Colon cancer screening update and management of the malignant polyp

Diagnosing colorectal abnormalities using scattering coefficient maps acquired from optical coherence tomography

Optical coherence tomography (OCT) has shown potential in differentiating normal colonic mucosa from neoplasia. In this study of 33 fresh human colon specimens, we report the first use of texture features and computer vision-based imaging features acquired from en face scattering coefficient maps to characterize colorectal tissue. En face scattering coefficient maps were generated automatically using a new fast integral imaging algorithm. From these maps, a gray-level cooccurrence matrix algorithm was used to extract texture features, and a scale-invariant feature transform algorithm was used to derive novel computer vision-based features. In total, 25 features were obtained, and the importance of each feature in diagnosis was evaluated using a random forest model. Two classifiers were assessed on two different classification tasks. A support vector machine model was found to be optimal for distinguishing normal from abnormal tissue, with 94.7% sensitivity and 94.0% specificity, while a random forest model performed optimally in further differentiating abnormal tissues (i.e., cancerous tissue and adenomatous polyp) with 86.9% sensitivity and 85.0% specificity. These results demonstrated the potential of using OCT to aid the diagnosis of human colorectal disease.

Malignant Colorectal Polyp Pathology: Are We Getting Sufficient Information to Make Decisions?

The College of American Pathologists has published guidelines for malignant colorectal polyp pathology reports that list histopathological features that are "core elements" and "optional." Lack of element reporting may result in inaccurate tumor risk stratification.This study aimed to perform a population-based assessment of pathology reporting for T1 colorectal cancers and determine the completeness of reporting for core and optional histopathological elements.This is a retrospective cohort study.This study reviews the pathology reports of endoscopically resected malignant colorectal polyps in Alberta, Canada between 2014 and 2016.Individuals aged 18 years or older with T1 colorectal polyps were selected.Histopathological elements were dichotomized into core and optional. Malignant polyps were classified as high risk or low risk for lymph node metastases and local intraluminal recurrence. Addendum reports were compared with first reports.After applying exclusion criteria, 431 polyps were analyzed. The mean age of patients was 65.5 years; 59.4% were male. Histological grade, deep margin, and lymphovascular invasion were reported in 82.4%, 86.8% and 75.6%; all 3 were reported in only 66.4%. Tumor budding (not in the 2016 guidelines) was reported in 14.4%. One hundred ninety polyps (44.1%) were high risk. Thirty-seven polyps (8.3%) had an addendum report. Following the addendum, 1 polyp was downgraded to low risk, and 9 polyps were upgraded to high risk.The main limitation of the study is its retrospective nature. The decision making surrounding treatment for T1 cancers is complex, and factors other than histopathological tumor features may have been part of treatment decisions.There is a high rate of incomplete reporting of core and optional elements for malignant colorectal polyp pathology reports in Alberta. Several variables used by colorectal surgeons for decision making, such as tumor budding and depth of submucosal invasion, are not considered core elements and are infrequently reported. A pathology review by a second pathologist often results in a change in risk stratification. See Video Abstract at http://links.lww.com/DCR/B98. PATOLOGÍA DEL PÓLIPO COLORRECTAL MALIGNO: ¿ESTAMOS OBTENIENDO INFORMACIÓN SUFICIENTE PARA TOMAR DECISIONES?: El Colegio de Patólogos Americanos publico pautas para informes de patología de pólipos colorrectales malignos que enumeran características histopatológicas como "elementos centrales" y "opcionales". La falta de información elemental puede resultar en una estratificación de riesgo tumoral imprecisa.Valoración basada en una población de los informes de patología para los cánceres colorrectales T1 y determinar la precisión de los informes en cuanto los elementos histopatológicos centrales y opcionales.Estudio de cohorte retrospectivo.Este estudio revisa los informes de patología de pólipos colorrectales malignos resecados endoscópicamente en Alberta, Canadá, entre 2014 y 2016.personas mayores de 18 años con pólipos colorrectales T1.Los elementos histopatológicos se dicotomizaron entre elementales y opcionales. Pólipos malignos se clasificaron como de alto riesgo o bajo riesgo de metástasis en los ganglios linfáticos y recurrencia intraluminal local. Los informes enmendados se compararon con los informes originales.Después de aplicar los criterios de exclusión, se analizaron 431 pólipos. La edad media fue 65.5 años, con 59.4% masculinos. El grado histológico, el margen profundo y la invasión linfovascular se informaron confirmaron en 82.4%, 86.8% y 75.6% respectivamente; las tres características se demostraron en solo 66.4%. Un patrón tumoral en ciernes se reporto en 14.4-una característica que no se usaba en las guías de 2016. Ciento noventa pólipos (44.1%) eran de alto riesgo. Treinta y siete pólipos (8.3%) requirieron de un informe enmendado. Aplicación de los nuevos criterios resulto en que 1 pólipo se redujo a bajo riesgo y 9 pólipos se actualizaron como a alto riesgo.La principal limitación del estudio es el diseño retrospectivo. La toma de decisiones en torno al tratamiento de los cánceres T1 es compleja y otros factores además de las características histopatológicas del tumor pueden haber sido parte de las decisiones terapéuticas.Hay una alta tasa de informes incompletos de elementos centrales y opcionales para informes de patología de pólipos colorrectales malignos en Alberta. Algunas variables utilizadas por los cirujanos colorrectales para la toma de decisiones, como el patrón tumoral en ciernes y la profundidad de la invasión submucosa, no se consideran elementos centrales y se informan con poca frecuencia. Una revisión de patología realizada por un segundo patólogo a menudo resulta en un cambio en la estratificación del riesgo. Consulte Video Resumen en http://links.lww.com/DCR/B98. (Traducción-Dr. Adrian E. Ortega).

The Angular Spectrum of the Scattering Coefficient Map Reveals Subsurface Colorectal Cancer

Colorectal cancer diagnosis currently relies on histological detection of endoluminal neoplasia in biopsy specimens. However, clinical visual endoscopy provides no quantitative subsurface cancer information. In this ex vivo study of nine fresh human colon specimens, we report the first use of quantified subsurface scattering coefficient maps acquired by swept-source optical coherence tomography to reveal subsurface abnormities. We generate subsurface scattering coefficient maps with a novel wavelet-based-curve-fitting method that provides significantly improved accuracy. The angular spectra of scattering coefficient maps of normal tissues exhibit a spatial feature distinct from those of abnormal tissues. An angular spectrum index to quantify the differences between the normal and abnormal tissues is derived, and its strength in revealing subsurface cancer in ex vivo samples is statistically analyzed. The study demonstrates that the angular spectrum of the scattering coefficient map can effectively reveal subsurface colorectal cancer and potentially provide a fast and more accurate diagnosis.

Management of Malignant Adenomas

Most polyps that originate in the colon and rectum are benign. A small subset of polyps will contain a malignancy. Although most malignant adenomas are managed with colonic resection a number can be approached with endoscopic, minimally invasive, and observational techniques. This article reviews the histologic characteristics and adverse risk factors that would portend a poor oncologic outcome and therefore suggest formal colonic resection. Modern endoscopic techniques such as endoscopic mucosal resection and endoscopic submucosal resection are discussed.

Identification and chemoprevention in subjects at moderate risk of colorectal cancer

The risk of developing colorectal cancer (CRC) depends on both genetic factors and lifestyle-related factors. Chemoprevention's true contribution is dependent on lifetime CRC risk. There are clinical situations where chemoprevention for CRC is undoubtedly useful. There are other situations where the risk of CRC seems to be only moderately increased and in these situations, the true contribution of chemoprevention is questionable. A few specific studies assessing the effect of chemopreventive agents in these situations are available. In the present article, we will try to better define these particular situations and discuss the risk quantification and the expected chemoprevention contribution.

Multicentric GISCoR Study "intensive clinical follow-up versus surgical radicalization after complete endoscopic polypectomy of a malignant adenoma" (SEC-GISCoR)

Colorectal cancer screening programs result in an early diagnosis of the disease. In 2007, 250 malignant polyps were identified in Lombardy, out of 1,329 screen-detected colorectal carcinomas. The Italian Group for Colorectal Cancer (GISCoR) promoted the multicentric study "Endoscopic Follow-up versus Surgical Radicalization of Malignant Polyps after Complete Endoscopic Polypectomy" (SEC-GISCoR). The protocol was a multicentric, prospective, observational, non-randomized study. It included patients diagnosed a colorectal malignant adenoma, after complete endoscopic removal. From November 2005 to September 2009, three participating centers enrolled 120 patients with malignant polyps after "complete" endoscopic polypectomy; malignant polyps were classified as "low risk" or "high risk". The study had two arms: "Intensive follow-up" (42 patients: 32 with low-risk and 10 with high-risk polyps) and "Surgical radicalization" (78 patients: 5 with low-risk and 73 with high-risk polyps). Data were collected using an online CRF. Overall, 37/120 polyps (30.8%) were low risk and 83/120 (69.2%) were high risk. 42 out of 120 patients (35%) were enrolled in the "clinical follow-up" arm, while 78/120 (65%) entered the surgery arm. In 15 cases, patients were not enrolled in the correct arm, according to the criteria agreed upon before starting the study. There still is a high incidence (11.5%) of pathological mismatches. No clinical event was reported in 2.9 years of follow-up. In conclusion, some differences emerged in the management of patients with malignant polyps among participating centers (p < 0.001), mismatches can be explained by high surgical risk or patient's choice. Only in 5 cases (4.2%), did data analysis not allow to exactly determine the reason for a choice different from protocol criteria. The availability of new risk factors and the evidence of pathological mismatches confirmed the need for future studies on this issue.