Endoscopic mucosal resection of flat and depressed types of early colorectal cancer

Nuclear beta-catenin expression is closely related to ulcerative growth of colorectal carcinoma

Although most colorectal cancer develops based on the adenoma-adenocarcinoma sequence, morphologically, colorectal cancer is not a homogeneous disease entity. Generally, there are two distinct morphological types: polypoid and ulcerative colorectal tumours. Previous studies have demonstrated that K-ras codon 12 mutations are preferentially associated with polypoid growth of colorectal cancer; however, little is known about the molecular mechanism that determines ulcerative growth of colorectal cancer. beta-catenin complex plays a critical role both in tumorigenesis and morphogenesis. We examined the differential expression of beta-catenin and its related factors among different types of colorectal cancer in order to determine any relationship with gross tumour morphology. Immunohistochemical staining of beta-catenin, E-cadherin and MMP-7 was performed on 51 tumours, including 26 polypoid tumours and 25 ulcerative tumours. Protein truncation tests and single-strand conformational polymorphism for mutation of the adenomatous polyposis coli tumour suppressor gene, as well as single-strand conformational polymorphism for the mutation of beta-catenin exon 3 were also done. Nuclear expression of beta-catenin was observed in 18 out of 25 (72%) cases of ulcerative colorectal cancer and seven out of 26 (26.9%) cases of polypoid colorectal cancer. A significant relationship of nuclear beta-catenin expression with ulcerative colorectal cancer was found (P<0.001). However, this finding was independent of adenomatous polyposis coli tumour suppressor gene mutation and E-cadherin expression. Together with previous data, we propose that different combinations of genetic alterations may underlie different morphological types of colorectal cancer. These findings should be taken into consideration whenever developing a new genetic diagnosis or therapy for colorectal cancer.

Clinicopathological characteristics in large, non-polypoid colorectal adenomas with granule-aggregating appearance

Endoscopically, most large, non-polypoid colorectal adenomas have a granule-aggregating appearance, made up of elevations of small, flat lesions projecting above the surrounding mucosa. In this study we investigated the clinicopathological characteristics in 26 cases of such tumours and proposed the term 'granule-aggregating tumour' (GAT). Patients with GATs (16 men and 10 women) had a mean age of 64.3 years (range, 38-83 years). The mean diameter of the GATs was 28 mm (range, 12-62 mm). Histologically, GATs were diagnosed as tubular (15 cases) or tubulovillous (11 cases) adenomas without submucosal invasion. These tumours had a surface morphology comprised mainly of small, flat elevations or granular structures, measuring 1.2 +/- 0.3 mm in diameter. Of the 26 patients with GATs, 19 (73.1%) were asymptomatic and 11 of these 19 cases (57.9%) were detected by a faecal occult blood test. In nine of the 26 patients (34.6%) GATs were accompanied by colorectal cancers arising at other sites. GATs show typical endoscopic features, often lack symptoms and are frequently accompanied by other cancers in other organs. An awareness of the existence of GATs should assist in the screening, prevention and therapy of colorectal tumours.

Bcl-2 expression and frequency of apoptosis correlate with morphogenesis of colorectal neoplasia

AIM

To investigate whether the expression of apoptosis and cell proliferation related proteins is related to the macroscopic form of colorectal neoplasia.

METHODS

The extent of apoptosis, using the 3' end DNA labelling method, and the immunohistochemical expression of cell proliferation (Ki-67) and apoptosis related proteins (Bcl-2, Bak, and p53) were investigated in 64 colorectal adenomas and 22 early carcinomas extending no further than the upper submucosal region. The specimens were classified into three types of macroscopic form (polypoid, flat, and depressed).

RESULTS

The Ki-67 labelling index and the Bak score did not differ significantly among each macroscopic form. In contrast, the apoptotic index and the Bcl-2 score changed significantly according to the macroscopic forms. Compared with polypoid and flat tumours, depressed tumours had a significantly lower apoptotic index (2.84, 2.28, and 1.44, respectively) and a significantly lower Bcl-2 score (3.18, 2.70, and 1.64, respectively). The proliferation/apoptosis ratio was significantly lower in polypoid tumours than in the other two macroscopic forms. The Bcl-2 score became significantly lower as the tumours flattened or took on a depressed form. Immunohistochemical p53 overexpression did not correlate with the macroscopic forms.

CONCLUSIONS

These results suggest that differences in both Bcl-2 expression and apoptosis may play an important role in the morphogenesis of colorectal neoplasia.

Not infrequent K-ras mutations in depressed-type early colorectal carcinomas larger than 10 mm

The aim of this study was to elucidate whether K-ras (codons 12 and 13) mutations occur in depressed-type early colorectal carcinomas (DECas) larger than 10 mm in size. Thirty-four cases of DECas including 27 larger than 10 mm were examined for K-ras mutations by means of microdissection, PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism), and direct sequencing. Although K-ras mutation was infrequent (1/7, 14%) in small (less than 10 mm) DECas, 16/27 (59%) and 17/27 (63%) of DECas larger than 10 mm revealed codon 12, or either codon 12 or 13 mutations, respectively. None of the evaluated pathological factors except size showed a correlation with K-ras mutation. These data indicate that although K-ras mutation could not be involved in the early stage of the progression of DECas, it might play a role at a later stage when the tumor size is over 10 mm.

Histogenesis and morphogenesis of depressed-type early colorectal carcinoma

The aim of this study was to elucidate the histogenesis and morphogenesis of depressed-type early colorectal carcinomas (DECas). Eighty-seven DECas were selected for examination. The 87 DECas included 23 (26.4%) absolutely depressed (ABS) types (depressed mucosa being thinner than the normal mucosa; histologically true depression), 40 (46.0%) relatively depressed (REL) types (the thickness of the depressed mucosa being the same or greater than that of normal mucosa, with depression being relative compared to marginal elevation) and 24 (27.6%) ulcerated (UL) types (no remnant intramucosal component in the depressed area). The rates of residual adenomatous components were 0/23 (0%) for ABS type and 12/40 (30%) for REL type, indicating that the ABS type was thought to have arisen de novo and the REL type was thought to have arisen de novo and via an adenoma-carcinoma sequence. In 13 of the 23 (56.5%) ABS types, carcinoma was located within the depressed area alone, suggesting that many ABS types show a depression from their initial stage. While 33 of the 40 (82.5%) REL types accompanied by marginal elevation consisted of neoplastic mucosa, in 19 of the 33 (57.6%) cases, the depressed area showed a higher grade of atypia than the area of marginal elevation. This suggested that the depression in the REL type was generated secondarily at the center of a pre-existing, superficially elevated tumor due to progression of its histological grade of atypia. ABS type was speculated to be the precursor of UL type since the two types showed similarity (no statistical significant difference) in percent depression (69.6 vs 64.3%), grade of atypia of carcinoma (52.2 and 79.2% consisted of carcinoma with high-grade atypia alone), and frequency of being accompanied by non-neoplastic reactive marginal elevation (56.5 vs 70.8%).

The advanced adenoma as the primary target of screening

The advanced adenoma bridges benign and malignant states and may be the most valid neoplastic surrogate marker for present and future colorectal cancer risk. We define the advanced adenoma as an adenoma with significant villous features (>25%), size of 1.0 cm or more, high-grade dysplasia, or early invasive cancer. Prevention studies should demonstrate a high efficacy in reducing the number of advanced adenomas. We should use the advanced adenoma in the evaluation of new screening technology, nutritional interventions, and chemoprevention agents because the advanced adenoma is a more desirable target for screening efficacy than is the more uncommon but life-threatening cancer stage or the more common but early, less significant small adenoma stage.

High-frequency probe EUS-assisted endoscopic mucosal resection: a therapeutic strategy for submucosal tumors of the GI tract

BACKGROUND

The aim of this study was to evaluate the efficacy and safety of high-frequency probe EUS (HFPE)-assisted endoscopic mucosal resection in the management of submucosal tumors of the GI tract.

METHODS

HFPE-assisted endoscopic mucosal resection was attempted in 28 patients with submucosal tumors less than 2 cm in diameter. HFPE was performed with a 20-MHz "through-the-scope" probe. Saline solution was injected into the submucosa. After confirming detachment of the lesion from the muscularis propria by repeat HFPE, endoscopic mucosal resection was performed with a lift-and-cut or endoscopic mucosal resection cap technique. Follow-up endoscopy was performed in all patients.

RESULTS

Submucosal tumors from the following areas were included: esophagus 3, stomach 4, duodenum 3, and colon 18. The submucosal tumors were located in the upper third (n = 3), middle third (n = 18), and lower third (n = 7) of the submucosa. Twenty-one submucosal tumors were removed by the lift-and-cut technique and 6 by the cap method. One patient required surgical resection after unsuccessful endoscopic mucosal resection. The origin and depth of penetration of all lesions was accurately depicted by HFPE. Median tumor diameter was 9 mm (range 3-20 mm). Resection was successful and complete in 93% of the cases. There were no immediate postprocedure complications (exact 95% CI [0%, 12.3%]). During a median follow-up of 21.5 months (range 2-74 months) no recurrence was found.

CONCLUSIONS

HFPE-assisted endoscopic mucosal resection is safe and effective for the management of selected submucosal tumors of the GI tract. A management algorithm based on endoscopic and HFPE findings is proposed.

Evaluation of apoptosis as a factor affecting the growth of non-polypoid colorectal adenomas

Some colorectal adenomas show non-polypoid features endoscopically, e.g. nodule-aggregation or lateral spreading. To understand the developmental mechanism of non-polypoid adenomas better, we evaluated apoptosis indices in the upper and lower parts of 26 colorectal adenomas of non-polypoid appearance using TUNEL or single-stranded DNA (ssDNA) immunohistochemical staining. Regression analysis showed an extremely strong positive correlation between the apoptosis index (AI) values generated using each method. The AI of the lower section of lesion (4.54 +/- 1.86) was significantly higher than that of the upper part (1.21 +/- 1.47). In conclusion, ssDNA immunostaining is as useful as the TUNEL method in the evaluation of apoptosis in colorectal adenomas. It seems that vertical growth in non-polypoid adenomas is inhibited by apoptosis allowing horizontal growth to dominate and resulting in the characteristic, laterally spreading morphology.

Angiogenesis at the site of deepest penetration predicts lymph node metastasis of submucosal colorectal cancer

PURPOSE

Intratumor microvessel count has been reported as a useful prognostic factor in patients with cancer of various organs. This study was undertaken to clarify the relation between microvessel count and lymph node metastasis in submucosal colorectal cancer.

METHODS

Microvessel count was estimated in 254 invasive tumors that had been resected from patients with submucosal colorectal cancer. Immunohistochemistry with antibodies against CD34 was performed on archival specimens, and microvessel counts were estimated based on the average count of three fields (original magnification, x400) in the most vascular area at the site of deepest submucosal penetration.

RESULTS

Microvessel count ranged from 10 to 98, with a median of 40. Lesions with high microvessel counts (> or =40) had a significantly higher incidence of lymph node metastasis than those with low microvessel counts (<40; 21.8 percent vs. 6.2 percent). None of the 79 lesions with low microvessel counts and submucosal invasion up to a depth of 1,500 microm had metastasized to the lymph nodes. In multivariate analysis, microvessel count was an independent risk factor for lymph node metastasis in submucosal colorectal cancer (P = 0.0026).

CONCLUSION

Microvessel count at the site of deepest submucosal penetration can be one of the most useful predictors for lymph node metastasis. Analysis that combines microvessel count and depth of submucosal invasion may predict the occurrence of lesions without lymph node metastasis.

Clinicopathologic features and endoscopic treatment of superficially spreading colorectal neoplasms larger than 20 mm

BACKGROUND

A colorectal neoplasm that spreads superficially over the mucosa is known as a laterally spreading tumor. The clinicopathologic features of these large lesions and the efficacy and safety of endoscopic mucosal resection (EMR) were studied retrospectively.

METHODS

Surgically or endoscopically resected laterally spreading tumors larger than 20 mm in diameter were studied. Lesions were divided into 2 macroscopic subtypes: F-type, composed of superficially spreading lesions with a flat and smooth surface, and G-type, composed of superficially spreading aggregates of nodules that form relatively flat, broad-based lesions with granulonodular and uneven surfaces.

RESULTS

Thirty-three lesions were of the F-type and 87 the G-type. G-type (mean +/- SD, 35.3 +/- 11.4 mm) lesions were significantly larger (p < 0.01) than F-type (26.0 +/- 7.2 mm) lesions. F-type lesions had a significantly higher frequency of invasive cancer (27.2%) than G-types (10.3%)(p < 0.05). Of the 120 lesions, 81 (67.5%) were resected endoscopically. Patients with 78 of these lesions were followed postoperatively for 60.8 +/- 20.1 months. The rate of local recurrence of endoscopically treated tumors as determined at colonoscopy was 7.4% (6/78). These lesions were completely resected endoscopically. Distant metastases were not detected. Thirteen (16.0%) patients had local bleeding after EMR that was stopped endoscopically. Microperforation of the colonic wall as a result of EMR was diagnosed in 1 (1.2%) of 81 cases.

CONCLUSIONS

Laterally spreading tumors larger than 20 mm, especially those of the G-type, have a low rate of invasion despite their relatively large size. The F-type lesion has a higher malignant potential than the G-type. EMR is an effective and safe treatment for the large laterally spreading tumor.

Laterally spreading tumor: clinicopathological study in comparison with the depressed type of colorectal tumor

AIM

To evaluate the difference between laterally spreading colorectal tumors (LSTs) with depression and depressed-type colorectal tumors.

METHODS

Sixteen LSTs showing the appearance of non-distinct, gently sloping central depressions were compared clinicopathologically with 14 depressed-type tumors that were larger than 10 mm in size.

RESULTS

The mean size of LSTs with depression was 13.5 +/- 3.4 mm, which was significantly larger than that of the depressed type colorectal tumors (11.2 +/- 1.5 mm). The invasion of the depressed-type colorectal tumors was significantly deeper than that of LSTs with depression, despite the larger size of the LSTs. The surface structures (pit patterns) of both types of tumors were apparently different; the pit patterns of LSTs with depression were almost of the type IIIL pit, while that of the depressed-type tumors were almost of type V pits (P < 0.01). Histologically, LSTs with depression appeared to grow in a superficial replacing manner on the edge of the lesions, while depressed-type tumors grew in an expanding manner.

CONCLUSION

It seems appropriate that these LSTs with depression should be distinguished from depressed-type colorectal tumors and regarded as constituting a new clinical entity.

Prevalence and distinctive biologic features of flat colorectal adenomas in a North American population

BACKGROUND & AIMS

To assess the prevalence of flat and depressed (F&D) colorectal adenomas in the United States, we performed a prospective study of 211 American patients.

METHODS

Dye-assisted colonoscopy was performed in the presence of both an American and a Japanese investigator.

RESULTS

F&D lesions were found in 22.7% of patients, and these were more likely to be adenomatous than polypoid lesions (82% vs. 67%; P = 0.03) and contained more invasive cancer (4.5% vs. 0%; P = 0.04), which also appeared to be at a disproportionately advanced stage. The average size of all F&D advanced lesions (high-grade dysplasia and cancer) was significantly smaller than comparable polypoid lesions (10.75 +/- 2.7 mm vs. 20 +/- 2.9 mm; P < 0.05). F&D adenomas showed significantly stronger fragile histidine triad (FHIT) expression and lower p53 reactivity than similarly sized polypoid adenomas, whereas proliferative and apoptotic indices were similar in both groups.

CONCLUSIONS

We conclude that there is a significant prevalence of colonic F&D colorectal adenomas in this country and that these lesions have significantly different biologic features than polypoid lesions. The clinical and epidemiologic implications of these findings for American patients need to be addressed in further studies.

The recognition and endoscopic treatment of early gastric and colonic cancer

As the prognosis of both gastric and colonic cancer remains poor, the challenge is to detect lesions at an early and treatable stage. The benefit of early detection is not only improved survival, but also that patients may be treated with endoscopic mucosal resection, a low-cost, low-morbidity and low-mortality alternative to surgery. In spite of the increasing use of endoscopy in the West, we are not detecting as many early cancers as in Japan. This chapter will discuss the possible reasons for this discrepancy and give a practical guide to 'Japanese endoscopy techniques'. Finally, we have compiled a comprehensive review of the indications, techniques and complications of endoscopic mucosal resection. Throughout the chapter, controversies have been highlighted to give an insight into the limits of our knowledge and stimulate future research.

Potential new endoscopic techniques for the earlier diagnosis of pre-malignancy

Light interacts with tissue in a variety of ways, including absorption, fluorescence, elastic scattering and Raman scattering. These interactions enable a number of promising technologies for endoscopic diagnosis of pre-malignancy, including chromoscopy; fluorescence, scattering and Raman spectroscopies; and optical coherence tomography. Although still in various stages of technical development and clinical trials, these optical diagnostic techniques are demonstrating strong potential to significantly enhance the clinical endoscopist's ability to detect dysplasia in gastrointestinal mucosae.

Adenomatous polyps develop commonly in the ileal pouch of patients with familial adenomatous polyposis

PURPOSE

The aim of this study was to establish the prevalence of adenomatous polyps in the ileal pouch of patients with familial adenomatous polyposis.

METHOD

Forty-three patients who had an ileal pouch for familial adenomatous polyposis were invited to have a careful endoscopic examination of their pouch, including dye spraying. The number of polyps was recorded, and up to ten were biopsied. In addition, four random biopsy specimens were taken from the proximal and four from the distal pouch.

RESULTS

Thirty-three patients with a median age of 36 (range, 14-63) years who had a pouch (5 Kock and 28 pelvic) for a median of 7 (range, 1-19) years accepted the invitation. Twenty-one patients (64 percent) had endoscopically identified polyps, the number of polyps ranging from 1 to 100 (median, 10) and varying in size from 1 to 3 mm. Fourteen patients (42 percent) had adenomatous polyps and 4 of these also had microadenomas on random biopsies. Nine of the 14 patients with adenomas also had lymphoid polyps. Seven patients had lymphoid polyps only and two of these patients had a microadenoma on random biopsy. Four of 12 patients with no visible polyps had microadenomas in their random biopsies. The presence of adenomatous polyps (Pearson's correlation; P < 0.01) increased with the age of the pouch. In total, 20 of 33 (60 percent) patients had adenomas and or microadenomas.

CONCLUSION

Adenomatous polyps occur frequently in ileal pouches. These findings are of concern, and therefore, regular surveillance seems warranted until the natural history of these adenomatous polyps is determined.

An easy method for the intraluminal administration of peppermint oil before colonoscopy and its effectiveness in reducing colonic spasm

BACKGROUND

Systemic administration of a cholinergic blocking agent or glucagon is used to reduce spasms, but it is inconvenient and sometimes causes side effects. This study is an evaluation of the intracolonic administration of peppermint oil during colonoscopy for the control of colonic spasm.

METHODS

Each patient in the treated group (n = 409) was given approximately 200 mL of the solution (a mixture of 8 mL of peppermint oil and 0.2 mL of Tween 80 per 1 L of water with 0.04% indigo carmine) by using a hand pump attached to the accessory channel of the colonoscope. Changes in patient posture were made to distribute the solution. The patients in the control group (n = 36) were given the solution without peppermint oil.

RESULTS

A satisfactory spasmolytic effect was seen in 88.5% of the treated patients and in 33.3% of those in the control group (p<0.0001). No adverse effect was observed. The mean time to onset was 21.6 +/- 15.0 seconds, and the effect continued for at least 20 minutes. In patients with irritable bowel syndrome, efficacy was significantly lower (p < 0.0001).

CONCLUSIONS

The intraluminal administration of peppermint oil by using a hand pump is a simple, safe, and convenient alternative to the systemic injection of a cholinergic blocking agent or glucagon during colonoscopy.

Cathepsin D expression as a possible predictor of lymph node metastasis in submucosal colorectal cancer

The aim of this study was to clarify the usefulness of cathepsin D expression as a predictor of lymph node metastasis in submucosal colorectal cancer (CRC). Cathepsin D expression was examined immunohistochemically in cancer and stromal cells located at the deepest portion of 254 invasive tumours that had been resected from patients with submucosal CRC. In cancer cells, the expression was classified according to differences in intracellular localisation: polarity positive, apical type (PA); polarity positive, basal type (PB); polarity negative (PN); or no expression (NE). Lesions with PN or NE expression showed a significantly higher incidence of lymph node metastasis than those with PA or PB expression. Alternatively, lesions with positive expression in stromal cells showed a significantly higher incidence of lymph node metastasis than that of those with negative expression. None of the lesions with PA or PB expression and negative expression in stromal cells had metastasised to the lymph node. In conclusion, analysis combining cathepsin D expression in cancer and stromal cells may be a quite useful predictor for lymph node metastasis and may broaden the indications for curative endoscopic treatment of submucosal CRC.

Role of colonoscopy in colorectal cancer

Colorectal cancer (CRC) represents the third most common malignancy throughout the world. Little or no improvement in survival has been effectively achieved in the last 50 years. Extensive epidemiological and genetic data are able to identify more precisely definite risk-groups so screening and early diagnosis can be more frequently accomplished. CRC is best detected by colonoscopy, which allows sampling for histologic diagnosis. Colonoscopy is the gold standard for detection of small and premalignant lesions, although it is not cost-effective for screening average-risk population. Colonoscopic polypectomy and mucosal resection constitute curative treatment for selective cases of invasive CRC. Similarly, alternative trans-colonoscopic treatment can be offered for adequate palliation, thus avoiding surgery.

Endoscopic mucosal resection

Endoscopic mucosal resection (EMR), or mucosectomy technique, developed by Japanese endoscopists consists of resecting flat and polypoid neoplasms of the mucosa by longitudinal section through the submucosa. This technique is relatively simple and carries a low morbidity. It represents an important advance for endoscopists in both technical and cancer areas. Compared with the endoscopic methods of tumor destruction (laser, plasma coagulation), EMR presents the advantage of obtaining a complete specimen for histologic analysis.

Endoscopic mucosal resection. Current concepts

Recent advances in endoscopic mucosal resection of superficial early digestive tract cancers are truly remarkable. The extraordinary long-term outcomes of patients who have been treated with endoscopic mucosal resection have encouraged the widespread practice of endoscopic mucosal resection in Japan. These minimally invasive techniques allow safe and effective treatment of diseases that would otherwise require major surgery. This article provides an overview of endoscopic mucosal resection techniques, their associated outcomes, and other potential applications of endoscopic mucosal resection.

Invasive colon cancer derived from a small superficial depressed cancer: report of a case

A 64-year-old male in May 1997 was diagnosed by colonoscopy and a barium enema examination as having an invasive cancer in the transverse colon. Pathologic study of the resected surgical specimen revealed a well-differentiated adenocarcinoma invading the muscularis propria. He had a colonoscopic examination in 1991 and was diagnosed as having multiple adenomas, which were endoscopically removed. After that he had annual colonoscopy or barium enema examination follow-ups. At endoscopy in February 1994, a superficial depressed cancer 6 mm in diameter had been detected. However, the cancer was not seen again in several endoscopic examinations until one in 1997. Because the location of the lesion detected in 1994 and that of the invasive carcinoma detected in 1997 were identical, it was considered that the superficial depressed cancer developed, 40 months later, to an advanced cancer. Doubling time was calculated as 8.4 months.

Analysis of K-ras codon 12 mutations and p53 overexpression in colorectal nodule-aggregating tumors

BACKGROUND AND AIMS

Morphologically, colorectal nodule-aggregating tumors are quite different from polypoid-type colorectal tumors that develop via the adenoma-carcinoma sequence. Although polypoid-type colorectal tumors are well known to have a high incidence of K-ras gene mutation and p53 overexpression, colorectal nodule-aggregating tumors have not been examined in terms of genetic changes and clinicopathological features. In the present study, therefore, we analysed the clinicopathological features, genetic changes in K-ras codon 12, and p53 overexpression in colorectal nodule-aggregating tumors.

METHODS

A total of 18 colorectal nodule-aggregating tumors were surgically resected and then analysed clinicopathologically. Immunohistochemistry and polymerase chain reaction-single stranded conformational polymorphism were performed to analyse p53 abnormalities in the tumors. K-ras codon 12 mutations were screened out by the polymerase chain reaction-restriction fragment length polymorphism method and analysed by fluorescence direct sequencing.

RESULTS

p53 overexpression was observed in six lesions (33%). p53-overexpressing cells were observed in parts of carcinoma or adenoma showing high-grade atypia. Four of the 10 (40%) samples had a p53 gene mutation. Nine of the 18 (50%) samples had a K-ras codon 12 point mutation. In eight cases (89%), the mutations of the K-ras codon 12 were of the same type: GGT (glycine) to GTT (valine).

CONCLUSIONS

The colorectal nodule-aggregating tumor has distinctive characteristics showing a morphological phenotype of the superficial-type tumors and genotype of the polypoid tumors in terms of K-ras gene mutation and p53 overexpression.

Small flat umbilicated tumors of the colon: radiographic and pathologic findings

OBJECTIVE

We describe the radiographic and pathologic findings of small flat umbilicated tumors of the colon detected on double-contrast barium enema examinations performed in a Western population.

CONCLUSION

Unlike those reported by Japanese authors, the small flat umbilicated tumors of the colon in our patients were usually hyperplastic polyps, previously called "inverted hyperplastic polyps." Nevertheless, colonoscopy with excisional biopsy is warranted for such tumors detected on double-contrast barium enema examinations because of the small possibility that these tumors represent adenoma or even early adenocarcinoma.

Loss of standard type of CD44 expression in invaded area as a good indicator of lymph-node metastasis in colorectal carcinoma

PURPOSE

Recent advances have made possible the treatment of small invasive colorectal cancer by means of polypectomy or endoscopic mucosal resection. CD44 expression in cancer cells was identified as an indicator of lymph-node metastasis, which could be evaluated in specimens removed by colonoscopy.

METHODS

The correlation between lymph-node metastasis and the expression of standard-type CD44 in cancer cells was examined immunohistologically using the invaded cancer cells of 61 tissue samples of superficially invasive colorectal cancer. We defined the above as invasive cancer restricted within the colorectal wall. Of the 61 samples, 31 had submucosal invasion and 30 had muscular invasion.

RESULTS

Standard-type CD44 expression in the area of invasion in cases with lymph-node metastasis was remarkably down-regulated. In 43 cases with no lymph-node metastasis, 36 (83.7 percent) of patients had CD44 expression in invaded cells, whereas only two of 18 cases (11.1 percent) with lymph-node metastasis had expression of standard-type CD44 in the same area (P < 0.0001). A total of 69.6 percent (16/23) of patients with loss of standard-type CD44 expression in invaded sites were found to have positive metastasis in the lymph nodes. These results suggest that standard-type CD44 in invasive colon cancer cells could suppress metastasis to the regional lymph nodes.

CONCLUSION

In cases of invasive colorectal cancer, the loss of standard-type CD44 expression in the invaded area is a sensitive marker for metastasis to the lymph nodes. Further investigation with larger patient groups is required to clarify the reliability of loss of standard-type CD44 expression as an indicator for additional surgery after endoscopic resection of submucosal invasive colorectal carcinoma.

Low frequency of bacteremia after endoscopic mucosal resection

BACKGROUND

Endoscopic mucosal resection has become a popular alternative for the treatment of early-stage neoplasia of the gastrointestinal tract. However, there are still no data on the frequency of bacteremia associated with this form of treatment.

METHODS

We conducted a prospective study of 21 men and 17 women undergoing endoscopic mucosal resection with a cap-fitted panendoscope for upper gastrointestinal lesions. Blood cultures were performed before, 10 minutes after, and 4 hours after the procedure for both aerobic and anaerobic bacteria.

RESULTS

Blood culture at baseline was negative in all the patients. Two of 38 patients (5.3 %) had positive blood culture at 10 minutes after the procedure. The isolated microorganisms were Streptococcus salivarius and Corynebacterium species. All patients had negative blood cultures 4 hours later. None of these 38 patients had any symptoms or signs associated with infection.

CONCLUSIONS

Bacteremia associated with endoscopic mucosal resection is infrequent and transient.

Retrospective radiographic analysis of nonpedunculated colorectal carcinomas with special reference to tumor doubling time and morphological change

OBJECTIVE

Our aim was to characterize the development of nonpedunculated colorectal carcinomas by retrospective radiographic analysis, with special reference to tumor doubling time and morphological change.

METHODS

Eleven colorectal carcinomas, which were observed for >6 months by barium enema examinations, were collected and retrospectively reviewed. There were five early and six advanced carcinomas, including submucosally invasive, superficial depressed carcinomas.

RESULTS

Mean diameter of lesions at initial barium enema examination was 13.5 mm (early, 10.4 mm; advanced, 16.0 mm) and that at final barium enema examination was 30.9 mm (early, 18.2 mm; advanced, 41.5 mm). Initial morphology of the lesions was superficial in three, sessile in seven, and semipedunculated in 1. There was no pedunculated lesion. Macroscopic morphology of the five early carcinomas was superficial depressed (IIc) in two cases, mostly depressed but partly elevated (IIc+IIa) in one case, and superficial elevated with a depressed component (IIa+IIc) in two cases; all of the advanced carcinomas were of the ulcerated type. Mean doubling time was 6.8 months (early, 9.4 months; advanced, 4.7 months). Early carcinomas had significantly longer doubling times than advanced carcinomas (p = 0.017, Wilcoxon's text). The lesions with the longest doubling times were superficial depressed lesions.

CONCLUSIONS

Early carcinomas have longer doubling times than advanced carcinomas. Most nonpedunculated colorectal carcinomas grow without significant morphological changes. Superficial depressed type tumors grow slowly, maintaining their macroscopic morphology.

Flat and depressed colonic neoplasms: a prospective study of 1000 colonoscopies in the UK

BACKGROUND

Flat and depressed colorectal tumours were originally thought to be unique to the Japanese population. Recently there have been reports of flat and depressed lesions in western countries but they have been thought to be uncommon.

METHODS

In this prospective study, 1000 consecutive patients attending for routine colonoscopy were examined for flat or depressed lesions. The examinations were done by one European colonoscopist using methods developed in Japan.

FINDINGS

321 adenomas were found: 202 (63%) were polypoid, 36% (117) were flat and 2 (0.6%) appeared depressed. Most adenomas contained areas of mild or moderate dysplasia but 10% (31) were severely dysplastic. Six Dukes' A adenocarcinomas were identified together with 25 more advanced adenocarcinomas. The likelihood of Dukes' A cancer or severe dysplasia increased from 4% (3/70) in small flat lesions, to 6% (9/154) in small polyps, 16% (8/50) in larger polyps, 29% (14/49) in large flat lesions, and 75% (3/4) in depressed lesions. 54% (20/37) lesions containing severe dysplasia or Dukes' A carcinoma were flat or depressed.

INTERPRETATION

The polyp-carcinoma hypothesis prompts colonoscopists to search only for polypoid lesions when screening for cancer, and many early colorectal neoplasms may therefore be missed. Colonoscopists require training in the recognition of flat and depressed lesions to detect colorectal tumours in the early stages.

[Magnifying colonoscopy in the diagnosis of colorectal carcinoma invading the submucosa in familial adenomatous polyposis]

The development of colonoscopy with image magnification has enable to study the colonic mucosa in detail and to do differential diagnosis between neoplastic and non-neoplastic lesions from the observation of pit patterns. The results are comparable to stereomicroscopy being possible to predict the histologic diagnosis. In a patient with familial adenomatous polyposis magnifying colonoscopy was performed and this method demonstrated a wide variation of benign polypoid lesions and the morphological features of early colorectal cancer. In this patient, the evaluation by image magnification, together with indigo carmin 0.4% chromoscopy, showed a wide variety of lesions in the colon and rectum: laterally spreading tumor in the cecum, with IIIL + IV pits, subpediculate polyp in the transverse colon with approximately 2.0 cm diameter and IV + V pits, flat elevated lesions IIIL type, and in the sigmoid colon IIa + IIc lesion with V type of Kudo's classification were observed. The evaluation of pit patterns of the lesions in the transverse and sigmoid colon has enable to do the endoscopic diagnosis of the lesion with submucosal invasion.

Growth patterns of superficially elevated neoplasia in the large intestine

BACKGROUND

The growth pattern and malignant potential of superficially elevated neoplastic lesions remain controversial. A flat adenoma is classified as a superficially elevated neoplasm that characteristically demonstrates high-grade dysplasia despite its small size. In contrast, a nodule-aggregating (NA) tumor, which consists of multiple small aggregated nodules, can also be classified as superficially elevated neoplasia.

METHODS

In this prospective study, 2720 consecutive patients undergoing total colonoscopy were examined for superficially for elevated lesions. Clinicopathologic characteristics, Ki-ras mutational status, and overexpression of p53 protein were compared in 25 NA tumors and 55 flat adenomas without a central depression (flat tumor).

RESULTS

All flat tumors had a tubular pattern, whereas 21 of 25 NA tumors showed a villotubular or tubulovillous pattern. Ki-ras mutation was observed in 44% of NA tumors but in none of the flat tumors. Overexpression of p53 protein was found in 12% of NA tumors and 7% of flat tumors.

CONCLUSIONS

NA tumors and flat tumors have different clinicopathologic and genetic characteristics, although both types of tumor are classified as superficially elevated lesions.

Early colorectal cancer: flat or depressed type

The present review describes the changes in views about the early forms of colorectal cancers. In 1985, a concept of 'flat adenoma' was born in Japan. At around the same time, depressed type early colorectal cancers started to be reported by Japanese colonoscopists. Neither flat adenomas nor depressed lesions have been frequently reported in Western countries, but increasing numbers of such cases are now described. The problem is that flat adenomas and depressed lesions seem to have been confused by many researchers. The biological aggressiveness of these lesions is quite different. The rate of submucosal invasion is very high in depressed lesions, but fairly low in small flat adenomas. Some adenomas may even look depressed at first, but such lesions should not be mistaken for truly depressed lesions. Ignorance or resistance to the concept may inhibit the detection of flat or depressed lesions. Differences of diagnostic criteria between Japanese and Western pathologists may influence the apparent frequency of mucosal cancers, but not that of invasive carcinomas. Many small adenomas do not grow if followed, but depressed lesions grow rapidly and invade the deeper layers and, as a result, may look elevated as a whole. Many cases in previously published papers suggest that small depressed carcinomas of the large intestine may develop without a precursory stage of an adenomatous polyp. At least two carcinogenic pathways, one through adenomatous polyps and one de novo, should be recognized. In addition, the importance of small depressed cancers should be emphasized.

Efficacy of magnifying endoscopy in the differential diagnosis of neoplastic and non-neoplastic polyps of the large bowel

PURPOSE

We have introduced magnifying colonoscopy into clinical practice and analyzed its diagnostic efficacy, especially regarding the ability to distinguish neoplastic from non-neoplastic polyps.

METHODS

The materials consisted of 923 polyps. After identifying the lesions during normal colonoscopy, a dye was sprayed, and then the zoom apparatus of the colonoscope was used to make a magnified observation at a maximum 100 times magnification. We classified the crypt orifices into six categories and labeled them A to F as follows: A, a medium round appearance; B, an asteroid appearance; C, an elliptic appearance; D, a small, round appearance; E, a cerebriform appearance; F, no apparent structural appearance.

RESULTS

Forty-two of 923 polyps did not reveal any clear images of crypt patterns. The percentage of histologically neoplastic change in the lesions classified as A, B, C, D, E, and F were 10, 15.9, 93.7, 100, 94.8, and 87.5 percent, respectively. When we considered types A and B to represent a crypt pattern of non-neoplastic lesions, and types C, D, E, and F to represent neoplastic lesions, and when the lesions that did not show any clear images were classified as a misjudgment, the diagnostic accuracy of neoplastic lesions (sensitivity) was 92 percent and that of non-neoplastic lesions (specificity) was 73.3 percent. Overall, the diagnostic accuracy in differentiating neoplastic from non-neoplastic lesions was 88.4 percent. Twenty-three neoplastic lesions that were misjudged to be non-neoplastic were histologically adenoma with mild atypia in 22 and adenoma with moderate atypia in 1.

CONCLUSION

Magnifying colonoscopy was considered to be useful in determining the indications for colonoscopic removal.

Prospective observation of small "flat" tumors in the colon through colonoscopy

PURPOSE

No prospective observations of "flat" tumors of the colon have yet been reported. The purpose of this study was to investigate the progression of small flat tumors by prospective observations using colonoscopy.

METHODS

The shapes of flat tumors were classified into three types, including slightly elevated lesions with a flat top (flat-top type), slightly elevated lesions with a wide depression in the center (wide-depressed type), and slightly elevated lesions with a slit-like depression in the center (slit-depressed type). A total of 14 flat tumors of the colon in 13 patients (2 women; median age, 58; range, 46-72 years) were examined in this project. All cases were followed up prospectively using colonoscopy, and all underwent a resection using the submucosal saline injection and snaring technique.

RESULTS

Because two patients were eventually dropped from the follow-up, only 12 lesions were studied. The observation period ranged from 11 to 26 (median, 19) months. At the time the observations started, the diameter of the tumors varied from 2 to 6 (median, 4) mm, and the shapes were flat-top type in five lesions, wide-depressed type in three lesions, and slit-depressed type in four lesions. Of the 12 flat tumors, 8 showed various changes in their shape. However, only two lesions demonstrated an increase in diameter of the tumor from 2 to 4 mm. In the other ten tumors any change in size was less than 2 mm. No lesions were carcinomas according to the final histologic diagnosis, but all were adenomas.

CONCLUSIONS

Flat tumors of the colon did not rapidly progress when they measured approximately 5 mm in diameter. Such flat tumors did tend to change their shapes; however, such changes did not indicate invasion to the submucosal layer.

Frequency of early colorectal cancer in patients undergoing colonoscopy

BACKGROUND

Early colorectal cancer is defined as carcinoma limited to the mucosa or submucosa. Up to 20 per cent of all colorectal cancers treated in some Japanese institutions are early cancers. These cancers are sometimes flat or depressed, and may be less than 1 cm in diameter. The aim of this study was to identify the frequency and morphology of early colonic cancers detected at colonoscopy by a surgeon aware of and looking for such lesions.

METHODS

A review was made of all colonoscopies performed by or under the supervision of a single endoscopist between 1990 and 1998. Follow-up and outcome of all patients with early colorectal cancer was undertaken.

RESULTS

Ninety-five invasive colorectal cancers were identified from 2198 colonoscopies. Eighteen were early colorectal cancers (T1). Macroscopically these were flat (nine tumours), villous (four) and pedunculated (five). Two patients had lymph node metastasis. The median size of flat cancers was 20 (range 9-30) mm. Median follow-up was 3 years. One patient had local recurrence, and another, whose early cancer was metachronous, died from metastatic cancer.

CONCLUSION

This study identified early colonic cancer with similar frequency and morphology to that reported by the Japanese. Colonoscopy should be considered as the investigation of choice for patients with large bowel symptoms.