Fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography for the detection of proximal synchronous lesions in patients with obstructive 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.

Detection methods of synchronous colorectal lesions in proximal colon for patients with obstructive colorectal cancer: a literature review

INTRODUCTION

Colorectal cancer holds a high morbidity and mortality rate. As a common method for colorectal cancer detection, colonoscopy has difficulty in passing through the malignant stenosis in patients with obstructive colorectal cancer, which results in incomplete detection and missed diagnosis. The missed synchronous lesions increase the risk of metachronous cancer. Therefore, detecting proximal synchronous lesions in patients with obstructive colorectal cancer should be appreciated before operation.

AREA COVERED

This review evaluates related literature, aiming at providing clinicians with more ideas and attention for detecting proximal synchronous lesions in patients with obstructive colorectal cancer.

EXPERT OPINION

In patients with obstructive colorectal cancer, missed diagnosis of lesions proximal to the obstruction may lead to metachronous colorectal cancer. Except for preoperative colonoscopy which is difficult to pass through malignant stenosis, other methods that can evaluate proximal colon segment are critical. This article introduced several preoperative, intraoperative and postoperative measures for synchronous lesions detection. The choice of methods should base on patients' conditions, aiming at a high diagnostic yield and low risk. Early detection and resection of synchronous lesions in the proximal section of malignant obstruction are expected to minimize the risk of metachronous colorectal cancer and even effect follow-up treatment strategy, which deserves the attention of clinicians.

Implication of FDG-PET/CT without synchronous colonic lesion in patients with stenotic left-sided colorectal cancer

Although 18-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) is useful for detecting synchronous colorectal cancer (CRC) in stenotic CRC, long-term outcomes of patients without synchronous FDG-avid lesions are not well reported. We investigated postoperative colonoscopy results in patients with left-sided stenosing CRC without synchronous FDG-avid lesions. In this retrospective review, 754 patients with left-sided CRC without synchronous FDG-avid lesions on preoperative 18F-FDG PET/CT were divided into two groups based on the completeness of preoperative colonoscopy. Propensity score matching was performed to balance baseline characteristics. Results of postoperative colonoscopy were compared in both the unmatched and matched cohorts. At 1 and 5 years after surgery, the cumulative risk of advanced adenoma (AA) or carcinoma (CA) in all patients, risk of CA, and additional surgical risk were 1.8% and 10.1%, 0.1% and 0.4%, and 0% and 0.5%, respectively. In both cohorts, the AA risk was significantly higher in the incomplete colonoscopy group. However, the risk of CA showed no between-group difference in the matched cohort. Additional surgical risk did not differ between the two groups. Thus, the finding of negative FDG-avid lesions in the proximal colon in addition to the target CRC ensures the absence of additional lesions warranting surgical plan changes.

Ultrathin colonoscopy can improve complete preoperative colonoscopy for stenotic colorectal cancer: Prospective observational study

OBJECTIVES

Preoperative colonoscopy is often incomplete for stenotic colorectal cancers (CRC). This prospective observational study aimed to evaluate the ability of an ultrathin colonoscope (UTC) to inspect the whole colon by passing through the stenotic CRC.

METHODS

All patients who underwent preoperative colonoscopy for stenotic CRCs at Shizuoka Cancer Center were examined for eligibility. If a standard colonoscope (PCF-H290ZI) could not pass because of a stenosis, the patients were recruited. All of the eligible patients were prospectively enrolled when informed consent could be obtained, and complete colonoscopy was attempted again using an UTC (PCF-PQ260L). Patients with stent placement and those requiring right hemicolectomy were not recruited. Primary endpoints were pass-through and cecal intubation rates. The detected synchronous neoplasias (adenomas and cancers) and their pathological findings after resection were evaluated.

RESULTS

A total of 100 patients were enrolled between September 2017 and February 2019. The mean age was 65.6 ± 10.8 years, and 59% were male. The pass-through and cecal intubation rates were 67% (67/100) and 58% (58/100), respectively. Synchronous lesions located proximal to the stenoses were detected in 65.5% (38/58) of the complete colonoscopies, with a total of 86 lesions, including 18 advanced neoplasias with three invasive cancers.

CONCLUSION

When standard colonoscopy cannot pass through stenotic CRC, ultrathin colonoscopy can be considered as an option to inspect the whole colon proximal to the stenosis because treatment strategy can potentially be changed by detecting synchronous neoplasias proximal to the stenosis before surgery. (UMIN000028505).

PET/CT Integrated With CT Colonography in Preoperative Obstructive Colorectal Cancer by Incomplete Optical Colonoscopy: A Prospective Study

AIM

The aim of this study was to evaluate if integrating whole-body PET/CT with CT colonography (PET/CTC) improves the preoperative diagnosis of obstructive colorectal cancer (CRC).

METHODS

We prospectively included 47 consecutive patients (18 women and 29 men; mean age, 71 ± 14 years) suspected of having CRC by optical colonoscopy, which was not completed due to obstructive masses. To perform PET/CTC, a small caliber Foley catheter was inserted to distend the colon with CO2 insufflations. Polyps measuring 10 mm or larger were considered as high risk of malignancy. All findings were histologically confirmed.

RESULTS

Colorectal cancer was localized in the sigmoid (n = 21), rectum (n = 7), rectosigmoid junction (n = 5), ascending (n = 7), descending (n = 5), and transverse (n = 2) colon. All tumors showed FDG uptake (mean ± SD SUVmax, 20.02 ± 9.9) including one synchronic tumor (SUVmax, 10.46). Forty-seven polyps were histologically confirmed as smaller than 10 mm (n = 35) and 10 mm or larger (n = 12). All 12 polyps 10 mm or larger showed FDG uptake (SUVmax range, 3.08-19.5), but only one smaller than 10 mm could be identified by PET. Pathological lymph nodes were diagnosed in 17/47 cases after surgical removal with a sensitivity and specificity for CTC and PET/CTC of 71% and 97% and 59% and 100%, respectively. Liver metastases were confirmed in 9 patients and in 4/9 along with lung metastases (n = 2) or implants (n = 2), showing a sensitivity and specificity for CTC of 89% and 100% and both 100% for PET/CTC.

CONCLUSIONS

PET/CTC is a reliable technique for staging CRC and diagnosing synchronous tumors. In this series, PET/CTC was not able to identify small polyps but showed potential use for ruling out 10 mm or larger polyps at high risk of malignancy.

Efficacy of 18-fluoro deoxy glucose-positron emission tomography computed tomography for the detection of colonic neoplasia proximal to obstructing colorectal cancer

Identification of secondary colonic neoplasia proximal to obstructing colorectal cancer is essential for determining the range of colorectal resection.We examined the accuracy of 18-fluoro deoxy glucose-positron emission tomography (FDG-PET) for detection of colonic neoplasia.We recruited patients with obstructing colorectal cancer from our registry. Preoperative FDG-PET was performed, and the detection rate for colonic neoplasia was estimated. Preoperative colonoscopy or postoperative colonoscopy within a year after operation was employed as the indexed standard.Ninety-three patients were included in this study. Colonic neoplasia proximal to obstruction was confirmed in 83 cases. The sensitivity and positive predictive value of FDG-PET were 25.3% and 77.8%, respectively. The sensitivity was higher in larger lesions (3.2% for <5 mm, 29.4% for 6-10 mm, 45.5% for 11-20 mm, and 71.4% for >21 mm) and in higher pathological grade lesions (14.6% for low-grade adenoma, 38.5% for high-grade adenoma, 66.7% for carcinoma in situ, and 100% for invasive carcinoma). The round shape in PET images was a predictor for neoplasia, with an area under the curve of 0.75293 at an aspect ratio of 1.70.FDG-PET should be used as a screening modality for invasive colorectal cancer (CRC) proximal to obstructing colorectal cancer.