Villous tumor of the colon and rectum with special reference to roles of p53 and bcl-2 in adenoma-carcinoma sequence

Adenoma-like adenocarcinoma: clinicopathologic characterization of a newly recognized subtype of colorectal carcinoma

The 5th edition of the World Health Organization (WHO) Classification of Tumours (Digestive System) recognizes a new subtype of colorectal adenocarcinoma, called adenoma-like adenocarcinoma. In this study, we sought to determine its clinicopathologic associations and how it is comparable with adenocarcinoma, of no special type (NOS). We retrospectively reviewed all available archival slides of stage I-III colonic adenocarcinoma resection specimens at our institution from 2013 to 2016.Ninety-one cases were classified as adenoma-like adenocarcinoma, and 251 cases were classified as adenocarcinoma, NOS. Of the adenoma-like adenocarcinoma cases, a majority (65 cases, 71%) were composed exclusively of adenoma-like features, designated as pure adenoma-like adenocarcinoma, whereas in the rest, the component of adenoma-like morphology was more than 50% but less than 100%, designated as mixed adenoma-like adenocarcinoma. Compared with adenocarcinoma, NOS, adenoma-like adenocarcinoma cases were significantly associated with the absence of tumor budding (P < 0.001), the absence of an immature/myxoid desmoplastic reaction (P < 0.001), the presence of intraepithelial tumor-infiltrating lymphocytes (P = 0.006), involvement of fewer lymph nodes ( P < 0.001), fewer tumor deposits (P = 0.042), lower pT stage (P = 0.047), lower pN stage (P < 0.001), and consequently the pTNM prognostic group (P < 0.001), as well as better recurrence-free survival (RFS), as per univariate analysis than adenocarcinoma, NOS cases (P = 0.026) but not as per multivariate analysis. However, mixed adenoma-like adenocarcinoma had a worse RFS than pure adenoma-like adenocarcinoma (hazard ratio = 1.639, 95% confidence interval = 0.494-5.437). Our findings not only support the importance of distinguishing this new subtype of colorectal adenocarcinoma but also raise the question whether mixed adenoma-like adenocarcinoma cases should be included in this category, and if so, whether 50% is an appropriate cutoff, as currently defined by the WHO.

Morphology and Molecular Features of Rare Colorectal Carcinoma Histotypes

Several histopathological variants of colorectal carcinoma can be distinguished, some associated with specific molecular profiles. However, in routine practice, ninety/ninety-five percent of all large bowel tumors are diagnosed as conventional adenocarcinoma, even though they are a heterogeneous group including rare histotypes, which are often under-recognized. Indeed, colorectal cancer exhibits differences in incidence, location of tumor, pathogenesis, molecular pathways and outcome depending on histotype. The aim is therefore to review the morphological and molecular features of these rare variants of intestinal carcinomas which may hold the key to differences in prognosis and treatment.

Adenoma-like adenocarcinoma: a subtype of colorectal carcinoma with good prognosis, deceptive appearance on biopsy and frequent KRAS mutation

AIMS

A subset of colorectal carcinomas (CRCs) architecturally and cytologically resembles adenomatous change, making them difficult to diagnose on biopsy. This subset has not been well characterized to date.

METHODS AND RESULTS

For 35 carcinomas with adenomatous-like areas (cytological and surface architectural appearance that would be insufficient to warrant a diagnosis of adenocarcinoma if evaluated on biopsy), we recorded staging information, molecular data, clinical outcome, whether precursor adenoma was present and whether previous biopsy had been diagnosed as malignant. Despite advanced T-category in 23 (66%) tumours, only seven (20%) had nodal metastases, and only five patients (15%) developed distant metastases. Fifteen cases (43%) had been diagnosed as adenoma on biopsy. Twenty-one resections (60%) showed no residual associated adenoma, including nine called adenoma on biopsy. Median follow-up was 44 months. Four patients (12%) died of disease; 22 were alive at last follow-up. KRAS mutation was seen in 14 of 24 (58%) and four of 17 (24%) were microsatellite-unstable. Patients had significantly improved survival compared to a cohort of patients with conventional well-differentiated CRC after controlling for age and stage (P = 0.011).

CONCLUSIONS

Adenoma-like adenocarcinoma is an uncommon variant of CRC with a low rate of metastasis and good prognosis. Biopsy diagnosis of this lesion may be challenging.

Squamous morula formation in colorectal adenoma: Immunohistochemical and molecular analyses

Little is known about the squamous morular component (SMC) in colorectal neoplasms because of its rarity. The aim of the present study is to elucidate the morphological, immunohistochemical and genetic characteristics of SMCs in colorectal adenomas. Five colorectal adenomas having SMCs were resected from five patients endoscopically. On immunohistochemical examination (four cases), all SMCs were positive for cytokeratin 5/6 in their cytoplasm and positive for β-catenin in their cytoplasm and nuclei. A nuclear positivity of p63 was detected in one SMC. All SMCs were negative for p53, chromogranin A, synaptophysin and NCAM. There was no Ki-67 expression in any of the SMCs. We detected none of mutations of β-catenin, KRAS and BRAF by microdissection and polymerase chain reaction-direct sequence in any of the four examined SMCs. SMCs are a rare but problematic finding in colorectal adenomas. Using immunohistochemistry for β-catenin, cytokeratin 5/6, Ki-67, p53, chromogranin A, synaptophysin and NCAM can facilitate the diagnosis of these peculiar cell nests.

Early colorectal carcinomas: CD10 expression, mucin phenotype and submucosal invasion

We analyzed 170 tumors (polypoid, 98; non-polypoid, 72) of early colorectal carcinoma with or without submucosal invasions (Tis and T1 of TNM classification) from 161 patients to evaluate correlations between clinicopathological factors and immunohistochemical expressions of CD10, MUC2, and MUC5AC. The coexistence of adenomatous components was significantly less common in non-polypoid carcinomas (4.2%) than in polypoid carcinomas (66.3%) (P < 0.0001). Non-polypoid carcinomas were smaller in size and tended to infiltrate into the submucosa with higher incidence of lymphatic and venous permeations. CD10 was more frequently expressed in non-polypoid carcinomas (70.8%) than in polypoid carcinomas (51.0%) (P= 0.01). Total carcinomas with high grade atypia showed higher incidence of CD10 expression (60.6%) than those with low grade atypia (28.9%) (P < 0.0001). Carcinomas with low grade atypia exhibited a higher incidence of MUC2 and MUC5AC expression (91.1% and 57.8%, respectively), when compared with carcinomas with high grade atypia (41.6% and 20.0%, respectively) (both, P < 0.0001). In submucosal invasive carcinomas with residual intramucosal carcinoma component (IMCC), CD10 expression in IMCC and submucosal invasive carcinoma component (SMCC) simultaneously exhibited identical positive or negative results, regardless of the polypoid or non-polypoid growth pattern. The CD10 expression may occur in the early stage of carcinogenesis within the mucosa, and these neoplasms may retain CD10 in SMCC, possibly resulting in more advanced stages of stromal invasion and distant metastases. In conclusion, our data suggest that the CD10 expression and mucin phenotypes may be potentially useful markers for estimating biological properties of early colorectal carcinomas.

p53 Nuclear accumulation and Bcl-2 expression in contiguous adenomatous components of colorectal adenocarcinomas predict aggressive tumor behavior

For subsets of colorectal adenocarcinoma (CRC) patients, nuclear accumulation of p53 (p53(nac)) and Bcl-2 expression are prognostic indicators. To understand their role in the progression of CRC we evaluated 90 CRCs and their contiguous adenomatous components (CAdCs) for immunohistochemical expression of these markers. In general, p53(nac) and Bcl-2 expression was significantly increased when comparing normal colonic epithelia to CAdCs and CRCs. Thirteen (14%) CAdCs that demonstrated p53(nac) continued to express p53(nac) in their contiguous CRCs. A similar trend was observed in Bcl-2 expression in that the majority of CAdCs expressing Bcl-2 continued to express it in their matching CRCs (39/44). Patients whose CAdCs and their contiguous CRCs demonstrate p53(nac) had shorter median survival (35.9 months) than those patients whose CAdCs and CRCs did not (80.56 months). However, patients whose CAdCs had p53(nac) and lacked Bcl-2 expression had the lowest median survival (15.74 months) when compared with patients whose CAdCs did not demonstrate p53(nac) but had increased expression of Bcl-2 (71.77 months). These findings suggest that in those adenomas that demonstrate p53(nac) but lack Bcl-2 expression, their contiguous CRCs are more likely to be aggressive as they progress.

Apoptosis and chemo-resistance in colorectal cancer

Systemic chemotherapy plays an integral part in treating advanced colorectal cancer. However 50% of patients respond poorly or have disease progression due to resistance to chemotherapeutic agents. This article reviews the pathways that regulate apoptosis, apoptotic mechanisms through which chemotherapeutic agents mediate their effect and how deregulation of apoptotic proteins may contribute to chemo-resistance. Also discussed are potential therapeutic strategies designed to target these proteins and thereby improve response rates to chemotherapy in colorectal cancer.

Endoscopic trans-anal resection of rectal tumours: critical appraisal of an interdisciplinary approach

OBJECTIVE

Endoscopic trans-anal resection (ETAR) is an accepted technique for treating benign rectal adenomas that relies on technical expertise with the urological resectoscope. We present our experience with ETAR in an interdisciplinary setting combining the decision-making of the colorectal surgeon with the technical skill of the urologist.

METHOD

Assessment of all patients with adenomas and their subsequent care was organized by the colorectal team. Those with carpet-like rectal adenomas were referred to the urologist for ETAR performed using a Storz-Olympus 27/28Ch resectoscope, with roller-ball for haemostasis and glycine for irrigation.

RESULTS

Twenty-four patients (43-93 years, median 71 years; 14 men and 10 women) underwent 51 ETAR procedures from 1999 to 2005, with a median of two (range 1-6) procedures per patient. Complete clearance was achieved on 25 occasions. Two intra-operative extra-peritoneal perforations occurred which were managed conservatively. There were four cases of postoperative haemorrhage, two of which required a repeat procedure to secure haemostasis. Four patients had postoperative pyrexia that settled with oral antibiotics. Mean tumour distance from the anal verge was 7 cm (range 2-12 cm); the mean tumour area was 8 cm(2) (range 3-20 cm(2)); the mean operating time was 34 min (range 15-60 min) and the mean hospital stay was 32 h (range 24-120 h).

CONCLUSION

An interdisciplinary approach to ETAR uses available clinical resources efficiently as the colorectal surgeon does need to acquire the technical skills of endoscopic resection. Our results compare favourably with other published series and this approach can be adopted by any centre where colorectal and urological surgeons work together.

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas: its histopathologic difference between 2 major types

Intraductal papillary mucinous neoplasm (IPMN) is a unique pancreatic neoplasm developing in the ductal system. Two major histologic subtypes have been reported, that is the gastric type and the intestinal type. However, their histopathologic features, especially those of the gastric type, have not been fully described. To evaluate the features of these two types and refine their differences, we analyzed 80 IPMNs including 50 cases of the gastric type and 30 cases of the intestinal type with mucin immunohistochemistry. By defining a main duct-type lesion as predominantly involving the main pancreatic duct with or without branch ducts, and a branch duct-type lesion as exclusively centered on branch ducts or consisting of a collection of small cystic lesions, gastric-type IPMNs were mostly branch duct-type lesions (98%), whereas the intestinal-type IPMNs were usually main duct type (73%). The histologic grade of the intestinal type was generally higher than that of the gastric type. The intestinal type was also characterized by frequent intraluminal nodular growth, and severe atrophy and fibrosis of the surrounding parenchyma with mucous lake formation. In contrast, pyloric glandlike structures at the base of the papillae and pancreatic intraepithelial neoplasia (PanIN)-like complexes were more frequently observed in the gastric type. A significant difference was observed between the gastric type and the intestinal type with regard to all the above features (P<0.05). Seven cases (23%) of the intestinal type were associated with an invasive adenocarcinoma (6 mucinous and 1 ductal), versus only 1 case (2%) of the gastric type (invasive ductal carcinoma). All cases of both gastric and intestinal types expressed MUC5AC; however, high immunolabeling scores for MUC2 were mostly observed in the intestinal type (P<0.05). In conclusion, gastric and intestinal types of IPMNs have distinct histopathologic features and mucin profiles, suggesting that they may follow different biologic pathways.

Advanced colorectal polyps with the molecular and morphological features of serrated polyps and adenomas: concept of a 'fusion' pathway to colorectal cancer

AIM

To establish and explain the pattern of molecular signatures across colorectal polyps.

METHODS AND RESULTS

Thirty-two sessile serrated adenomas (SSA), 10 mixed polyps (MP), 15 traditional serrated adenomas (SA), 49 hyperplastic polyps (HP) and 84 adenomas were assessed for mutation of KRAS and BRAF and aberrant expression of p53. The findings were correlated with loss of expression of O-6-methylguanine DNA methyltransferase (MGMT). KRAS mutation occurred more frequently (26.5%) than BRAF mutation (4.8%) in adenomas (P < 0.001) and particularly in adenomas with villous architecture (50%). Loss of expression of MGMT correlated with KRAS mutation in small tubular adenomas (P < 0.04). BRAF mutation was frequent in HPs (67%) and SSAs (81%), while KRAS mutation was infrequent (4% and 3%, respectively). Of MPs and SAs, 72% had either BRAF or KRAS mutation. Aberrant expression of p53 was uncommon overall, but occurred more frequently in MPs and SAs (12%) than adenomas (1%) (P < 0.04) and there was concordant loss of expression of MGMT.

CONCLUSIONS

Molecular alterations that are characteristic of the serrated pathway and adenoma-carcinoma sequence can co-occur in a minority of advanced colorectal polyps that then show morphological features of both pathways. These lesions account for only 2% of colorectal polyps, but may be relatively aggressive.

Villous adenocarcinoma of the colon and rectum: a clinicopathologic study of 36 cases

Some colorectal adenocarcinomas show villous architecture with morphologic similarities to tubulovillous or villous adenomas. We reviewed 420 consecutive colorectal adenocarcinoma resection specimens and found that 95 tumors (23%) showed areas of villous architecture. Thirty-six tumors (8.6%) in 35 patients showed more than 50% villous architecture and were designated villous adenocarcinomas. Only 42% of the villous adenocarcinomas showed severe atypia and only 44% of the available pre-resection biopsies of these tumors were diagnosed as adenocarcinoma. Epithelial islands in desmoplastic stroma (EIDS) may be helpful in the diagnosis of these tumors. EIDS were found in 97% of the resection specimens for villous adenocarcinomas and none of 62 resection specimens for tubulovillous or villous adenomas. The presence of EIDS showed a 67% sensitivity, 100% specificity, and 100% predictive value in the diagnosis of villous adenocarcinoma in a blinded review of villous tumors. On review of the pre-resection biopsies of villous adenocarcinoma without a final diagnosis of adenocarcinoma, 40% showed EIDS. Clinical follow-up of the 35 patients with villous adenocarcinoma showed that only one died of colorectal adenocarcinoma (median follow-up, 46 months). This sole patient dying of colorectal adenocarcinoma showed a synchronous advanced stage of nonvillous adenocarcinoma at the time of diagnosis. Villous adenocarcinoma is a diagnostically challenging subset of colorectal adenocarcinoma, which appears to be associated with a favorable prognosis. Classifying these tumors as a special type of colorectal cancer may facilitate the development of diagnostic adjuncts and optimal treatment protocols.

Phenotypic alteration in malignant transformation of colonic villous tumours: with special reference to a comparison with tubular tumours

AIMS

To clarify the cellular differentiation of colorectal villous tumours in malignant transformation, compared with that of tubular tumours (tubular adenoma and adenocarcinoma arising in tubular adenoma).

METHODS AND RESULTS

Forty-nine cases of colorectal villous tumours [six cases of low-grade villous adenoma, 21 of high-grade villous adenoma (VA), nine of invasive carcinoma in villous adenoma (CIVA), and 13 of pure villous carcinoma (PVC)] and 46 cases of tubular tumours [14 cases of low-grade and 17 of high-grade tubular adenoma (TA), and 15 cases of carcinoma in tubular adenoma (CITA)] were selected for this study based on their expression patterns of CD10 (small intestinal brush border), MUC2 (intestinal goblet cell), and HGM (gastric foveolar epithelium). HGM was more frequently expressed in the adenomatous components of villous tumours (63%) than in those of tubular tumours (14%) (P < 0.05). CD10 expression of high-grade TAs (47%) and carcinomas arising in TA (60%) was significantly higher than that of villous tumours (0%) (P < 0.05).

CONCLUSIONS

There were significant differences in the phenotypic expression of adenoma and adenocarcinoma between villous and tubular tumours, respectively. Villous tumours have a pathway of malignant transformation different from that of tubular tumours. Because of biological differences, colorectal villous tumours should be distinguished from tubular neoplasia. The analysis of the phenotype of colorectal neoplasms is useful for the evaluation of tumour progression.

Immunohistochemical evaluation of tissue-specific proteolytic enzymes in adenomas containing foci of early carcinoma: correlations with cathepsin D expression and other malignant features

BACKGROUND

Cathepsin D (CD) is an aspartyl lysosomal protease, and the prognostic value of CD expression has been studied in a variety of tumors, however, its role in early adenocarcinomas remains unclear.

AIM OF THE STUDY

We evaluated the expression of CD in a series of colorectal adenomas with severe dysplasia containing foci of early carcinoma and compared the results to several histopathological and immunohistochemical features.

METHODS

Adenomas were obtained by endoscopic polypectomy from 33 patients. Twenty-four of the 33 adenomas contained well-differentiated adenocarcinomas and nine adenomas contained moderately differentiated adenocarcinomas.

RESULTS

Positive CD expressions were observed in 25% of well-differentiated adenocarcinomas and in 66.7% of moderately differentiated adenocarcinomas (p < 0.05). Of the 12 adenocarcinomas with positive CD expression, four had positive CD expression in their adenomas (p < 0.01), 6 showed positive Ki-67 expression in their adenomas (NS), and 10 had positive p53 expression in their adenomas (p < 0.05). No significant association was seen between the level of CD expression and adenoma size.

CONCLUSIONS

The expression of CD in adenocarcinoma correlated significantly with differentiation, and with the levels of CD and p53 expression in the adenomas of the polyp.

Enhanced oxaliplatin-induced apoptosis following antisense Bcl-xl down-regulation is p53 and Bax dependent: Genetic evidence for specificity of the antisense effect

Introduction: Oxaliplatin, licensed for colorectal cancer chemotherapy, damages DNA by generating intrastrand and interstrand cross-links and can induce apoptosis via a Bax-dependent pathway. Bcl-xl, an antiapoptotic Bcl-2 family member, regulates apoptosis and chemoresistance in several cancer models. Bcl-xl expression correlates with invasiveness in primary colorectal cancer. Bcl-xl may therefore represent a therapeutic target in this disease. We used the mismatch repair-deficient HCT116 colorectal cancer cell line (wild-type HCT116) and p53 null, Bax null, or p21/WAF1 null derivatives to identify genetic determinants of the response to oxaliplatin and tested the hypothesis that antisense-mediated Bcl-xl down-regulation would enhance the apoptotic response in a p53- or Bax-dependent manner. Results: At clinically relevant concentrations, oxaliplatin induced p53 and p53-dependent Bax, Bcl-xl, and p21/WAF1 protein accumulation. A minor degree of apoptosis resulted via a p53- and Bax-dependent pathway. The major response was a transient mixed G1 and G2 growth arrest. The G1 arrest was p53 and p21/WAF1 dependent. A 2′-O-ribose methoxyethyl phosphorothioate antisense oligonucleotide reduced Bcl-xl protein expression by ∼90% in HCT116 (Bcl-xl knockdown). Missense controls were inactive. Prior Bcl-xl knockdown enhanced the apoptotic and the global cytotoxic effect of oxaliplatin. The extent of enhancement of apoptosis depended on the integrity of the p53- and Bax-mediated apoptotic pathway, providing genetic evidence that the desired proapoptotic antisense effect is due to specific down-regulation of the Bcl-xl target. Conclusion: The combination of oxaliplatin and Bcl-xl antisense merits testing in models of colorectal cancer in vivo.