, 64 consecutive patients with colorectal cancer were evaluated with both PET/CT scans and conventional preoperative imaging studies. We prospectively recorded the medical reports of these patients. The PET/CT findings were compared with conventional imaging studies and the rate of over-staging or down-staging and changes in clinical management were evaluated. The correlation of the PET/CT with the conventional imaging was compared by a kappa agreement coefficient. Differences in the accuracy for N and T staging were assessed by χ2 and related-samples marginal homogeneity tests.

Results

Thirty-nine (60.9%) patients had rectal cancer and 25 (39.1%) had colon cancer. Based on PET/CT, additional lesions were found in 6 (9.4%) of the patients: hilar and paratracheal lesions in 4 patients, hepatic in 1 and supraclavicular in 1 patient. In four of six patients, detailed imaging studies or biopsies revealed chronic inflammatory changes. Hepatic and supraclavicular involvement was confirmed in two patients. Therefore, the false positivity rate of PET/CT was 6.25%. Based on the additional PET/CT, 2 (3.2%) patients had a change in surgical management. A chemotherapy regimen was administered to the patient with a 1.5 cm hepatic metastasis near the right hepatic vein; for another patient with an identified supraclavicular lymph node metastasis, a simultaneous excision was performed.

Conclusions

Routine use of PET/CT for preoperative staging did not impact disease management for 96.8% of our patients. The results of our study conclude that PET/CT should not be routinely used for primary staging of colorectal cancer. More studies are required for identifying the subgroup of patients who might benefit from a PET/CT in their initial staging.

A systematic review and meta-analysis of pretherapeutic lymph node staging of colorectal cancer by 18F-FDG PET or PET/CT

The purpose of the present study was to conduct a systematic review and meta-analysis of the published literature to evaluate the diagnostic performance of fluorine-18 2-fluoro-2-deoxy-D-glucose (18F-FDG) PET in the pretherapeutic assessment of nodal staging in patients with colorectal cancer (CRC). We conducted a systematic MEDLINE search of articles in the published literature (last update, February 2012). Two reviewers independently assessed the methodological quality of each study. We estimated pooled sensitivity, specificity, summary receiver operating characteristic curves, and summary likelihood ratios. A total of 409 patients from 10 studies were analyzed. The pooled estimates of sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of 18F-FDG PET [PET/computed tomography (CT)] in the detection of pretherapeutic lymph node involvement in patients with CRC were 42.9% [95% confidence interval (CI): 36.0-50.0%], 87.9% (95% CI: 82.6-92.0%), 2.82 (95% CI: 1.96-4.07), and 0.69 (95% CI: 0.62-0.78), respectively. There is no solid evidence to support the routine clinical application of 18F-FDG PET (PET/CT) in the pretherapeutic evaluation of lymph node status in patients with CRC. However, 18F-FDG PET (PET/CT) could be used to strengthen the possibility of suspected metastatic lymph nodes detected by other imaging modalities.

Lymph node harvest in colon and rectal cancer: Current considerations

The prognostic significance of identifying lymph node (LN) metastases following surgical resection for colon and rectal cancer is well recognized and is reflected in accurate staging of the disease. An established body of evidence exists, demonstrating an association between a higher total LN count and improved survival, particularly for node negative colon cancer. In node positive disease, however, the lymph node ratios may represent a better prognostic indicator, although the impact of this on clinical treatment has yet to be universally established. By extension, strategies to increase surgical node harvest and/or laboratory methods to increase LN yield seem logical and might improve cancer staging. However, debate prevails as to whether or not these extrapolations are clinically relevant, particularly when very high LN counts are sought. Current guidelines recommend a minimum of 12 nodes harvested as the standard of care, yet the evidence for such is questionable as it is unclear whether an increasing the LN count results in improved survival. Findings from modern treatments, including down-staging in rectal cancer using pre-operative chemoradiotherapy, paradoxically suggest that lower LN count, or indeed complete absence of LNs, are associated with improved survival; implying that using a specific number of LNs harvested as a measure of surgical quality is not always appropriate. The pursuit of a sufficient LN harvest represents good clinical practice; however, recent evidence shows that the exhaustive searching for very high LN yields may be unnecessary and has little influence on modern approaches to treatment.

Positron emission tomography and colorectal cancer

Colorectal cancer (CRC) is a major cause of cancer-related morbidity and mortality. Molecular imaging using positron emission tomography (PET) is now an integral part of multidisciplinary cancer care. In this review, we discuss the role of PET in CRC including well established indications in the assessment of recurrent disease and emerging applications such as initial staging, monitoring therapy efficacy and using PET for radiotherapy planning. With rapid advancement in imaging technology, we also discuss the future potential of combining PET and magnetic resonance imaging and the use of novel radiotracers.

Prognostic factors for survival after salvage surgery for locoregional recurrence of colon cancer

BACKGROUND

Although locoregional recurrence after rectal cancer resection has been extensively investigated, studies of salvage surgery for locoregionally recurrent colon cancer are scarce. This study aimed to determine the predictors of postsalvage survival for locoregionally recurrent colon cancer.

METHODS

We studied 45 consecutive patients who underwent macroscopically complete resection of locoregionally recurrent colon cancer between April 1988 and December 2007. The primary end point was cancer-specific survival, and 20 clinical variables were analyzed for their prognostic significance.

RESULTS

Cancer-specific 5-year survival for the entire cohort of 45 patients was 46%. Multivariate survival analysis showed that margin status (P = .0311), number of locoregional recurrent tumors (P = .0002), pathological grade (P = .0416), largest tumor diameter (P = .0247), and distant metastasis (P = .0006) were independently associated with cancer-specific survival.

CONCLUSIONS

Salvage surgery for locoregional recurrence of colon cancer can provide a chance for long-term survival in selected patients.

Trends in nontherapeutic laparotomy rates in patients undergoing surgical therapy for hepatic colorectal metastases

Surgery is the treatment of choice in selected patients with hepatic colorectal metastases. Despite improvements in preoperative imaging, patients can undergo unnecessary nontherapeutic laparotomy. The aim of this study was to examine trends in nontherapeutic laparotomy rates in patients undergoing planned surgical therapy for hepatic colorectal metastases. Data from 530 operations (461 patients) undergoing potentially curative surgical therapy for colorectal liver metastases between 1994 and 2005 were analyzed. The incidence of nontherapeutic laparotomy was determined and factors associated with nontherapeutic laparotomy were identified. Overall, 49 nontherapeutic laparotomies were performed (9.2%). Higher nontherapeutic laparotomy rates were seen in patients with multiple metastases and tumor size >5 cm (both P < 0.05). Preoperative positron emission tomography (PET) imaging was associated with lower risk of nontherapeutic laparotomy [5.6% versus 12.4%, P = 0.009, odds ratio (OR) = 0.42]. At laparotomy, extrahepatic findings were the reason for nontherapeutic laparotomy in 44.9% of cases. The nontherapeutic laparotomy rate significantly decreased over time (14.9% for 1994-1997 versus 9.6% for 1998-2001 versus 4.7% for 2002-2005; P = 0.003). While patients in each time period were similar with regard to tumor specific factors, utilization of PET imaging (P < 0.001) as well as resection plus ablation (P = 0.004) increased over time. We conclude that prevalence of nontherapeutic laparotomy for patients undergoing surgical exploration for hepatic colorectal metastases has decreased significantly in recent years to less than 5%. The reasons for this trend are probably multifactorial and may include improved preoperative assessment, such as PET imaging, as well as salvage surgical options.