ACR Appropriateness Criteria® Staging of Colorectal Cancer: 2021 Update

Preoperative imaging of rectal carcinoma involves accurate assessment of the primary tumor as well as distant metastatic disease. Preoperative imaging of nonrectal colon cancer is most beneficial in identifying distant metastases, regardless of primary T or N stage. Surgical treatment remains the definitive treatment for colon cancer, while organ-sparing approach may be considered in some rectal cancer patients based on imaging obtained before and after neoadjuvant treatment. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Radiologic Management of Lower Gastrointestinal Tract Bleeding: 2021 Update

Diverticulosis remains the commonest cause for acute lower gastrointestinal tract bleeding (GIB). Conservative management is initially sufficient for most patients, followed by elective diagnostic tests. However, if acute lower GIB persists, it can be investigated with colonoscopy, CT angiography (CTA), or red blood cell (RBC) scan. Colonoscopy can identify the site and cause of bleeding and provide effective treatment. CTA is a noninvasive diagnostic tool that is better tolerated by patients, can identify actively bleeding site or a potential bleeding lesion in vast majority of patients. RBC scan can identify intermittent bleeding, and with single-photon emission computed tomography, can more accurately localize it to a small segment of bowel. If patients are hemodynamically unstable, CTA and transcatheter arteriography/embolization can be performed. Colonoscopy can also be considered in these patients if rapid bowel preparation is feasible. Transcatheter arteriography has a low rate of major complications; however, targeted transcatheter embolization is only feasible if extravasation is seen, which is more likely in hemodynamically unstable patients. If bleeding site has been previously localized but the intervention by colonoscopy and transcatheter embolization have failed to achieve hemostasis, surgery may be required. Among patients with obscure (nonlocalized) recurrent bleeding, capsule endoscopy and CT enterography can be considered to identify culprit mucosal lesion(s). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Abstract 1857: Dysregulation of transsulfuration enzymes contribute to malignant transformation in a murine model of colitis-associated carcinogenesis

Introduction: Ulcerative colitis (UC) is a highly morbid, chronic inflammatory disease characterized by mucosal ulceration of the colonic mucosa and is associated with the higher risk of colitis-associated cancer (CAC). The exact mechanism(s) causing UC progression to CAC is currently unknown. The balanced activity of transsulfuration pathway enzymes, cystathionine-gamma-lyase (CSE) and cystathionine-beta-synthase (CBS), and their production of endogenous hydrogen sulfide gas, are critical to maintenance of the colonic homeostasis. CSE activity is suggested to be important for wound healing and mucosal protection. Consistent with this, we have previously showed a decrease CSE expression in human colonic mucosa obtained from patients with chronic UC, compared to normal colonic mucosa by immunocytochemistry. By contrast, increased CBS expression is implicated in the progression of sporadic colorectal carcinoma. However, the role of these enzymes in CAC is unknown. We hypothesize that the dysregulation in CSE/CBS expression and activity is important to the progression from UC to CAC.

Methods: CSE null mice and wild type Sv129/B6 (control) mice were used in azoxymethane-dextran sodium sulfate (AOM-DSS) colon cancer model which mimics human CAC. The disease development was followed up to day 80. Confocal microscopy and Western blot was used to assess the gene expression during cancer development. Size, number, and time interval to tumor formation, as well inflammation were assessed.

Results:

Abrogation of CSE expression using CSE null animals in AOM-DSS model of CAC accelerated the time to tumor development and resulted in an increase in both tumor size (p<0.001) and number (p<0.001) compared to wild-type controls. CBS protein expression was increased within the colonic tumor when compared to the normal margin in AOM-DSS treated animals by Western blot analysis and tissue immunostaining. Interestingly, CAC liver metastases, an exceedingly rare finding in this mouse model, were identified.

Conclusion: Taken together, our human and murine data suggest that dysregulation in the transsulfuration pathway enzymes CSE and CBS expression/activity may be critical contributor to the CAC development in UC and may serve as a potential biomarker for disease progression in the future.

Citation Format: Paul Johnson, Ches’Que M. Phillips, Carl Grim, John R. Zatarain, Aakash H. Gajjar, Suimin Qiu, Rui Wang, Celia Chao, Iryna V. Pinchuk, Mark R. Hellmich. Dysregulation of transsulfuration enzymes contribute to malignant transformation in a murine model of colitis-associated carcinogenesis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1857.