Comparison of malignant potential between serrated adenomas and traditional adenomas

Baseline Characteristics and Longitudinal Outcomes of Traditional Serrated Adenomas: A Cohort Study

BACKGROUND AND AIMS

Traditional serrated adenomas (TSAs) may confer increased risk for colorectal cancer (CRC). Our objective with this study was to examine clinical characteristics and long-term outcomes associated with TSA diagnosis.

METHODS

We conducted a retrospective cohort study of U.S. Veterans ≥18 years of age with ≥1 TSA between 1999 and 2018. Baseline characteristics, colonoscopy findings, and diagnosis of incident and fatal CRC were abstracted. Advanced neoplasia was defined by CRC or adenoma with high-grade dysplasia, villous histology, or size ≥1 cm. Follow-up was through CRC diagnosis, death, or end of study (December 31, 2018).

RESULTS

A total of 853 Veterans with a baseline TSA were identified; 74% were ≥60 years of age, 96% were men, 14% were Black, and 73% were non-Hispanic White. About 64% were current or former smokers. Over 2044 total person-years at follow-up, there were 11 incident CRC cases and 1 CRC death. Cumulative CRC incidence was 1.34% (95% confidence interval [CI], 0.67%-2.68%), and cumulative CRC death was 0.12% (95% CI, 0.00%-0.35%). Among the subset of 378 TSA patients with ≥1 surveillance colonoscopy, 65.1% had high-risk neoplasia on follow-up. CRC incidence among TSA patients was significantly higher than in a comparison cohort of patients with normal baseline colonoscopy at baseline (hazard ratio, 3.70; 95% CI, 1.63-8.41) and similar to a comparison cohort with baseline conventional advanced adenoma (hazard ratio, 0.86; 95% CI, 0.45-1.64).

CONCLUSION

Individuals with TSA have substantial risk for CRC based on their cumulative CRC incidence, as well as significant risk of developing other high-risk neoplasia at follow-up surveillance colonoscopy. These data underscore importance of current recommendations for close colonoscopy surveillance after TSA diagnosis.

Serrated polyps of the colon and rectum: a concise review

"Serrated polyps" is the term used for epithelial lesions of the colon and rectum that have a "sawtooth" pattern on the polyp's surface and crypt epithelium. The so-called serrated pathway describes the progression of sessile serrated adenomas and traditional serrated adenomas to colorectal cancer. Said pathway is well recognized as an alternative mechanism of carcinogenesis and accounts for 15-30% of the cases of colorectal cancer. It also explains a large number of the cases of interval colorectal cancer. Thus, due to their usually aggressive and uncertain behavior, serrated polyps are of the utmost importance in colorectal cancer screening. Our aim was to review the history, current nomenclature, pathophysiology, morphology, treatment, and surveillance of serrated polyps.

Screening of colorectal cancer: present and future

INTRODUCTION

Colorectal cancer (CRC) is the third most common cancer in males and second in females, and the fourth most common cause of cancer death worldwide. Currently, about 60-70% of diagnosed cases in symptomatic patients are detected at an advanced stage of disease. Earlier stage detection through the use of screening strategies would allow for better outcomes in terms of reducing the disease burden. Areas covered: The aim of this paper is to review the current published evidence from literature which assesses the performance and effectiveness of different screening tests for the early detection of CRC. Expert commentary: Adequate screening strategies can reduce CRC incidence and mortality. In the last few decades, several tests have been proposed for CRC screening. To date, there is still insufficient evidence to identify which approach is definitively superior, and no screening strategy for CRC can therefore be defined as universally ideal. The best strategy would be the one that can be economically viable and to which the patient can adhere best to over time. The latest guidelines suggest colonoscopy every 10 years or annual fecal immuno-chemical test (FIT) for people with normal risk, while for individuals with high risk or hereditary syndromes specific recommendations are provided.

The clinical impact of serrated colorectal polyps

Serrated polyps (SPs) of the colorectum pose a novel challenge to practicing gastroenterologists. Previously thought benign and unimportant, there is now compelling evidence that SPs are responsible for a significant percentage of incident colorectal cancer worldwide. In contrast to conventional adenomas, which tend to be slow growing and polypoid, SPs have unique features that undermine current screening and surveillance practices. For example, sessile serrated polyps (SSPs) are flat, predominately right-sided, and thought to have the potential for rapid growth. Moreover, SSPs are subject to wide variations in endoscopic detection and pathologic interpretation. Unfortunately, little is known about the natural history of SPs, and current guidelines are based largely on expert opinion. In this review, we outline the current taxonomy, epidemiology, and management of SPs with an emphasis on the clinical and public health impact of these lesions.

High-risk metachronous polyps are more frequent in patients with traditional serrated adenomas than in patients with conventional adenomas: a multicenter prospective study

BACKGROUND AND AIMS

Although the malignant progression of serrated polyps has been clearly documented, the malignant potential of the traditional serrated adenoma (TSA) subtype has not been established. We compared the prevalence of metachronous polyps in surveillance colonoscopies between patients with TSA and those with conventional adenomas (CAs).

METHODS

Four hundred twenty patients were diagnosed with TSAs by current diagnostic criteria at 10 tertiary care university hospitals in Korea from January 2003 to December 2005; 186 patients who received surveillance colonoscopy after removal of initial polyps were enrolled. During the same time period, 372 age- and sex-matched patients diagnosed with CAs were used as a control group.

RESULTS

TSA patients had a significantly higher recurrence rate of colorectal polyps compared with CA patients (66.1% vs 43.5%, respectively). TSA patients had a greater number (3 vs 2) and larger size (8.6 ± 5.7 vs 6.3 ± 5.2 mm) of recurrent polyps compared with CA patients. TSA patients also had a higher rate of CA (54.8% vs 37.9%), serrated adenoma (14.0% vs. 0.8%), and hyperplastic polyp (33.3% vs. 13.7%) recurrence compared with CA patients. TSA patients had significantly greater odds of having a recurrent high-risk polyp than CA patients (odds ratio, 2.37; 95% confidence interval, 1.55-3.63).

CONCLUSIONS

In comparison with patients with CAs, patients with TSAs have a higher metachronous occurrence rate of all polyp subtypes including CAs, serrated adenomas, and hyperplastic polyps. Moreover, the presence of TSAs is an independent predictor of a high-risk polyp occurrence.

Hyperplastic polyps of the colon and rectum - reclassification, BRAF and KRAS status in index polyps and subsequent colorectal carcinoma

Hyperplastic polyps (HP) of the colon and rectum were previously considered benign. Newer studies have suggested that colorectal HP are different entities. The aim of this study was to reclassify lesions from a 5-year period previously classified as colorectal HP into traditional hyperplastic polyp (THP), sessile serrated lesions (SSL), and other lesions. All patients were confirmed in the Danish National Pathology Database for the occurrence of metachronous polyps/adenomas, colorectal cancer (CRC), and other gastrointestinal malignancies. Molecular pathology of the CRC were characterized and correlated with the index lesion. In total, 591 HP biopsy specimens were obtained from 480 patients. The lesions were reclassified as: 358 THP, 109 SSL, 35 TA, 81 unspecified non-neoplastic lesions, four traditional serrated adenoma, and 4 SSL with cytological dysplasia. Seven patients developed CRC in the follow-up period (1 patient had SSL, 4 had THP, and 2 had unspecified non-neoplastic lesions). Ten patients developed other gastrointestinal malignancies. The patient with SSL as index lesions who developed CRC harbored V600E BRAF mutation in both index lesion and the carcinoma. Sixteen percent of patients with SSL subsequently developed a neoplastic lesion. Further studies are needed to clarify the cancer risk of SSL.

[Serrated lesions of the large bowel]

The 2010 WHO classification identifies a new group of pretumor lesions of the large bowel--serrated masses, which includes hyperplastic polyps (HPs), sessile serrated adenomas/polyps (SSA/P), and traditional serrated adenomas (TSA). Serrated masses are a heterogeneous group characterized by serrated gland lumens and, in most cases, without dysplasia. An enlarged proliferative zone, elongated crypts, and no cytological atypia in addition to a serrated lumen are typical of HPs. SSA/P is characterized by the migration of the proliferative zone to the crypt walls, giving rise to specific architectural disorders, such as expanded and horizontally growing basal gland segments along the lamina muscularis mucosae. TSA is typified by short ectopic crypts that cannot reach the lamina muscularis and by epithelial eosinophilic changes. SSA/P and TSA have peculiar molecular genetic profiles and proven malignant potential.

Clinicopathological observations of colorectal serrated lesions associated with invasive carcinoma and high-grade intraepithelial neoplasm

The aim of this study was to investigate the clinicopathological characteristics of colorectal serrated lesions associated with invasive carcinoma and high-grade intraepithelial neoplasm (HIN), as well as to determine the immunohistochemical expression of MutL homolog 1 (MLH1), MutS homolog 2 (MSH2), K-ras and O⁶-methylguanine-DNA methyltransferase (MGMT). A total of 5,347 cases diagnosed with colorectal polyp or adenoma were included in this study from October 2002 to September 2009. A total of 16 cases of colorectal serrated lesions associated with invasive carcinoma/HIN were screened. These comprised seven cases of traditional serrated adenoma (TSA) associated with invasive carcinoma and HIN, six cases of sessile serrated adenoma (SSA) associated with invasive carcinoma/HIN and three cases of hyperplastic polyp (HP) associated with invasive carcinoma/HIN. TSA associated with invasive carcinoma/HIN predominantly occurred in the rectum with a clearly serrated structure and ectopic crypts. High-grade dysplasia was observed in filiform TSA, which was more prone to carcinogenesis. SSA associated with invasive carcinoma/HIN mainly occurred in the ileocecal junction, with the SSA serrated glands closely located adjacent to the muscularis mucosa and the basal crypt expanded with inverted T- or L-shaped branches. HPs were observed in three cases in the cancer-adjacent tissues with invasive carcinoma, while a HP-SSA/TSA-carcinoma sequence was found in two cases. Immunohistochemistry showed that MGMT expression was significantly different in the serrated lesion tissues compared with that in cancer tissues (P=0.022), control cancer tissues (P=0.002) and normal colorectal epithelial tissues (P=0.003). TSA and SSA may progress to cancer or directly develop into invasive adenocarcinoma. Filiform TSA easily develops into HIN, followed by infiltration. HP may arise from the cancer-adjacent tissues of the invasive carcinoma, which are closely adjacent to the cancer tissues. Further research is needed to investigate the potential direct involvement of HP in carcinogenesis.

Serrated polyps: new classifications highlight clinical importance

AIM

Many lesions previously classified as hyperplastic polyps and therefore thought to be innocuous have been reclassified as sessile serrated adenomas/polyps (SSA/Ps), establishing their place in the serrated pathway and underscoring their malignant potential. The clinical relevance of this new nomenclature is incompletely defined. This study examines the incidence and characteristics of colorectal SSA/Ps and describes other associated colorectal neoplasia.

METHOD

A single institution pathology database was searched for the diagnosis of SSA/Ps between January 2004 and October 2007. SSA/Ps found by colonoscopy were included. Patient demographics, SSA/P characteristics and associated colonoscopic findings were retrospectively recorded.

RESULTS

A total of 585 SSA/Ps were removed during 519 colonoscopies in 483 patients performed by 64 different endoscopists. This represented an overall incidence of SSA/Ps per colonoscopy of 2.1% in the 28,054 colonoscopies performed during the study period. The median SSA/P size was 0.8 cm (range 0.2-4.5) and 188 (69%) were ≥ 1.0 cm. Of the 585 SSA/Ps, 366 (63%) were right-sided, 129 (22%) were in the left colon and 90 (15%) were in the rectum. Also, 439 synchronous polyps of other histology (mainly adenomas and hyperplastic polyps) were found during the same 519 colonoscopies.

CONCLUSION

SSA/Ps are rare lesions found during colonoscopy that may coexist with small hyperplastic polyps. Because SSA/Ps are part of the serrated oncogenic pathway, all, even those appearing to be hyperplastic, should be removed or biopsied for diagnosis. Careful review of historical lesions with application of new definitions may redefine risk for malignancy.

Gastric serrated adenoma polyp treated with endoscopic band ligation (with video)

Serrated adenoma of the stomach has been very rarely reported. A 34-year-old woman underwent upper gastrointestinal endoscopy showing a serrated adenoma polyp at the posterior wall of the junction of the fundus and body of the stomach. The polyp was situated in a technically difficult area to perform a polypectomy with a snare. A banding ligation of the polyp was performed with a pneumoactivated esophageal variceal ligation device. At the follow-up, the base of the polyp was free of adenoma. Beside several other polypectomy techniques, the band ligation technique may be used in removing of the gastric polyps, which is cheap, safe and technically easy to perform.

The clinical significance of serrated polyps

Colorectal cancer (CRC) is a heterogeneous disorder than arises via multiple distinct pathways, such as the serrated pathway, in which serrated polyps (including variants of hyperplastic polyps) are the precursor lesions. Approximately 15-20% of all CRCs arise via the serrated pathway, and these serrated carcinomas are clinically, morphologically, and molecularly distinct from conventional CRCs. The prevention of serrated carcinomas represents an important clinical challenge. Gastroenterologists need to recognize and remove potential precursor lesions and implement a post-polypectomy surveillance program when appropriate. This article focuses on the characteristics and significance of clinically relevant serrated polyps and addresses implications for CRC prevention practices.

[Role of mucinohistochemical analysis in verification of malignant potential of colorectal adenoma]

BACKGROUND/AIM

It is a general opinion that the biggest number of colorectal carcinoma (CRC) develops with the malignant alteration of colorectal adenomas (adenoma carcinoma sequence). Malignant potential of adenoma is in the function of its size, histological structure and the grade of dysplasia. An adequate analysis of colorectal adenomas helps their definition and timely removal, which significantly decreases carcinoma incidence. Mucin analysis can provide results which support the adenoma carcinoma sequence theory. The aim of the study was to present histochemical characteristics of adenomas and emphasize the significance of these analyses for the precise adenoma definition.

METHODS

This prospective study included analysis of 117 colorectal adenomas obtained by transcolonoscopic biopsy or polipectomy in 82 patients. The biopsy samples and the removed polyps were coloured by hematoxilin-eozin (HE) staining and histochemical stainings by Periodic Acid Schiff (AB-PAS) and High Iron Diamine/Alcian blue (HID-AB; pH = 2.5) to prove mucins.

RESULTS

Sulphomucins are more often found in adenomas of the left colon than of the right one (p < 0.001). Sialomucins are more reactive in adenomas of the right colon (p < 0.001). Sulphomucins are more reactive in adenomas of < 10 mm diameter (p < 0.05). The reactivity of all mucins is in negative correlation with the degree of dysplasia (p < 0.001). There is a significant difference in the reactivity of sialomucins in adenomas of the same histological type but different degree of dysplasia (chi2 = 25,743, df = 6, p < 0.001).

CONCLUSION

The difference in the presence of mucins between adenomas of the left and right colons supports the theory of adenoma carcinoma sequence, since adenomas of the right colon are more protected by sialomucins and therefore less malignantly altered, which is consistent with CRC topography. Histochemical analysis of colorectum is significant for more accurate gradation of dysplasia and confirmation of malignant alteration. The negative correlation between the degree of dysplasia and the production of mucin indicates the significance of the degree of dysplasia in malignant potential of colorectal adenomas.

Identification of the methylator (serrated) colorectal cancer phenotype through precursor serrated polyps

PURPOSE

Colorectal cancers arise via cumulative genetic and molecular changes that cause mucosal instability, premalignant polyps, and malignant transformation. Distinct neoplastic pathways characterized by chromosomal instability, genetic mutation, and epigenetic methylation have been described, but their associated precursor polyps have not. This study analyzes characteristics of precursor polyps occurring within different molecular subtypes of sporadic colorectal cancer.

METHODS

Colorectal cancers from a prospectively maintained frozen tissue bank were analyzed for microsatellite stability and promoter methylation, defined by the CpG island methylator phenotype. Patients with tumors meeting the following criteria were included: microsatellite stable and methylator-negative; microsatellite stable and methylator-positive; and microsatellite unstable and methylator-positive. Hereditary cancers were excluded. Patient demographics, colonoscopic and histologic polyp characteristics, operative reports, and pathology reports were reviewed.

RESULTS

One hundred seven patients were included: 65, 20, and 22 patients in each group, respectively. The proportion of patients with synchronous polyps and polyp number, size, and location were similar. However, associated polyp histology varied according to tumor classification. Microsatellite stable tumors, regardless of methylator status, had a greater proportion of adenomas than microsatellite unstable tumors, which had an increased proportion of serrated polyps (P = 0.029).

CONCLUSIONS

Patients with microsatellite unstable colorectal cancers demonstrate an increased serrated polyp-to-adenoma ratio compared with microsatellite stable cancers regardless of methylator status. Loss of microsatellite stability appears to be a key event in serrated polyp and cancer formation. An increased proportion of serrated polyps to adenomas discovered in patients on colonoscopy should arouse suspicion that cancers arising in these patients are probably microsatellite unstable.

Diagnostic value of magnifying endoscopy in early-stage gastrointestinal tumors and their precancerous lesions

With advance in endoscopic technology and its increasing importance in clinical diagnosis, magnifying endoscopy has attracted increasing attention and has been widely used in clinics. At present the new magnifying endoscope is able to clearly demonstrate duct openings of gastrointestinal tract mucosa and microstructural changes, thus enabling discovery and diagnosis of early lesions that are difficult for common endoscope, especially early-stage malignant tumors and precancerous lesions. Recently, magnifying endoscopy in combination with staining or with narrow-band imaging technology facilitates its wider use. This paper reviewed the diagnostic value of magnifying endoscopy in early-stage gastrointestinal tumors and precancerous lesions.