Clinical utility and cost-effectiveness of routine preoperative computed tomography scanning in patients with colon cancer

Evaluation of colon cancer prognostic factors by CT and MRI: an up-to-date review

Colorectal cancer (CRC) is a significant global health concern. Prognostication of CRC traditionally relies on the Union for International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC) TNM staging classifications, yet clinical outcomes often vary independently of stage. Despite similarities, rectal and colon cancers are distinct in their diagnostic methodologies and treatments, with MRI and CT scans primarily used for staging rectal and colon cancers, respectively. This paper examines the challenges in accurately assessing prognostic factors of colon cancer such as primary tumor extramural extension, retroperitoneal surgical margin (RSM) involvement, extramural vessel invasion (EMVI), and lymph node metastases through preoperative CT and MRI. It highlights the importance of these factors in risk stratification, treatment decisions, and surgical planning for colon cancer patients. Advancements in imaging techniques are crucial for improving clinical management and optimizing patient outcomes, underscoring the necessity for ongoing research to refine diagnostic methods and incorporate novel findings into practice.

The Accuracy of Different Modalities Used for Preoperative Primary Tumour Localisation in Operated Colorectal Cancer Patients

Aim Colonoscopy and computed tomography (CT) scans of the abdomen and pelvis are routine pre-operative assessment tools in colorectal cancer (CRC) patients. There have been some discrepancies regarding the location of cancer when seen by colonoscopy versus CT scan. The purpose of this study was to compare the accuracy of a colonoscopy with a computed tomography (CT) scan of the abdomen and pelvis with contrast, which is done routinely before surgery to localise the exact site of the tumour within the large bowel, whilst comparing both to the operative, gross and histopathology findings of the exact location. Methods A retrospective study was carried out on 165 colorectal cancer patients operated on between January 1, 2010, and December 31, 2014, using electronic hospital records that were reviewed anonymously, comparing the location of cancer within the large bowels as was found on colonoscopy and CT scan of the abdomen and pelvis with contrast, comparing both to post-operative histopathology specimen or intra-operative assessment in cases where no resection of the primary tumour was performed. Results CT and colonoscopy were both accurate in diagnosing 70.5% of cases that had done both investigations pre-operatively. The best results were obtained when the cancer was located in the caecum as confirmed post-operatively; the combined accuracy rate was 100%. CT was accurate, whilst colonoscopy was not in eight (6.2%) cases (all are rectal or sigmoid cancers), and colonoscopy was accurate and CT was not in 12 cases, 10 of them were rectal and two were ascending colonic. Colonoscopy was not performed in 36 (21%) cases for a variety of reasons, including large bowel obstruction or perforation on presentation. In 32 of these cases, CT scan managed to accurately predict the location of cancer (mostly rectal and caecal), and CT scan was inaccurate in 20.6% of cases (34 out of 165), whilst colonoscopy was inaccurate in 13.9% of cases (18 out of 129). Conclusion Colonoscopy is more accurate in localising colorectal cancers than CT scan of the abdomen and pelvis with contrast. CT scan diagnoses regional and distant spread of colorectal cancers such as nodal status, invasion of neighbouring organs and/or peritoneum and the presence of liver metastases, whilst colonoscopy is limited to intraluminal diagnosis but can be both a diagnostic and therapeutic tool, with higher accuracy, in general, in localising colorectal cancers. Both CT scan and colonoscopy were equal in appendicular, caecal, splenic flexure and descending colon cancer localisation accuracy.

Diagnostic accuracy of ≥ 16-slice spiral computed tomography for local staging of colon cancer: A systematic review and meta-analysis

BACKGROUND

Colorectal cancer is one of the most common cancers worldwide with high mortality and is classified as a single entity, although colon cancer and rectal cancer have largely different diagnoses, treatments, surgical methods, and recurrence rates. ≥ 16-slice spiral computed tomography (SCT) is mostly applied to detect the local stage of colon cancer; however, its diagnostic accuracy and whether it is conducive to distinguishing between high-risk and low-risk colon cancer are unclear.

AIM

To systematically review the diagnostic accuracy of ≥ 16-slice SCT for local staging of colon cancer.

METHODS

Based on the PubMed, EMBASE, Cochrane Library, and Web of Science databases, computers were used to search the literature from the establishment of the database to April 2021, and the results of the diagnostic tests on ≥ 16-slice SCT for local staging of colon cancer were collected according to the inclusion criteria. The data were then extracted and assessed on the basis of the Quality Assessment Checklist of the Institute of Economics of Canada, Reference Citation Analysis (https://www.referencecitationanalysis.com/). Afterward, a meta-analysis was performed using the statistical software Meta-disc 14.0 and Stata 15.0.

RESULTS

Eleven studies that provided data on 1613 subjects with computed tomography diagnostic tests were included in this study. Meta-analysis revealed that the pooled sensitivity, pooled specificity, pooled negative likelihood ratio (LR), pooled diagnostic odds ratio, and area under the fitted receiver operating characteristic (ROC) curve of ≥ 16-slice SCT for colon cancer T staging were 0.67 (95%CI: 0.65-0.70), 0.81 (95%CI: 0.80-0.83), 4.13 (95%CI: 2.66-6.41), 0.39 (95%CI: 0.31-0.49), 10.81 (95%CI: 7.33-15.94), and 0.829, respectively, while the specificity, negative LR, diagnostic odds ratio, and area under the fitted ROC curve of ≥ 16-slice SCT for N staging of colon cancer were 0.54 (95%CI: 0.49-0.59), 0.74 (95%CI: 0.70-0.77), 1.92 (95%CI: 1.36-2.70), 0.67 (95%CI: 0.51-0.87), 3.74 (95%CI: 1.76-7.94), and 0.829 respectively. The sensitivity and specificity of ≥ 16-slice SCT for colon cancer T staging were acceptable, while the sensitivity for colon cancer N staging was relatively low, though its specificity was acceptable.

CONCLUSION

≥ 16-slice SCT for local staging of colon cancer has good diagnostic value; however, the accuracy needs to be confirmed by further clinical practice.

Assessment of the Use of Preoperative CT Scan Image for Predicting Lymph Nodes for Resection of Colorectal Cancer: A Retrospective Study

<b><i>Introduction:</i></b> Colorectal cancer (CRC) is the most common cancer that accounts for nearly 10% of the cancers, with 1.36 million people worldwide. Nodal status (N-stage) evaluation was inferior between observers, which considered CT scanning a good N-stage. We hypothesized that CRC patients’ preoperative CT scan imaging predicts the nodal and metastatic stage. <b><i>Methods:</i></b> This noninterventional retrospective study was carried out using patients’ medical records, including medical history and results of diagnostic tests, and preoperative clinical and pathological stages. All direct identifiers have been removed from all patient data. This study included 96 patients who underwent resection curative surgery for CRC at the Tertiary Hospital, Sudan, between March 2009 and December 2020. <b><i>Results:</i></b> The median age was 69 years (47–74 years), and 49 (51.04%) were female. The tumor stage of the patients was 4, 11, 74, and 7 as T1, T2, T3, and T4, respectively. A total of 38 patients with a malignant spread in lymph nodes were observed, and the median lymph node count was 11 (range 4–52). Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, positive predictive value (PPV), negative predictive value (NPV), and accuracy calculated for the malignant lymph nodes were 75.56% (95% CI: 60.46–87.12%), 45.10% (95% CI: 31.13–59.66%), 1.38 (95% CI: 1.02–1.86), 0.54 (95% CI: 0.30–0.98), 54.84% (95% CI: 47.38–62.09%), 67.65% (95% CI: 53.53–79.15%), and 59.38% (95% CI: 48.87–69.29%), respectively. <b><i>Conclusion:</i></b> The preoperative CT scan images were used to predict lymph nodes with a diagnostic accuracy of 59.38% for N-stage in patients with CRC.

Do Moderate Surgical Treatment Delays Influence Survival in Colon Cancer?

BACKGROUND

Studies examining treatment delay and survival after surgical treatment of colon cancer have varied in quality and outcome, with little evidence available regarding the safety of longer surgical treatment wait times.

OBJECTIVE

Our study examined the effect of surgical treatment wait times on survival for patients with stage I to III colon cancer.

DESIGN

A subset cohort analysis was performed using data from a prospectively maintained database.

SETTINGS

The study was conducted at a tertiary referral center.

PATIENTS

Data on all of the patients undergoing elective surgery for stage I to III colon cancer from 2006 to 2015 were collected from a prospectively maintained clinical and administrative database.

MAIN OUTCOME MEASURES

We examined the impact of prolonged wait time to surgery on disease-free and overall survival. Patients were divided into 2 groups based on a treatment wait time of ≤30 or >30 days and were compared using a Cox proportional hazards model. A subgroup analysis was performed using alternative treatment delay cutoffs of 60 and 90 days.

RESULTS

There were 908 patients with stage I to III colon cancer treated over the study period, with a median treatment wait time of 38 days (interquartile range, 21-61 days); 368 patients were treated within 30 days, and 540 were treated beyond 30 days from diagnosis. In adjusted multivariate analysis, a treatment delay of >30 days was not associated with decreased disease-free survival (HR = 0.89 (95% CI, 0.61-1.3); p = 0.52) or overall survival (HR = 0.82 (95% CI, 0.63-1.1); p = 0.16). Likewise, subgroup analysis using alternative treatment delay cutoffs of 60 and 90 days did not demonstrate an adverse effect on survival.

LIMITATIONS

This study was limited by retrospective analysis.

CONCLUSIONS

Despite longer median treatment wait times from diagnosis to surgery, with the majority of patients exceeding 30 days and many experiencing delays of 2 to 3 months, no adverse impact on survival was observed. Patients who require additional consultations or investigations preoperatively may safely have their surgery moderately delayed to minimize their perioperative risk without any evidence that this will compromise treatment outcomes. See Video Abstract at http://links.lww.com/DCR/A397.

Accuracy of preoperative T and N staging in colon cancer--a national population-based study

AIM

To select patients for neoadjuvant therapy in colon cancer, there is a need to improve pre-therapeutic locoregional staging. There are now data showing that the TN stage can be adequately assessed by preoperative CT in dedicated centres. In Sweden the use of preoperative CT of the abdomen for staging of the primary tumour is increasing. The aim of this study was to determine to what extent the preoperatively reported radiological TN stage correlates with the histopathological TN stage in an entire population.

METHOD

Data were collected on the preoperative cTN stage according to the radiologist and postoperative pTN stage according to the pathologist on all patients operated on for colon cancer in Sweden 2007-2010. The correlation between cTN stage and pTN stage was calculated using kappa statistics.

RESULTS

T stage was compared in 4373 patients with cT and pT stage. The correlation coefficient was 0.44, indicating fair agreement. The cN and pN correlation coefficient was 0.28, indicating a slight correlation. There was no difference in correlation related to age, gender, tumour location, body mass index or emergent vs elective surgery. A slight difference was seen between different geographical regions.

CONCLUSION

Preoperative CT in an unselected population does not result in an accurate cTN staging as previously reported from dedicated centres. To achieve adequate preoperative cTN staging nationally, the education of radiologists and optimization of the radiological method will be necessary.

Lung and colorectal cancer treatment and outcomes in the Veterans Affairs health care system

Lung cancer (LC) and colorectal cancer (CRC) are the second- and third-most commonly diagnosed cancers in the Veterans Affairs (VA) health care system. While many studies have evaluated the treatment quality and outcomes of various aspects of VA LC and CRC care, there are no known reviews synthesizing this information across studies. The purpose of this literature review was to describe LC and CRC treatment (ie, surgical and nonsurgical) and outcomes (eg, mortality, psychosocial, and other) in the VA health care system as reported in the existing peer-reviewed scientific literature. We identified potential articles through a search of published literature using the PubMed electronic database. Our search strategy identified articles containing Medical Subject Headings terms and keywords addressing veterans or veterans' health and LC and/or CRC. We limited articles to those published in the previous 11 years (January 1, 2003 through December 31, 2013). A total of 230 articles were retrieved through the search. After applying the selection criteria, we included 74 studies (34 LC, 47 CRC, and seven both LC and CRC). VA provides a full array of treatments, often with better outcomes than other health care systems. More work is needed to assess patient-reported outcomes.

Pretreatment staging of colon cancer in the Swedish population

AIM

Preoperative staging of colon cancer according to Swedish national guidelines implies imaging evaluation of the primary tumour, liver and lungs. Failure to adhere to these guidelines results in negative scorings in the national registration system. In the present study we report the extent of compliance with these guidelines.

METHOD

Since 2007 clinical data on all patients diagnosed with colon cancer in Sweden have been collected in a national database. This includes information on pretherapeutic diagnostic imaging performed, pretherapeutic TNM stage and data on treatment and follow-up. All patients diagnosed with colon cancer in Sweden between 2007 and 2010 were included.

RESULTS

Nine thousand and eight-three patients (i.e. 60.5% of all patients) had a complete pretherapeutic radiological evaluation; 65.2% had a CT or MRI of the primary tumour, whereas over 80% had examinations of the liver and lungs. There were no difference related to sex, but more patients under 75 years had a complete evaluation. There were large differences between different regions; one region performed a complete evaluation of 78.3% of all patients. The proportion of patients examined increased from 53.9 to 65.0% during the study period. Elective cases were more frequently evaluated before treatment than those with an emergency presentation.

CONCLUSION

Most patients in Sweden had a complete pretreatment imaging evaluation of the colon cancer with geographical and time-dependent variations. Knowledge of the importance of these variations and correlation of pre- and postoperative TNM stage is warranted, and such studies are ongoing.

Colon cancer: comprehensive evaluation with 64-section CT colonography using water enema as intraluminal contrast agent-a pictorial review

Sixty-four-section CT colonography with water enema combines intracolonic neutral contrast agent with high-resolution CT images of the abdomen. Owing to submillimeter isotropic voxels, high-quality reformatted images are obtained. High-resolution images offer added value for the detection and localization of colonic lesions, evaluation of the local extent of the disease, and depiction, if any, of synchronous colorectal lesions and distant metastases. Sixty-four-section CT colonography with water enema has a major role in the evaluation of patients with colon cancer before planning therapy. It can be used to complement failed or incomplete colonoscopy and investigate the colon in elderly patients.

Prognostic value of preoperative radiological staging assessed by computed tomography in patients with nonmetastatic colon cancer

PURPOSE

This study evaluated the prognostic value of preoperative locoregional staging in patients with colon cancer and who underwent curative resection.

METHODS

A total of 536 consecutive patients who underwent curative resection for colon cancer from February 1999 to November 2007 were prospectively enrolled. The clinicopathological variables, including the radiological staging using computed tomography, were analyzed for the prognostic significance.

RESULTS

The 5-year overall survival rates of the patients with radiological T1, T2, T3, and T4 were 96%, 89%, 75%, and 79%, respectively (P = 0.028). The 5-year overall survival rates were 83%, 76%, and 54%, respectively, for patients with radiological N0, N1, and N2 disease (P < 0.001). The 5-year overall survival rates of the patients with radiological TNM (tumor-node-metastasis) stages I, II, and III were 90%, 81%, and 70%, respectively (P < 0.001) and the 5-year overall survival rates of the patients with pathological TNM stages I, II, and III were 93%, 80%, and 70%, respectively (P = 0.001). On multivariate analysis, the radiological T and N categories remained independent prognostic factors for both overall survival and disease-free survival.

CONCLUSION

Radiological staging is an independent predictor of long-term survival in the preoperative setting.

Right colectomy with simultaneous vascular reconstruction for celiac and superior mesenteric arterial occlusion

INTRODUCTION

Identification of the primary feeding vessel and its removal with corresponding lymphatics is crucial for oncologic bowel resection for colon cancer. However, this notion would be challenged if we encountered abnormal mesenteric vascular anatomy. We report a case of colon cancer with abnormal mesenteric circulation, for whom we performed oncologic colectomy with vascular reconstruction.

PRESENTATION OF CASE

A 61-year-old man presented with obstructing transverse colon cancer. A contrast-enhanced computed tomography (CT) scan showed complete occlusion at the root of the superior mesenteric artery (SMA) and the celiac artery (CA), with evidently dilated marginal artery (MA). An X-ray angiography revealed retrograde arterial blood flow originating from the inferior mesenteric artery (IMA) via the MA, the SMA, and to the CA. At laparotomy, we found remarkably dilated MA with the mid-transverse colon cancer. There were no other communicating vessels between the IMA and the SMA. Right colectomy with proper lymph node dissection was completed, following vascular anastomosis between the MA to the SMA. His postoperative course was uneventful. A postoperative CT angiography showed revascularization of the areas where the SMA and the CA supplied.

DISCUSSION

In this patient, if the abberant mesenteric circulation remained unrecognized at the time of surgery, and the MA were divided without vascular reconstruction, severe ischemia and subsequent gangrene of large part of the visceral organs would have occurred.

CONCLUSION

This case illustrates the fundamental importance of assessment for vascular anatomy in patients undergoing oncologic abdominal surgery which associates with division of major mesenteric arteries.

Diagnostic accuracy of computed tomography for colon cancer staging: a systematic review

BACKGROUND

Computed Tomography (CT) is a frequently used staging modality for colon cancer patients in clinical practice. Our aim was to systemically review the available literature on diagnostic accuracy of CT for TNM staging of colon cancer.

METHODS

A systematic review of literature was performed. PubMed was searched using MeSH terms with the following search terms: "Tomography, X-Ray Computed" or "Tomography, Spiral Computed" and Colonic Neoplasms. Studies on rectal cancer and studies without separate analyses for the colon were excluded. We identified 779 publications, of which 11 were included for review. Overall and sample-size-weight sensitivity, specificity, accuracy, true-positive, true-negative, false-positive, false-negative, positive and negative predictive values were calculated for T, N and M stages.

RESULTS

In the 11 studies, a total of 753 patients with 759 colon cancers underwent CT for staging. Sample-size-weighted sensitivity, specificity and accuracy for T-staging was 77%, 3% and 67%, respectively; for N-staging 76%, 55% and 69%, respectively; and for M-staging 85%, 98% and 95%, respectively. Additional clinical findings were reported in 59/372 (16%) patients, with 12 having a malignant and 47 a benign origin.

CONCLUSIONS

While accuracy of CT for TN-staging of colon cancer is only reasonable, the real value of CT is its high accuracy to detect distant metastases.

Laparoscopic extraperitoneal rectal cancer surgery: the clinical practice guidelines of the European Association for Endoscopic Surgery (EAES)

BACKGROUND

The laparoscopic approach is increasingly applied in colorectal surgery. Although laparoscopic surgery in colon cancer has been proved to be safe and feasible with equivalent long-term oncological outcome compared to open surgery, safety and long-term oncological outcome of laparoscopic surgery for rectal cancer remain controversial. Laparoscopic rectal cancer surgery might be efficacious, but indications and limitations are not clearly defined. Therefore, the European Association for Endoscopic Surgery (EAES) has developed this clinical practice guideline.

METHODS

An international expert panel was invited to appraise the current literature and to develop evidence-based recommendations. The expert panel constituted for a consensus development conference in May 2010. Thereafter, the recommendations were presented at the annual congress of the EAES in Geneva in June 2010 in a plenary session. A second consensus process (Delphi process) of the recommendations with the explanatory text was necessary due to the changes after the consensus conference.

RESULTS

Laparoscopic surgery for extraperitoneal (mid- and low-) rectal cancer is feasible and widely accepted. The laparoscopic approach must offer the same quality of surgical specimen as in open surgery. Short-term outcomes such as bowel function, surgical-site infections, pain and hospital stay are slightly improved with the laparoscopic approach. Laparoscopic resection of rectal cancer is not inferior to the open in terms of disease-free survival, overall survival or local recurrence. Laparoscopic pelvic dissection may impair genitourinary and sexual function after rectal resection, like in open surgery.

CONCLUSIONS

Laparoscopic surgery for mid- and low-rectal cancer can be recommended under optimal conditions. Still, most level 1 evidence is for colon cancer surgery rather than rectal cancer. Upcoming results from large randomised trials are awaited to strengthen the evidence for improved short-term results and equal long-term results in comparison with the open approach.

Molecular alterations associated with liver metastases development in colorectal cancer patients

Background:

Understanding the molecular biology of colorectal cancer (CRC) provides opportunities for effective personalised patient management. We evaluated whether chromosomal aberrations, mutations in the PI(3)K signalling pathway and the CpG-island methylator phenotype (CIMP) in primary colorectal tumours can predict liver metastases.

Methods:

Formalin-fixed paraffin-embedded material from primary colorectal tumours of three different groups were investigated: patients with CRC without metastases (M0, n=39), patients who were treated with hyperthermal intraperitoneal chemotherapy for CRC metastases confined to the peritoneum (PM, n=46) and those who had isolated hepatic perfusion for CRC metastases confined to the liver (LM, n=48).

Results:

All samples were analysed for DNA copy number changes, PIK3CA, KRAS, BRAF mutations, CIMP and microsatellite instability. The primary CRCs of the LM group had significantly higher frequency of amplified chromosome 20q (P=0.003), significantly fewer mutations in the PI(3)K signalling pathway (P=0.003) and fewer CIMP high tumours (P=0.05). There was a strong inverse correlation between 20q and the PI(3)K pathway mutations.

Conclusion:

The development of CRC liver metastases is associated with amplification of chromosome 20q and not driven by mutations in the PI(3)K signalling pathway.

The value of true axial imaging for CT staging of colonic cancer

OBJECTIVE

To assess the effect of true axial computed tomography on the accuracy of staging of colonic cancers.

METHOD

Fifty consecutive datasets were independently assessed by three radiologists, experienced in colorectal cancer staging. The first read was of standard axial images only. The second read was 6 weeks later and true axial images, through the tumour and perpendicular to its long axis, were included.

RESULTS

The overall accuracy for tumour staging was 56% for reader 1, 48% for reader 2 and 64% for reader 3 for standard axial CT. This improved to 72% (p = 0.012), 66% (p = 0.012) and 80% (p = 0.021) when the true axial images were added. For nodal staging, overall accuracy improved from 56% to 70% (p = 0.065) for reader 1, 58% to 76% (p = 0.012) for reader 2 and 60% to 76% (p = 0.021) for reader 3 between reads.

CONCLUSION

The accuracy of CT staging of colonic tumours is significantly improved by reviewing images reconstructed in a plane perpendicular to the long axis of the tumour. The accuracy achieved by this analysis is similar to that of CT colonography but avoids the extra complexity, additional cost and increased complications.

Accuracy of multidetector computed tomography in identifying poor prognostic factors in colonic cancer

BACKGROUND

Recent neoadjuvant strategies for high-risk colonic tumours have renewed interest in accurate preoperative staging. The aim of this study was to validate prospectively the accuracy of multidetector computed tomography (MDCT) in stratifying patients into good and poor prognostic groups in a multicentre setting.

METHODS

Staging MDCT scans of 84 patients with colonic cancer were reviewed by two independent radiologists and stratified into low-risk (T1/T2 and T3 with extramural tumour depth (EMD) of less than 5 mm) and high-risk (T3 with EMD of at least 5 mm and T4) tumours. Nodal status and extramural venous invasion (EMVI) were also assessed.

RESULTS

The accuracy, sensitivity, specificity and positive predictive value of stratification by CT compared with histological examination was 74 (95 per cent confidence interval 64 to 82), 78 (65 to 87), 67 (49 to 81) and 81 (68 to 89) per cent respectively. Accuracy for detecting malignant lymph nodes and EMVI was 58 and 70 per cent respectively. The agreement for predicting prognostic stratification was moderate (kappa = 0.54).

CONCLUSION

As the ability of CT to identify node status is poor, the depth of tumour invasion beyond the muscularis propria is the most accurate way to identify patients with a poor prognosis who may be suitable for neoadjuvant treatment.

Colorectal cancer

Substantial progress has been made in colorectal cancer in the past decade. Screening, used to identify individuals at an early stage, has improved outcome. There is greater understanding of the genetic basis of inherited colorectal cancer and identification of patients at risk. Optimisation of surgery for patients with localised disease has had a major effect on survival at 5 years and 10 years. For rectal cancer, identification of patients at greatest risk of local failure is important in the selection of patients for preoperative chemoradiation, a strategy proven to improve outcomes in these patients. Stringent postoperative follow-up helps the early identification of potentially radically treatable oligometastatic disease and improves long-term survival. Treatment with adjuvant fluoropyrimidine for colon and rectal cancers further improves survival, more so in stage III than in stage II disease, and oxaliplatin-based combination chemotherapy is now routinely used for stage III disease, although efficacy must be carefully balanced against toxicity. In stage II disease, molecular markers such as microsatellite instability might help select patients for treatment. The integration of targeted treatments with conventional cytotoxic drugs has expanded the treatment of metastatic disease resulting in incremental survival gains. However, biomarker development is essential to aid selection of patients likely to respond to therapy, thereby rationalising treatments and improving outcomes.

Accuracy of colon tumor localization: Computed tomography scanning as a complement to colonoscopy

AIM: To determine the utility of computed tomography (CT) scanning in localizing colon tumors.

METHODS: At a single tertiary care teaching hospital, a retrospective chart review was conducted on patients who underwent surgery for colon malignancies between January 2004 and May 2006. One hundred and four charts containing all of the following data were reviewed: preoperative colonoscopy report, preoperative CT report, surgical operative report, tumor pathology report. The colon was divided into five segments from the cecum to the sigmoid and the location of the lesions was categorized into one of these areas. The tumor location was considered "erroneous" if its location determined during surgery differed from the location determined by colonoscopy or CT.

RESULTS: Over all, tumor location was accurately determined via colonoscopy in 83/104 cases (79.8%) and erroneously in 21/104 (20.2%) of cases. CT scan accurately localized colon tumors in 52/104 (50.0%) of cases, incorrectly localized tumors in 18/104 (17.3%) of cases, and did not detect known tumors in 34/104 (32.7%) of cases. Of the 21 tumors erroneously located by colonoscopy, 11 (52.4%) were accurately localized by CT scan. The average tumor size for all patients in this study was 5.72 (+/- 3.11) cm. The average size of tumors properly located by colonoscopy and CT was 5.39 (+/- 3.34) cm and 6.79 (+/- 3.48) cm, respectively. The average size of the tumors not detected by CT was 3.98 (+/- 1.75) cm.

CONCLUSION: CT scanning may be used in concert with colonoscopy to help localize colon tumors.

Incomplete colonoscopy in patients with occlusive colorectal cancer: usefulness of CT colonography according to tumor location

PURPOSE

We sought to evaluate the clinical usefulness of CT colonography (CTC) after incomplete conventional colonoscopy (CC) for occlusive colorectal cancer (CRC) according to the tumor location.

MATERIALS AND METHODS

Seventy-five patients with occlusive CRC underwent subsequent CTC immediately after incomplete CC. Fifty-nine patients had distal CRC and 16 had proximal colon cancer. Experienced radiologists prospectively analyzed the location, length, and TNM staging of the main tumor. The colorectal polyps in the remaining colorectum and additional extraluminal findings were also recorded. Sixty-seven patients underwent colorectal resection. We retrospectively analyzed the surgical outcome and correlated CTC and CC findings.

RESULTS

The overall accuracies of tumor staging were: T staging, 86%; N staging (nodal positivity), 70% (80%); and intra-abdominal M staging, 94%. Additional colonic polyps were found in 23 patients. Six synchronous carcinomas were detected (9%); three in the proximal colon and three in the distal colon of occlusion. Clinically significant localization errors at CC were noted in 8 patients (12%, 5 proximal colon cancers and 3 distal CRCs) and were corrected by CTC. After CTC, the surgeons modified the initial surgical plan in 11 cases (16%).

CONCLUSION

In occlusive CRC, CTC is not only useful in the evaluation of the proximal bowel, but can also provide surgeons with accurate information about staging and tumor localization. CTC is recommended when endoscopists encounter occlusive CRC, regardless of tumor location.

Value of multi-slice computed tomography in preoperative "one-station-style" examination for colon cancer

AIM: To assess the value of three-phase contrasted multi-slice computed tomography (MSCT) pneumocolon in preoperative examina-tion of colon cancer.

METHODS: Sixty-three patients with colonic cancer underwent plain MSCT pneumocolon and multiphase contrasted MSCT within 1 week before operation. Contrasted MSCT scans were performed using 16-slices CT system (Toshiba aquilion16) 22 s (phaseⅠ), 37-40 s (phaseⅡ) and 60 s (phase Ⅲ) after intravenous administration of contrast medium. Images were then obtained by CT colonography (CTC), X-ray projection (XRP), multi-planar reformation (MPR), surface shadow display (SSD), CT angiography (CTA) in post-procession workstation. The results were comparatively analyzed with the surgical pathology.

RESULTS: Sixty-four cancer lesions were detected on CT images and in surgery. They located in ascending colon (18 lesions), hepatic flexure of colon (2 lesions), transverse colon (4 lesions), splenic flexure of colon (2 lesions), descending colon (6 lesions), sigmoid (20 lesions, of which 5 lesions in the injunction of sigmoid and rectum), and rectum (12 lesions). Extracolonic diseases were found in 16 patients by MSCT or surgery. On multi-phase contrasted CT images, colon caner lesions demonstrated homogeneous or inhomogenous enhancement, and the absolutely increased peaks in CT density were at phase Ⅱ (30 lesions), phase Ⅱ-Ⅲ (17 lesions), phase Ⅲ (13 lesions) and phaseⅠ-Ⅲ (4 lesions). CTA detected blood-supplying artery of 58 cancer lesions (90.6%). The sensitivity, specificity and positive accuracy were 100%, 64.2%, and 92.1% respectively, for pericolonic fat involvement, and 78.5%, 86.7%, and 86.1% respectively, for abdominal metastasis-positive lymph-nodes.

CONCLUSION: MSCT pneumocolon and preoperative three-phase contrasted CT can provide information about tumor location, number, stage, blood-supplying artery and extracolonic diseases.

Preoperative computed tomography staging of nonmetastatic colon cancer predicts outcome: implications for clinical trials

Colon cancer patients routinely undergo preoperative computed tomography (CT) scanning, but local staging is thought to be inaccurate. We aimed to determine if clinical outcome could be predicted from radiological features of the primary tumour. Consecutive patients at one hospital undergoing primary resection for colon cancer during 2000-2004 were included. Patients with visible metastases were excluded. Preoperative CT scans were reviewed independently by two radiologists blinded to histological stage and outcome. Images of the primary tumour were evaluated according to conventional TNM criteria and patients were stratified into 'good' or 'poor' prognosis groups. Comparison was made between prognostic group and actual clinical outcome. Hundred and twenty-six preoperative CT scans were reviewed. T-stage and nodal status was correctly predicted in only 60 and 62%, respectively. However, inter-observer agreement for prognostic group was 79% (kappa=0.59) and 3-year relapse-free survival was 71 and 43% for the CT-predicted 'good' and 'poor' groups, respectively (P<0.0066). This compared favourably with 75 vs 43% for histology-predicted prognostic groups. Computed tomography is a robust method for stratifying patients preoperatively, with similar accuracy to histopathology for predicting outcome. Recognition of poor prognosis tumours preoperatively may permit investigation into the future use of neo-adjuvant therapy in colon cancer.

Update on Colorectal Cancer Imaging

Colorectal cancer remains a leading cancer killer worldwide. The disease is both curable and preventable, and yet the importance of widespread screening is only now starting to be appreciated. This article reviews the variety of diagnostic tests, imaging procedures and endoscopic examinations available to detect colorectal cancer and polyps in their early stage and also presents details on various screening options. The critical role of the radiologist is elaborated on including accurate assessment of the tumor extent within the bowel wall and beyond and the detection of lymph node and distant metastases. Staging with CT, MR imaging, endorectal ultrasound, and positron emission tomography are of paramount importance in determining the most appropriate therapy and the risk of tumor recurrence and overall prognosis.

The Role of Carcinoembryonic Antigen as a Predictor of the Need for Preoperative Computed Tomography in Colon Cancer Patients

A retrospective study of 117 patients with the diagnosis of colon cancer was performed to evaluate the clinical utility of the preoperative computed tomography (CT) scan and to assess the role of carcinoembryonic antigen (CEA) as a predictor of the need for CT scan in colon cancer patients. Forty-nine patients had a CT scan that altered their treatment. One hundred per cent of stage IV patients versus only 26.5 per cent of stage I, II, and III patients had their operative and/or treatment planning altered by the preoperative CT. The sensitivity of CT scan in predicting metastatic disease was 90.3 per cent. All patients with stage IV disease had an abnormal CEA (>3 ng/mL). There was 89.7 per cent of stage IV patients who had a CEA twice that of normal or above. By using a CEA level of 3.1 ng/mL or above as a prerequisite for preoperative tomography, 34 nonmetastatic patients would not have had preoperative CT scans. Using a prerequisite of 6.1 ng/mL or above, 49 nonmetastatic patients would not have had a preoperative CT scan, and 90 per cent of the stage IV patients would have been imaged. We recommend obtaining a preoperative CT scan on those patients with a CEA value twice that of normal or greater.

Gastrointestinal tract malignancies and positron emission tomography: an overview

(18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging is highly accurate in restaging colorectal cancer, esophageal cancer, and gastrointestinal stromal tumors. Overall, it compares favorably with anatomical imaging in the evaluation of tumor recurrence because metabolic abnormalities usually precede a structural change. Initial staging of these malignancies with PET is best used in patients with locally advanced disease who may benefit from curative resection if distant metastases are not found. It also appears to have great potential in predicting histopathologic response to neoadjuvant therapy and in monitoring the success of radiofrequency ablation and (90)Y microspheres radioembolization soon after intervention. FDG-PET can be used in other gastrointestinal malignancies as a prognostic tool and to detect distant disease but its role has not yet been well defined.

The Treatment of Hepatic Metastases in Colorectal Carcinoma

Colorectal carcinoma is the third most common cause of cancer death in the United States, with 135,000 new cases and 55,000 deaths annually. Ultimately, two-thirds (99,000) of all patients with colorectal cancer will develop metastasis to the liver and other organs in their life span, making metastatic colorectal cancer the second leading cause of cancer-related death in North America. The optimal management of these patients has become increasingly complex with the myriad of treatment options that are available. Because the timing of any therapy (surgery, chemotherapy, or others) has become integral to the success of the treatment, a collaborative approach involving multiple specialties is needed for the best patient outcome. Defined clinical and pathologic determinants of outcome have been demonstrated to effect the overall and disease-free survival of patients with metastatic colorectal cancer. Understanding of these determinants remains essential to any treating physician and has lead to significant paradigm shifts in the management of patients with metastatic colorectal cancer.