CT for the evaluation of carcinomas in the colon and rectum

Contribution of Metabolic Parameters and Pericolic Fat Stranding on Preoperative 18F-FDG PET/CT in Predicting Post-operative Histopathology and Outcome in Colorectal Cancer

Purpose

We aimed to investigate the additional value of preoperative PET/CT and reveal relationships between metabolic parameters, pericolic fat stranding finding, postoperative histopathology, and overall survival in colorectal cancer (CRC).

Methods

CRC patients who underwent preoperative PET/CT between January 2017-December 2021 were analyzed. Lymph nodes, organ metastases, and metabolic parameters were evaluated from PET/CT. The pericolic fat stranding was evaluated from CT component. Relationships between these factors and postoperative histopathological findings were statistically analyzed. Survival analyses were performed.

Results

Ninety-one patients (59 males, 32 females) were included in the study. All tumors showed high FDG uptake (mean SUVmax 19.5 ± 9.9). SUVmax of the tumor differed significantly at T3 and T4 stages (p = 0.041). A significant correlation was found between MTV, TLG values and the differentiation degree (p = 0.005, 0.003, respectively). PET/CT predicted the N stage with a high accuracy rate (80%). PET/CT found additional metastases that changed treatment decisions in one-third of patients. A relationship was found between tumor length, surgical margin, lymphovascular invasion and pericolic fat stranding. In multivariate analysis, differentiation degree (HR = 26.1, 95%CI 1.672-408.467), MTV (HR = 0.3, 95%CI 0.071-0.841), TLG (HR = 3.5, 95%CI 1.065-11.193), and lymphovascular invasion (HR = 0.2, 95%CI 0.026-0.853, p = 0.033) were independent factors affecting overall survival.

Conclusion

Preoperative PET/CT contributes to CRC management by detecting additional metastases as well as predicting prognosis and postoperative findings such as T stage, N stage and tumor differentiation. The SUVmax may differentiate between T3 and T4 tumor. Reporting of pericolic fat stranding may contribute to the estimation of lymphatic invasion and positive surgical margin.

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.

Accuracy of Preoperative Local Staging of Primary Colorectal Cancer by Using Computed Tomography: Reappraisal Based on Data Collected at a Highly Organized Cancer Center

Purpose

In patients with colorectal cancer, preoperative staging using various imaging technologies is important for establishing the treatment plan and predicting the prognosis. Although computed tomography (CT) has been used most widely, the versatility of CT accuracy was primarily because of the lack of specialization. In this study, we aimed to identify whether any advancement in abdominal CT accuracy in the prediction of local staging has occurred.

Methods

Between December 2014 and November 2015, patients with colorectal cancer were retrospectively enrolled. All CT findings were retrospectively reported. A total of 285 patients were included, and their retrospectively collected data were retrospectively reviewed, focusing on a comparison between preoperative and postoperative staging.

Results

The overall prediction accuracy of the T stage was 55.1%, with overstaging occurring in 63 (22.1%) and understaging in 65 patients (22.8%). The sensitivity and specificity were 90.0% and 68.4%, respectively. The overall prediction accuracy of the N stage was 54.7%, with overstaging occurring in 89 (31.2%) and understaging in 40 patients (14.1%). The sensitivity and specificity were 71.9% and 63.2%, respectively. The CT accuracies by pathologic stage were 0%, 62.2%, 25.3%, and 81.2% for stages 0 (Tis N0), I, II, and III, respectively.

Conclusion

CT has good sensitivity for detecting colon cancers with tumor invasion beyond the bowel wall. However, detection of nodal involvement using CT is unreliable. In our opinion, abdominal CT alone has limitations in predicting the local staging of colorectal cancer, and additional technologies, such as CT plus positron emission tomography and/or colonography, will improve its accuracy.

Future directions for monitoring treatment response in colorectal cancer

Treatment of advanced colon and rectal cancer has significantly evolved with the introduction of neoadjuvant chemoradiation therapy so much that, along with more effective chemotherapy regimens, surgery has been considered unnecessary among some institutions for select patients. The tumor response to these treatments has also improved and ultimately has been shown to have a direct effect on prognosis. Yet, the best way to monitor that response, whether clinically, radiologically, or with laboratory findings, remains controversial. The authors' aim is to briefly review the options available and, more importantly, examine emerging and future options to assist in monitoring treatment response in cases of locally advanced rectal cancer and metastatic colon cancer.

Colonoscopic high frequency mini-probe ultrasound is more accurate than conventional computed tomography in the local staging of colonic cancer

AIM

Colonoscopic high frequency mini-probe ultrasound was compared prospectively with CT in the local staging of colonic cancer.

METHOD

Consecutive patients undergoing surgical resection for colonic cancer were recruited. Preoperative 64-slice CT staging with multiplanar reconstruction was compared with colonoscopic high frequency mini-probe ultrasound using 12 MHz and 20 MHz probes. The three methods of staging (CT, 12 MHz ultrasound and 20 MHz ultrasound) were compared with the histological stage of the resected specimen. This was done using weighted kappa coefficients where weights of 0.7-0.8 were given to penalize disagreements of one level in either direction and weights of zero were given to penalize disagreements of more than one level in any direction.

RESULTS

In total, 38 patients with colonic cancer were included. They were located in the sigmoid (n = 20), descending (n = 5), ascending (n = 2) and transverse colon (n = 1) and in the caecum (n = 7) and splenic (n = 2) and hepatic (n = 1) flexure. Histopathological assessment revealed seven pT1, four pT2, 25 pT3 and two pT4 cancers. In relation to the pathology the weighted kappa coefficients were 0.36 (SE = 0.14), 0.81 (SE = 0.16) and 0.81 (SE = 0.17) for CT, ultrasound 12 MHz and ultrasound 20 MHz. Histopathologically 15 (39.5%) patients were lymph node positive. The sensitivity, specificity and kappa coefficient for detection of nodal disease for CT were 80%, 47.8% and 0.25 (SE = 0.14) compared with 80%, 82.5% and 0.62 for 12 MHz ultrasound (SD = 0.14) and 23%, 90.5% and 0.15 (SD = 0.13) for 20 MHz ultrasound.

CONCLUSION

Colonoscopic ultrasound is significantly more accurate than CT for T staging of colonic cancers. With respect to nodal status, 12 MHz ultrasound offers superior accuracy to CT or 20 MHz ultrasound.

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.

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.

CT staging of colon cancer

Computer tomography (CT) has been the principal investigation in the staging of colon cancers. The information obtained with routine CT has been limited to identifying the site of the tumour, size of the tumour, infiltration into surrounding structures and metastatic spread. The Foxtrot trial National Cancer Research Institute (NCRI) has been specifically designed to evaluate the efficacy of neoadjuvant treatment in colon cancers by using preoperative chemotherapy with or without an anti-Epidermal Growth Factor Receptor (EGFR) monoclonal antibody to improve outcome in high-risk operable colon cancer. Patients are selected based on their staging CT examination. The criteria for poor prognosis are T4 and T3 tumours with more than 5mm extramural depth. Thus the success of the trial would depend upon the confidence of the radiologist to identify the patients that would receive the neoadjuvant treatment. The aim of this review is to explain the process of identifying high-risk features seen on the staging CT images. This will help to identify a cohort of patients that could truly benefit from neoadjuvant strategies.

Routine preoperative abdominal computed tomography in colon cancer: a utility study

BACKGROUND

There is no proven utility for preoperative scanning of intraperitoneal colonic cancer with computed tomography (CT). A prospective study was conducted where CT was preoperatively incorporated into the management algorithm to ascertain its role in patient treatment.

METHODS

Thoraco-abdominal CT was performed in both the elective and emergency settings in an unselected group of 73 patients referred to a coloproctology unit established over the last 30 months at the Queen Elizabeth Hospital, Barbados. CT and operative findings were compared to determine the influence that the preoperative CT had on surgical decision making.

RESULTS

Unexpected additional pathology was found in 6.8% of patients. Sensitivity for the detection of visceral metastatic disease was 84.6%. Preoperative CT was deemed to be of clinical value in 24.7% of cases and to definitively alter surgical management in 13.7% of patients. These alterations in management included several types of multivisceral resections, the need for ureteric stenting or reimplantation, the utilization of stomas alone and the avoidance of resection in known metastatic disease.

CONCLUSIONS

Preoperative CT of intraperitoneal colonic cancer adds important technical information to the conduct of the surgery and alters therapy in a selected patient group.

Local therapy for rectal cancer: still controversial?

PURPOSE

Many considerations, such as morbidity, sexual and urinary dysfunction, or risk of definitive stoma have led to the increased popularity of local therapy in the therapeutic strategy for rectal cancer. However, its role in curative intent is still controversial with oncologic long-term results lower than those obtained by radical surgery.

METHODS

MEDLINE, EMBASE, LILACS, Abstract books, and reference lists from reviews were searched with English language publications to review the current status of evidence for local therapy in rectal cancer, looking especially at the oncologic results and patient selection. We have focused on the new strategies combining neoadjuvant and adjuvant treatment to explain their place in the management of rectal cancer.

RESULTS AND CONCLUSIONS

The key to potentially curative local treatment for rectal cancer is patient selection by identifying the best candidates with preoperative tumor staging and clinical and pathologic assessment of favorable features. Low-risk T1 is suitable for local excision alone. Limited data suggest that adjuvant chemoradiotherapy may be helpful in patients with unfavorable T1 and T2 lesions, achieving a local recurrence rate<20 percent. However, the efficacy of salvage surgery after local excision is uncertain.

The Economic Impact of 18FDG Positron Emission Tomography in the Surgical Management of Colorectal Cancer with Hepatic Metastases

BACKGROUND

(18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) is recognized as a powerful tool in the management of patients with recurrent and/or metastatic colorectal cancer. The aim of this was was to analyze costs from the payer's perspective, of adding FDG-PET to a computed tomography (CT) scan preoperatively in colorectal cancer patients with resectable hepatic metastases.

METHODS

CT with and without FDG-PET were compared among patients with colorectal cancer in staging for surgical resection of hepatic metastases. Outcomes included uncomplicated surgery, complicated surgery, or death. Extrahepatic disease occurrence rates and diagnostic accuracy of CT and FDG-PET were obtained from published sources. Complication rates and costs for CT, FDG-PET, and surgical procedures were obtained from Healthcare Finance Administration data.

RESULTS

The average expected surgical cost per patient when FDG-PET was used to determine the presence of extrahepatic disease was 16,278 dollars compared to 21,547 dollars for conventional management-a net savings of 5,269 dollars.

CONCLUSIONS

Integration of FDG-PET into the presurgical evaluation of patients with hepatic metastases could substantially reduce overall costs and patients' morbidity. This substantial net saving results from the unique ability of FDG-PET in excluding patients with extrahepatic disease, and avoiding unnecessary surgical expenses.

Should air contrast computed tomography become the first investigation of the colon of frail or elderly patients?

OBJECTIVE

Air contrast computed tomography (ACCT) is an alternative test to barium enema or colonoscopy. We review our experience of this test as the first investigation of frail, elderly patients with lower gastrointestinal symptoms, and record the subsequent clinical course of these patients to evaluate the efficacy of the technique.

PATIENTS AND METHODS

We performed 109 ACCT studies on frail patients aged 70 years or over with lower gastrointestinal symptoms. The findings were correlated with subsequent investigations and surgical findings. Patients with normal scans were followed up in out-patients or by their GP. Average follow up was 17 months.

RESULTS

A good quality complete examination of the colon was achieved in 97% of patients. Of 109 examinations 34 (31%) were reported as normal, 65 (60%) as diverticular disease, nine (8%) as demonstrating a colonic malignancy and one (1%) showed a benign polyp. One sigmoid tumour was missed initially but diagnosed on a repeat ACCT study.

CONCLUSION

ACCT is a reliable, well-tolerated technique in elderly frail patients.

Spiral CT of colon cancer: imaging features and role in management

Colorectal cancer is a common malignancy that results in significant morbidity and mortality. Abdominal computed tomography (CT) is valuable in planning surgery for colon cancer because it can demonstrate regional extension of tumor as well as adenopathy and distant metastases. At CT, colorectal cancer typically appears as a discrete soft-tissue mass that narrows the colonic lumen. Colorectal cancer can also manifest as focal colonic wall thickening and luminal narrowing. Complications of primary colonic malignancies such as obstruction, perforation, and fistula can be readily visualized with CT. At CT, local extension of tumor appears as an extracolic mass or simply as thickening and infiltration of pericolic fat. Extracolic spread is also suggested by loss of fat planes between the colon and adjacent organs. The liver is the predominant organ to be involved with metastases from colorectal cancer. At CT, hepatic metastases usually appear as hypoattenuating masses, which are best visualized during the portal venous phase of liver enhancement. Other common sites of metastases from colon cancer include the lungs, adrenal glands, and bones. Use of CT is critical for identifying recurrences, evaluating anatomic relationships, documenting "normal" postoperative anatomy, and confirming the absence of new lesions during and after therapy.

In search of a dose-response relationship with radiotherapy in the management of recurrent rectal carcinoma in the pelvis: a systematic review

PURPOSE

A systematic review of the literature was undertaken to address the question: "What is the most effective dose fractionation schedule for the relief of symptoms in patients with pelvic recurrence from rectal or colorectal carcinoma?"

METHODS AND MATERIALS

Cancerlit/Medline-computerized databases were searched between the years 1966-1996. Studies that explored the response to radiotherapy in patients with pelvic recurrence from rectal/rectosigmoid carcinoma were included. Factors that may contribute to differences in results were postulated in advance and the variations encountered between articles were presented. Articles with data applicable to recurrent disease only were included in the primary analysis. The effect of including articles that reported outcomes of recurrences with unresectable primaries and residual disease was presented as a sensitivity analysis.

RESULTS

Only retrospective series (level V evidence) were available. The many sources of potential bias inherent in retrospective analyses make the data suitable for hypothesis generation only. Comparison of response was made between "lower" vs. "higher" doses, using 45-50 Gy as the dividing dose, base on the primary analysis. There were no significant differences observable in terms of initial response and the proportion maintaining a response at 6 months, within the range of doses employed. When data from articles that reported outcomes of recurrent disease with primary untreated cancers and postoperative residual disease were included, there was a suggestion for a more favorable response with higher doses. This requires cautious interpretation within the methodological limitations of the data.

CONCLUSION

The optimal dose fractionation schedule for the palliation of pelvic recurrence from rectal carcinoma remains undefined. Well-designed randomized studies, with study arms that are sufficiently diverse biologically to allow the detection of a dose-response relationship if one existed, equipped with suitable symptom control end points, are necessary to provide a clinically relevant answer.

Preoperative and postoperative imaging for colorectal cancer

Management and survival in colorectal cancer are dictated by the extent of the disease at the initial diagnosis. Technological advances over the past 25 years have improved the ability to accurately preoperatively stage these lesions and detect recurrence. This article reviews the focus on the utility of computerized tomography, magnetic resonance, endoscopic ultrasound, and newer imaging methods including PET scan and monoclonal antibodies in the management of colorectal carcinoma.

Computed tomography of the rectosigmoid region

Knowledge of the anatomy and embryology of the rectosigmoid region is useful for the correct interpretation of computed tomography in this region. The appearances and differential diagnoses of some of the common conditions affecting this region are presented and discussed.

Primary tumour staging of gastric and colorectal cancer

Almost 15 years after its introduction, endosonography or endoscopic ultrasonography is an important technique in a wide range of gastrointestinal diseases. Other imaging techniques are CT, MRI and barium examination. There is a general consensus that the most important prognostic factor in gastric and colorectal carcinoma is the presence or absence of lymph node invasion, but malignant fixation of tumour through direct invasion of adjacent tissues also appears to be very important. Non-invasive preoperative assessment of tumour stage based on one or a combination of the above imaging modalities should allow appropriate treatment to be planned in each case.