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

Correlation of lifting versus non-lifting and microscopic depth of invasion in early colorectal cancer

BACKGROUND

The non-lifting sign is considered a contraindication to endoscopic resection. Our objective was to investigate whether lifting or nonlifting of a lesion is determined by the volume of normal submucosal tissue.

METHODS

We measured the thickness of the submucosa and examined the relation between submucosal invasion and lesion elevation induced by submucosal injection in 60 patients with colorectal cancer with evidence of submucosal invasion. Extent of tumor elevation was classified into two groups: A, lifting; B, non-lifting. Submucosal invasion was classified as sm1, sm2, or sm3. The distance between the carcinoma and the line of resection and that between the carcinoma and the muscularis propria were measured.

RESULTS

Of 31 sm1 lesions, 29 (93.5%) were group A. All 6 sm3 lesions were group B. All lesions in group A had a value for the distance between carcinoma and muscularis propria of more than 1000 microm. Group B lesions with sm3 invasion had distances of only 105 to 750 microm.

CONCLUSION

Lesions classified as sm3 do not elevate in response to submucosal injection, and lesions that become elevated on injection can be resected endoscopically because they are sm1 or sm2 and have a thickness of normal submucosa of more than 1000 microm.

Cell kinetics, p53 and bcl-2 expression, and c-Ki-ras mutations in flat-elevated tubulovillous adenomas and adenocarcinomas of the colorectum: comparison with polypoid lesions

BACKGROUND

Flat(-elevated) tubulovillous adenomas and adenocarcinomas of the colorectum constitute a specific type of neoplasm with superficial spreading growth. To establish their characteristics, a comparative investigation of a series of tumors was performed.

METHODS

A total of 56 flat tubulovillous tumors (39 adenomas, 17 invasive carcinomas) and 154 polypoid tubular or villous tumors (77 adenomas, 77 invasive carcinomas) were comparatively assessed for cell kinetics and molecular alterations.

RESULTS

Ki-67 labeling and p53 expression for both types of tumors increased along with degree of dysplasia or invasion, whereas bcl-2 expression showed an inverse decrease. However, apoptotic activity was invariably low in the flat tubulovillous tumors, as compared with the polypoid tumors, in which increase was apparent with tumor progression. The flat tubulovillous tumors also showed a higher frequency of c-Ki-ras mutations (92.9%) than the polypoid tubular tumors (40.0%).

CONCLUSIONS

The flat tubulovillous tumor can be considered a distinct entity, with characteristics different from the polypoid counterpart.

Fluorescent tissue site-selective lanthanide chelate, Tb-PCTMB for enhanced imaging of cancer

In-vivo and in-vitro investigations indicate that a newly developed polyazamacrocyclic chelate of Tb(III) has superior properties for use as an abnormal tissue marker. In addition to tissue selectivity, this molecule is unique because of its low toxicity, attractive fluorescent properties, rapid pharmokinetics, and relatively high water solubility. The complex Tb-3,6,9-tris(methylene phosphonic acid n-butyl ester)-3,6,9,15-tetraazabicyclo[9.3.1]-pentadeca-1(15),11,13 -triene (Tb-PCTMB) has also been shown to exhibit strongly shifted emission (delta lambda--280 nm), moving the detection frequency away from autofluorescence backgrounds, and good quantum efficiencies (phi = 0.51), providing high brightness. Fluorescence imaging was used to quantify Tb-PCTMB at the picomolar level in tissues and to show the significant difference in affinity for the chelate by adenocarcinoma cells HT-29 versus normal epithelial cells (IEC-6). Topical application, or lavage introduction, under endoscopy was used to instill a millimolar aqueous solution of Tb-PCTMB into a dimethylhydrizene-treated Sprague Dawley rat large intestine containing a suspect growth. Subsequent in vitro fluorescence detection and standard histological evaluation confirmed enhanced uptake by adenocarcinoma tissue. Semiquantitative signal interrogation was employed to show the potential for using Tb-PCTMB as a contrast enhancement marker for disease detection.

Histologic and immunohistochemical analysis of early submucosal invasive carcinoma of the colon and rectum

To investigate the development and progression of colorectal carcinoma, submucosal invasive carcinoma (SMC) with residual intramucosal neoplasm was studied histopathologically. Intramucosal neoplasm was confirmed by immunohistochemical staining against anti-alpha-smooth muscle actin antibody. Submucosal invasive carcinoma was classified into polypoid growth-type carcinoma (PGC) and non-polypoid growth-type carcinoma (NPGC), depending on the presence of intramucosal tumor proliferation. Tumors were > 15 mm in size in 78.2% of the PGC lesions studied, but the degree of submucosal invasion was minimal (invasion of the upper 500 microm of the submucosal layer) in 52.9% of the PGC lesions. Conversely, 64.4% of NPGC lesions were 15 mm in size and the degree of submucosal invasion was moderate or severe (involving the middle and deeper layer of the submucosa) for 72.9% of NPGC. In other words, lesions of NPGC were significantly smaller in size but showed deeper infiltration than PGC lesions. Furthermore, PGC was derived from intramucosal polypoid carcinoma (including carcinoma with adenoma) and was morphologically identical to polyp cancer as reported previously. However, NPGC was derived from the flat and/or depressed type of intramucosal carcinoma classified not as polyp type, but as the superficial type. Typical NPGC was, therefore, also of the superficial type. In addition, approximately 25% of PGC lesions were identified as having an adenoma-carcinoma sequence. There was no coexistence with adenoma in the NPGC lesions, suggesting de novo development. When the degree of histologic atypia in the two types of intramucosal carcinoma was compared, 74.7% of PGC lesions showed low-grade carcinoma, regardless of tumor size, while 62.7% of NPGC lesions showed high-grade carcinoma in the intramucosal lesion. Approximately 25% of carcinomas with low-grade atypia were positive for p53 (as were the high-grade lesions), but it was not expressed in the adenoma. Therefore, tumor development and the degree of invasion differed significantly between the two types of carcinoma.

Clinicopathological features of superficial depressed-type colorectal neoplastic lesions

OBJECTIVE

We performed this study to analyze the endoscopic findings, dissecting microscopic features, and p53 immunostaining in superficial depressed-type (depressed) colorectal neoplastic lesions.

METHODS

Dissecting stereomicroscopy was used to ascertain the size and pit pattern of lesions removed by endoscopic snare polypectomy. Immunohistochemical staining of p53 was performed with an antigen retrieval system using a monoclonal antibody to p53.

RESULTS

All depressed neoplastic lesions (submucosal carcinoma, n = 6; high-grade dysplasia, n = 14; and adenoma, n = 30) were small (< 1 cm in diameter) and were detected as a depression with or without a marginal elevation on colonoscopic examination. In the dissecting microscopic study, submucosal carcinomas and lesions of high-grade dysplasia almost exclusively showed irregular small pits, with the exception of four malignant lesions with moderate submucosal invasion in which the pit structure was absent. In contrast, adenomas had either regular small (29/30 lesions) or oval pits (1/30 lesions). Rates of p53 positivity were 100%, 64%, and 7% in depressed submucosal carcinomas, lesions of high-grade dysplasia, and adenomas, respectively, thus the prevalence of p53 positivity was significantly higher in the former two groups than in the adenoma group.

CONCLUSIONS

The high frequency of invasive carcinoma and high-grade dysplasia found in depressed colorectal neoplastic tumors, despite their small size, indicates that these lesions may be a subtype of colorectal tumor with more aggressive malignant potential at an earlier stage.

Histopathologic characteristics of advanced colorectal cancer smaller than 2 cm in size

PURPOSE

Screening for colorectal cancer results in an increased incidence of early detection and decreased mortality. Although small colorectal cancer with deep invasion or lymph node metastasis is sometimes encountered, there is no comprehensive study evaluating the histopathologic features of such tumours. The aim of this study was to clarify the characteristics of advanced colorectal cancer <2 cm in size.

METHODS

Using a series of 317 patients who underwent surgery for colorectal cancer, pathologic features were compared among small advanced cancers <2 cm invading the muscularis propria or subserosa (T2, T3) or involving the lymph nodes (N1, N2) (n = 22), small early cancers <2 cm invading only the mucosa or submucosa (T1) without lymph node metastasis (N0) (n = 24), and ordinary advanced cancers> 2 cm (n = 271).

RESULTS

Small advanced cancers were clearly different from small early cancers in gross appearance, histological type, frequency of serosal invasion (18% vs 0%, P < 0.05), lymph node metastasis (36% vs 0%, P < 0.01), and concomitant adenomatous component (17% vs 48%, P < 0.05). Small advanced cancers, when compared with ordinary advanced cancers, were characterized by the grossly superficial type (14% vs 1%, P < 0.01) and absence of serosal invasion (82% vs 14%, P < 0.01) However, the two groups were not significantly different with regard to the frequency of lymph node metastasis (36% vs 53%), liver metastasis (5% vs 15%), and stage of the disease (Dukes' A and B; 64% vs 45%).

CONCLUSION

The results indicate that colorectal cancers, once they invade beyond the submucosa, have the same metastatic potential, irrespective of tumour size. The low frequency of concomitant adenoma implies de novo carcinogenesis of the small advanced cancers.

Solitary rectal ulcer syndrome accompanied by submucosal invasive carcinoma

We report a case of carcinoma in solitary rectal ulcer syndrome. The diagnosis was made by colonoscopic appearance and biopsy. A tumor measuring 0.9 x 0.6 cm was found in a resected solitary rectal ulcer. The lesion exhibited typical histological features of solitary rectal ulcer syndrome, with a well differentiated adenocarcinoma invading submucosal layers and some dysplastic glands. We believe that the adenocarcinoma represents a malignant transformation from solitary rectal ulcer syndrome, because similar to longstanding chronic idiopathic colitis, colorectal dysplasia and carcinoma may develop.

Growth patterns in various macroscopic types of noninvasive intramucosal colorectal carcinoma with special reference to apoptosis and cell proliferation

PURPOSE

Apoptotic cell death and cell proliferation play important roles in the histogenesis and development of colorectal carcinoma. The aim of this study was to examine the relationship between apoptosis and cell proliferation in various macroscopic types of intramucosal colorectal carcinoma in relation to the expression of p53 and bcl-2.

METHODS

One hundred forty cases with endoscopically or surgically resected intramucosal colorectal carcinoma were studied. There were 57 cases of polypoid-type carcinomas, 55 cases of superficial-type carcinomas, and 28 cases of granular-type, laterally spreading tumors. Polypoid-type carcinomas were pedunculated, subpedunculated, or sessile polyps. Superficial-type carcinomas were flat lesions with a smooth, even surface. Granular-type, laterally spreading tumors were superficially spreading lesions with aggregates of nodules and a granular surface. Apoptotic cells were identified by the in situ DNA nick end labeling method. Ki-67, p53, and bcl-2 expression were examined immunohistochemically.

RESULTS

The superficial-type carcinoma apoptotic index (30.9 percent) was significantly lower than that of polypoid-type carcinoma (54.4 percent) and granular-type, laterally spreading tumor (60.7 percent). The superficial-type carcinoma proliferative index (67.3 percent) was significantly higher than that of polypoid-type carcinoma (42.1 percent) and granular-type, laterally spreading tumor (28.6 percent). In superficial-type carcinomas the proliferative index in p53-positive carcinomas was significantly higher, and the apoptotic index was higher in carcinomas with a lower proliferative index. There was no significant difference in apoptotic index, proliferative index, or p53 protein overexpression between de novo carcinomas and those that had arisen in precursor adenomas.

CONCLUSIONS

The pattern of cell death and proliferation may vary with different macroscopic types of intramucosal colorectal carcinoma. Superficial-type colorectal carcinomas especially demonstrate diminished apoptosis and increased cell proliferation. This may be useful in understanding their biologic behavior.

MUC-1 expression as a predictor of the curative endoscopic treatment of submucosally invasive colorectal carcinoma

PURPOSE

This study was undertaken to clarify the clinical significance of MUC-1 expression in the endoscopic treatment of colorectal carcinoma with submucosal invasion.

METHODS

One hundred eighty-four colorectal carcinomas with submucosal invasion were examined. The depth of submucosal invasion was classified as scanty or massive. The histologic subclassification at the deepest invasive portion was defined as well-differentiated, moderately well-differentiated, moderately to poorly differentiated, poorly differentiated, or mucinous adenocarcinoma. MUC-1 expression was examined immunohistochemically at the deepest invasive portion. In addition, the Ki67 labeling index was also examined immunohistochemically.

RESULTS

Lymph node metastases were detected in 28 (15.2 percent) of 184 lesions. Lesions with both scanty submucosal invasion and well-differentiated or moderately well-differentiated adenocarcinomas had no lymph node metastases. MUC-1 expression was detected in 88 (47.8 percent) of 184 lesions and correlated significantly with the presence of lymph node metastases. The Ki67 labeling index also correlated significantly with lymph node metastases. Furthermore, lesions with both MUC-1-negative and low Ki67 labeling index showed no lymph node metastases, even in lesions with massive submucosal invasion. Multivariate analysis indicated that MUC-1 expression was one of the most important risk factors for lymph node metastases and histologic grade among the clinicopathologic factors usually examined.

CONCLUSION

MUC-1 expression is one of the accurate predictors of the presence of lymph node metastases among the clinicopathologic factors commonly used. Combined analysis of MUC-1 expression and Ki67 labeling index may be a useful indicator of lymph node metastases and may broaden the indications for the curative endoscopic treatment of carcinoma with massive submucosal invasion.

Invasion depth diagnosis of depressed type early colorectal cancers by combined use of videoendoscopy and chromoendoscopy

BACKGROUND

Depressed type early colorectal cancers are found less frequently than other polypoid cancers although they have a higher submucosal invasion rate. Recently videocolonoscopy and chromoendoscopy have become available and precise descriptions of these lesions are now routine. Because endoscopic mucosal resection is designated for intramucosal and focally extended submucosal (m-sm1) cancers, an evaluation of the characteristic findings indicating invasion depth with these modalities is important.

METHODS

Between January 1991 and March 1996, 64 depressed type early colorectal cancers were detected and treated. When a faint abnormality of the mucosa was suspected by routine videocolonoscopy, 0.1% of indigo carmine solution was sprayed on the mucosal surface (chromoendoscopy). Colonoscopic findings of m-sm1 cancers and moderately and massively extended submucosal (sm2-3) cancers were retrospectively reviewed and compared with confirmed histologic findings.

RESULTS

Characteristic colonoscopic findings needed for surgical operation were as follows: (1) expansion appearance, (2) deep depression surface, (3) irregular bottom of depression surface, and (4) folds converging toward the tumor. By using these findings, the invasion depth of depressed type early colorectal cancers could be correctly determined in 58 of 64 lesions (91%).

CONCLUSIONS

Characteristic colonoscopic findings obtained by a combination of videocolonoscopy and chromoendoscopy are useful for determination of the invasion depth of depressed type colorectal cancers, an essential factor in choosing a treatment modality.

Diagnostic findings in endoscopic screening of superficial colorectal neoplasia: results from a prospective study

BACKGROUND

A prospective study was carried out to clarify the efficacy of an endoscopic screening program for detecting superficial colorectal neoplasias by color changes such as faint redness or discoloration, which have been described as a key finding of these lesions in the literature.

METHODS

We enrolled 716 consecutive cases in this study, but more than half of them did not reveal any abnormalities colonoscopically.

RESULTS

Of the 716 cases, 48 (7%) were examined by magnifying colonoscopy with a dye spraying technique, following the detection of superficial color changes. Sixteen neoplastic lesions (in 16 cases) were detected among the 48 cases and the detection rate was calculated as 2.2% (16/716) in the total number of cases and 33% (16/48) in those showing color abnormalities. Histologically, all of the 16 were adenomas. These neoplastic lesions were most frequent (52%; 11/21) in those showing faint redness in an oval shape, whereas 14 (94%) of the 15 lesions were non-specific in those showing faint redness with unclear margin.

CONCLUSIONS

These results may confirm the diagnostic utility of color abnormality, particularly faint redness in an oval shape, for endoscopic screening of superficial colorectal neoplasias.

Somatically acquired genetic alterations in flat colorectal neoplasias

Somatically acquired mutations in several genes have been reported as playing an important role during colorectal tumorigenesis. Two alternative groups of carcinomas, termed LOH+ and RER+, have been defined on the basis of their genetic anomalies, a biallelic inactivation of the APC or the TGF-betaRII genes, occurring as an alternative, in LOH+ or RER+ tumors. It is a generally accepted hypothesis that most of colorectal cancers (CRC) develop from a pre-existing adenomatous polyp. Such benign lesions are usually exophytic polyps, a small proportion of adenomas having been described as flat lesions. The latter histological category has thus been proposed to bear specific genetic alterations. In order to examine this hypothesis, we have characterized a series of 44 flat colorectal neoplasias for their RER status and for somatic APC, KRAS and TGF-betaRII genes mutations. Flat colorectal neoplasias were found to be of the RER+ subtype in 22% of cases, all of them exhibiting a TGF-betaRII mutation. A mutation of the APC and KRAS genes has been found in 42% and 4% of tumors, respectively, none of these tumors being of the RER+ subtype. With the exception of a low KRAS mutation rate, flat adenomas appear to follow tumorigenesis pathways very similar to those identified in exophytic adenomas and carcinomas.

Desmoplastic response in biopsy specimens of early colorectal carcinoma is predictive of deep submucosal invasion

PURPOSE

The aim of this study was to evaluate the role of histopathology of biopsy specimens in predicting depth of infiltration in early colorectal carcinomas before treatment.

METHODS

Early colorectal carcinomas that had been resected surgically or endoscopically between 1984 and 1995 were analyzed. Histopathologic findings, including differentiation of adenocarcinoma and a desmoplastic response were investigated.

RESULTS

One hundred nine early colorectal carcinomas consisted of 73 lesions of carcinoma in situ, 13 submucosal carcinomas with minimum invasion, 8 lesions with moderate invasion, and 15 lesions with deep invasion. Of 73 carcinoma in situ lesions, 72 (approximately 99 percent) showed well-differentiated adenocarcinomas and no desmoplastic response. Twelve (92 percent) of 13 submucosal carcinomas with minimum invasion also revealed well-differentiated adenocarcinoma without a desmoplastic response. Sixty-three percent (5/8) of lesions with moderate invasion revealed well-differentiated adenocarcinoma. None of the lesions had a desmoplastic response. Among lesions with deep invasion, 73 percent (11/15) demonstrated moderately differentiated adenocarcinoma, and 11 lesions had a prominent desmoplastic response (73 percent; P < 0.01).

CONCLUSIONS

These results suggest that if histopathologic findings of biopsy specimens taken from them before treatment demonstrated adenocarcinoma associated with a desmoplastic response, the lesions had at least deep invasion carcinomas. These lesions should be resected surgically. Submucosal carcinomas with minimum invasion, which have no desmoplastic response, could be treated endoscopically.

High-resolution cross-sectional imaging of the gastrointestinal tract using optical coherence tomography: preliminary results

BACKGROUND

Optical coherence tomography (OCT) is a novel technique for noninvasive cross-sectional imaging with high spatial resolution (10 to 20 microm). OCT is similar to B-mode ultrasound except that it uses infrared light rather than ultrasound. We studied OCT imaging of the gastrointestinal (GI) tract in vitro to analyze the potential of this technique for endoscopic applications.

METHODS

Human gastrointestinal tissues harvested from surgical resection and autopsy specimens were used. Specimens were imaged within 5 hours of resection or snap frozen in liquid nitrogen. After imaging, OCT scan locations were carefully marked using dye microinjections, fixed, and prepared for routine histologic processing. OCT images were then compared and correlated with the histologic sections.

RESULTS

OCT images demonstrated clear delineation of the mucosa and submucosa in most specimens. Furthermore, microscopic structures such as crypts, blood vessels, or esophageal glands in the submucosa and lymphatic nodules were observed.

CONCLUSIONS

The resolution of OCT images of GI wall is sufficient to delineate the microscopic structure of the mucosa and submucosa. Potentially, OCT would allow in vivo imaging at endoscopy of the microstructure of the mucosa and submucosa. This would be particularly useful in the detection and staging of small lesions such as early stage cancers.

Early colorectal cancer: recognition, classification and treatment

BACKGROUND

With the introduction of colorectal cancer screening and improvements in endoscopic technology, the recognition and management of early colorectal cancer assumes increasing importance.

METHODS

A literature review was undertaken using Medline (National Library of Medicine, Washington DC, USA) searches of the headings early colonic, colorectal and rectal cancer, carcinoma and adenocarcinoma up to and including 1997. All relevant references were examined.

RESULTS AND CONCLUSION

The diagnosis, classification and treatment options are described. Accurate diagnosis, preoperative and histopathological staging is crucial in the management of early colorectal cancer.

Hereditary nonpolyposis colorectal cancer associated with duodenal carcinoma: a case report

Hereditary nonpolyposis colorectal cancer is an autosomal, dominantly inherited disease, characterized by an early age of onset, right colon predominance and an association with various extracolorectal malignancies. We present a case of a 47-year-old woman who met the clinical criteria for the diagnosis of hereditary nonpolyposis colorectal cancer from her past and family histories. She had undergone operations for uterine cancer (histology not confirmed) at age 35 and for advanced cancer of the ascending colon at age 45. Gastroendoscopy revealed a flat elevated lesion, 20 mm in size, with a protrusion (type IIa + Is) in the second portion of the duodenum in March 1996. Additionally, colonoscopy showed a flat elevated lesion, 30 mm in size, with an irregular and nodular surface (type IIa, laterally spreading tumor) in the descending colon. After the operation, the resected specimen of the duodenum histologically showed a well-differentiated adenocarcinoma associated with a tubulo-villous adenoma which had invaded the submucosal layer. The tumor of the colon was histologically confirmed to be a moderately-differentiated adenocarcinoma with submucosal invasion. A high frequency of replication error positivity (4/5 loci) was detected in both of the tumors. Reports of early cancer of the duodenum, associated with extracolorectal malignancies in hereditary nonpolyposis colorectal cancer, are very rare in the literature. Although it is difficult to determine which extracolorectal tumor sites should be taken into consideration by screening programs, we believe that careful observation by upper gastrointestinal endoscopy, which includes the duodenum, is necessary for patients with hereditary nonpolyposis colorectal cancer.

Differences in the diagnostic criteria used by Japanese and Western pathologists to diagnose colorectal carcinoma

BACKGROUND

In view of the many studies of early stage colorectal carcinoma from Japan, it is essential to know whether the criteria for the histologic diagnosis of colorectal carcinoma are similar in Japan and Western countries.

METHODS

Eight expert pathologists from Japan (4), North America (2), and Europe (2) individually reviewed microscope slides of 20 colorectal lesions from Japanese patients who had undergone endoscopic mucosal resection or surgery because early stage carcinoma and/or adenoma was suspected. The pathologists indicated the pathologic findings on which they based each diagnosis.

RESULTS

For 11 slides that showed adenoma according to the Western pathologists with low grade dysplasia according to at least half of them, the Japanese diagnosed definite carcinoma with or without adenoma in 4 cases and adenoma in 5, and in 2 cases they were equally divided between a diagnosis of adenoma and carcinoma. For five slides showing adenoma with high grade dysplasia according to the Western pathologists, the Japanese diagnosed definite carcinoma with adenoma in three cases and adenoma in one, and in one case they were equally divided between a diagnosis of adenoma and carcinoma. For one case in which the Western pathologists were equally divided between a diagnosis of carcinoma and adenoma with high grade dysplasia, all the Japanese pathologists diagnosed definite carcinoma with or without adenoma. Three slides showed definite carcinoma with or without adenoma, according to both the Western and the Japanese pathologists. The presence of invasion was the most important diagnostic criterion of colorectal carcinoma for the Western pathologists, whereas for the Japanese the nuclear features and glandular structures were more important.

CONCLUSIONS

In Japan, colorectal carcinoma is diagnosed on the basis of nuclear and structural criteria, even in cases considered by Western pathologists to be noninvasive lesions with low grade dysplasia. This diagnostic practice may contribute to the relatively high incidence of early stage colorectal carcinoma reported in Japan as compared with Western countries.

Application of magnifying chromoscopy for the assessment of severity in patients with mild to moderate ulcerative colitis

BACKGROUND

A magnifying colonoscope that enables high-power observation of the colorectal mucosa has been recently developed. The aim of this study was to investigate the value of the magnifying instrument in determining the severity of ulcerative colitis.

METHODS

Magnifying colonoscopy was performed in 41 patients with ulcerative colitis, and the findings in the rectum were graded according to network pattern and cryptal openings. These findings were correlated with endoscopic, clinical, and histologic severity of the disease.

RESULTS

Magnifying colonoscopy did not detect network pattern in 37% and cryptal opening in 24% of the subjects. The clinical, endoscopic, and histologic grades of activity were not different between groups divided by the presence or absence of each finding. However, when the two features were coupled, patients with visible network pattern and cryptal opening had a lower clinical activity index and lower grade of histologic inflammation than those in whom both findings could not be visualized.

CONCLUSIONS

Observation under magnifying colonoscopy can be another clue to determining the severity of disease in patients with ulcerative colitis.

Clinical investigation of colorectal cancer detected by follow-up colonoscopy after endoscopic polypectomy

PURPOSE

We analyzed the results of a long-term follow-up surveillance of patients with colorectal polyps after endoscopic polypectomy in terms of the cumulative incidence of subsequent colorectal cancer and the clinicopathologic characteristics of carcinomas detected by colonoscopy.

METHOD

The study cohort consisted of 6,715 patients who had received endoscopic resection of single or multiple colorectal polyps and then underwent periodic colonoscopy (or a combination of sigmoidoscopy and barium x-ray examination in some cases) during an average follow-up of six years (40,622 person-years in total).

RESULTS

During the follow-up, 31 cases of colorectal cancer containing 15 submucosal invasive carcinomas (T1,N0,M0) and 16 advanced carcinomas were detected. The cumulative incidence of colorectal cancer was analyzed for four subgroups of the 6,715 patients classified according to the diameter, grade of dysplasia, and histologic features of polyps. Furthermore, the depth of invasion, macroscopic configuration of submucosal invasive cancer, and site of colorectal cancer observed in the 31 cases were compared with those of a reference group of 1,497 patients with colorectal cancer treated at Takano Hospital during the same period. Submucosal invasive cancer was the most common type among the colorectal carcinomas detected during follow-up. In terms of macroscopic configuration of submucosal cancer, the superficial type was significantly more common than the protruded type. The superficial submucosal cancer showed a significantly longer interval to detection than the protruded submucosal cancer. By site of lesion, proximal colon cancer was significantly more common.

CONCLUSION

Follow-up colonoscopy appears to be useful in patients with larger polyps (>5 mm). Patients with severe dysplasia and those with malignant polyps should be followed-up carefully. Because submucosal cancer detected by follow-up examination after polypectomy showed higher rates of superficial-type cancer and proximal colon cancer, careful endoscopic examination of the entire colon is important.

Ki-ras point mutation in different types of colorectal carcinomas in early stages

PURPOSE

The aim of this study was to elucidate pathways of carcinogenesis in the colon and rectum by investigating Ki-ras point mutation in different types of colorectal carcinomas in the early stage.

METHODS

We analyzed rates of Ki-ras codon 12 mutations in 34 small, polypoid-type carcinomas (Tis or T1), 21 superficial-type carcinomas (Tis or T1), and 42 advanced carcinomas (T2, T3, and T4).

RESULTS

Frequency of Ki-ras mutations in superficial-type carcinomas was 14.3 percent (3/21), which was significantly lower than 50 percent (17/34) in small polypoid carcinomas and 40.5 percent (17/42) in advanced carcinomas. These data suggest that another pathway of colorectal carcinogenesis that does not involve Ki-ras point mutation might exist. Among the 17 small polypoid carcinomas with Ki-ras point mutation in which both adenomatous and carcinomatous tissue were examined, 12 showed a mutation of the same type in both carcinomatous and adenomatous tissues. In two cases, mutation was present only in carcinomatous tissue and not in adenomatous tissue; in the other three cases, Ki-ras point mutation was present only in adenomatous tissue but not in carcinomatous tissue.

CONCLUSIONS

These data suggest that carcinoma in a small polypoid lesion does not always develop from pre-existing adenoma with Ki-ras point mutation; in a small number of the polypoid-type early carcinomas, polyclonal composition concerning the Ki-ras gene may exist.

Asymptomatic colorectal cancer detected by screening

PURPOSE

Colorectal cancer screening has become prevalent. To discuss the efficacy of screening, we studied the characteristic of asymptomatic colorectal cancer detected by screening.

METHODS

This is a retrospective review of patients with colorectal cancer treated at our institution. During the past 20 years, 96 of 1,046 cases of colorectal cancer were asymptomatic and detected by screening. Sixty-one of these cases were detected in the recent five years. The initial screening procedures were fecal occult blood test in 51 cases, sigmoidoscopy or colonoscopy in 18, barium enema in 9, and other tests in 18.

RESULTS

Thirteen lesions (14 percent) were smaller than 1.0 cm and 32 (33 percent) were 1-2 cm in size. There were 34 Tis, 21 T1, and 8 T2 tumors. Of the 55 Tis or T1 lesions, 14 showed nonpolypoid growth (5 flat-elevated, 7 flat-elevated with depression, 1 flat, 1 depressed), and 12 of these were detected on endoscopy. Thirty-four cases were TNM Stage 0, 25 were Stage I, 16 were Stage II, 12 were Stage III, and 9 were Stage IV. Sixty-one percent of those detected by screening were in either Stage 0 or Stage I compared with 16 percent in the symptomatic group. Cumulative five-year disease-free survival rates were 100 percent for both Stage 0 and Stage I, 94 percent for Stage II, and 52 percent for Stage III. Overall cumulative five-year survival rate was 87 percent for those detected by screening, compared with 57 percent in symptomatic patients.

CONCLUSIONS

Asymptomatic cancers detected by screening were at a less advanced stage. In particular, many nonpolypoid early cancers were detected by endoscopic screening.

Nonpolypoid adenomas of the duodenum in patients with familial adenomatous polyposis (Gardner's syndrome)

BACKGROUND

Although duodenal adenomas are very common in familial adenomatous polyposis, we wished to emphasize our experience with finding nonpolypoid adenomas in the duodenum of patients with this disease.

METHODS

Duodenoscopy was performed in 23 patients with an established diagnosis of familial adenomatous polyposis or Gardner's syndrome.

RESULTS

Endoscopy revealed single or multiple nonpolypoid adenomas of the duodenum in 7 patients (30%). The lesions were smaller than 5 mm and were endoscopically recognized as flat or depressed reddish lesions; one lesion was completely flat and the remaining lesions were flat-topped elevations with a central depression. All of the lesions were histologically diagnosed as tubular adenoma with moderate epithelial atypia.

CONCLUSION

These findings suggest that duodenal nonpolypoid adenomas are common in familial adenomatous polyposis or Gardner's syndrome and that careful surveillance endoscopy seems necessary in patients with this disease.

Factors that influence bleeding in superficial-type colorectal tumors: study of endoscopic and histologic correlates

To clarify the mechanisms responsible for superficial-type colorectal tumor (STT) bleeding, 74 STTs were studied to determine whether their size, shape, surface area features, colorectal site, and level of invasion were correlated with bleeding. The bleeding rate, the proportion of specimens from patients with positive fecal occult blood test (FOBT) results relative to the total number of specimens in each morphological group and probability of an STT being an invasive submucosal carcinoma were positively correlated with tumor size, and bleeding was more common in submucosal than in intramucosal lesions. Logistic regression analysis indicated that the level of submucosal invasion had a significant influence on bleeding. It was also found that the length of erosion on the surface of STTs was significantly greater in bleeding tumors, and that the potential for invasion into the submucosa increased with the area of erosion.

Histologic classification of endoscopically removed flat colorectal polyps: a multicentric study

A total of 594 flat colorectal polyps, removed at endoscopy, were histologically classified into non-neoplastic (n = 49) and neoplastic (n = 545) polyps. Non-neoplastic polyps were subdivided into metaplastic (n = 45) and hyperplastic (n = 4), whereas neoplastic polyps were subdivided into adenomas (n = 481), intramucosal carcinomas (n = 28) and invasive adenocarcinomas (n = 36). Several adenoma phenotypes were discerned: tubular (n = 375), serrated (n = 59), villous (n = 39), mixed (n = 7) and fenestrated (n = 1). Intramucosal carcinomas were subdivided into tubular (n = 26) and serrated (n = 2), and invasive adenocarcinomas into tubular (n = 32), serrated (n = 3) and fenestrated (n = 1). The microscopic characteristics of each histologic phenotype described in this communication are defined and illustrated.

Small, flat colorectal neoplasias in long-standing ulcerative colitis detected by high-resolution electronic video endoscopy

BACKGROUND

High-resolution video endoscopy complemented with chromoscopy allows for more detailed visualization of the colonic mucosal surface.

METHODS

Using high-resolution video endoscopy and chromoscopy, we investigated 85 patients with extensive ulcerative colitis with a disease duration of at least 10 years who were taking part in a cancer surveillance program.

RESULTS

In 38 of the 85 patients, 104 polyps were detected at endoscopy. Seventy-seven (74%) of the 104 polyps were endoscopically flat, 21 (20%) were sessile, 3 (3%) were pedunculated, and 3 (3%) had no recorded morphology. Twenty-three (22%) polyps were neoplastic (15 flat, 5 sessile, 2 pedunculated, 1 not recorded). Low-grade dysplasia was found in 21 of the 23 neoplastic polyps and high-grade dysplasia in the remaining 2 (1 flat tubular adenoma and 1 sessile villous adenoma with invasive growth). Flat polyps were small, with a diameter of 5 mm or less in 73% (n = 56) of cases. At histology flat polyps revealed either flat adenomas (n = 11; 14.3%), tubular or villous structures with dysplastic cells at the lower part of the crypts (n = 4; 5.2%), flat hyperplastic polyps (n = 26; 34%), inflammatory mucosa (n = 5; 6.5%), or mucosa in remission (n = 31; 40%).

CONCLUSION

The use of high-resolution video endoscopy complemented with chromoscopy in ulcerative colitis enables the detection of flat neoplastic polyps. The existence of those hitherto undetected neoplasms in ulcerative colitis and their possible role in the histogenesis of colorectal cancer in ulcerative colitis deserve further investigation.

Efficacy of high-frequency ultrasound probes for the preoperative staging of invasion depth in flat and depressed colorectal tumors

BACKGROUND

Flat and depressed nonpolypoid types of colorectal tumors have drawn much attention. Since endoscopic mucosal resection technique is available, it is of great importance to distinguish intramucosal carcinoma from invasive carcinoma because determination of the invasion depth is essential for choosing this therapy. The usefulness of high-frequency (20 MHz) ultrasound probes for preoperative staging of invasion depth in this type of colorectal tumor was evaluated.

METHODS

Forty-nine cases of flat and depressed tumors were examined with the ultrasound probe and diagnostic accuracy was confirmed by comparing ultrasonic images with the pathologic findings of the specimens resected either by endoscopic mucosal resection or surgical operation.

RESULTS

The normal colonic wall was visualized as a nine-layered structure and the muscularis mucosae was depicted in 37 (76%) of 49 cases. Flat and depressed tumors were visualized as hypoechoic lesions and the invasion depth was accurately diagnosed in 43 (88%) of 49 lesions.

CONCLUSIONS

High-frequency ultrasound probes proved to be useful in determining the invasion depth and therapeutic strategy in flat and depressed colorectal tumors.

Diagnosis of colorectal tumorous lesions by magnifying endoscopy

BACKGROUND

The magnifying colonoscope allows 100-fold magnified viewing of the colonic surface.

METHODS

We examined 2050 colorectal tumorous lesions by magnifying endoscopy, stereomicroscopy, and histopathology and classified these lesions according to pit pattern. Based on stereomicroscopy, lesions with a type 1 or 2 pit pattern were nontumors, whereas lesions with types 3s, 3L, 4, and/or 5 pit patterns were neoplastic tumors.

RESULTS

The pit patterns observed by magnifying endoscopy were fundamentally similar to those demonstrated in stereomicroscopic images. When the diagnosis by magnifying endoscopy was compared with the stereomicroscopic diagnosis, there was agreement in 1130 of 1387 lesions (81.5%). True neoplasms could be differentiated from non-neoplastic lesions. Of lesions with a type 5 pit pattern with a bounded surface, 11 of 22 (50%) were found to be invasive cancers with involvement of the submucosal layer. If this pit pattern is found to involve a relatively broad area of the mucosal surface, extensive malignant invasion (sm-massive) should be strongly suspected.

CONCLUSIONS

The magnifying colonoscope provides an accurate instantaneous assessment of the histology of colorectal tumorous lesions. This may help in decision making during colonoscopy.

Flat serrated adenomas of the colorectal mucosa

A total of 47 flat serrated neoplasias of the colorectal mucosa are presented: 44 were flat serrated adenomas and the remaining 3 flat serrated adenocarcinomas arising in flat serrated adenomas. These lesions were found among 600 flat mucosal lesions removed at colonoscopy during a 3-year period (1992 and 1994) at the Karolinska Hospital. Thirty-five of the 47 patients (74%) were males and the remaining 12 (26%), females. Depending upon the degree of cellular dysplasia within the epithelium, serrated adenomas were divided into those with low-grade dysplasia (LGD), when the dysplastic nuclei were present in the deeper half of the epithelium, and those with high-grade dysplasia (HGD), when the dysplastic nuclei were found even in the upper half of the epithelium. LGD was present in 37 (84.1%) of the 44 serrated adenomas and HGD in the remaining 7 (15.9%). Depending upon the topographic distribution of the dysplastic epithelium within the crypts, flat serrated adenomas were divided into type I, when the dysplastic epithelium was limited to the lower half of the serrated crypts, and type II, when the dysplastic epithelium was even present in the superficial half of the serrated crypts. Of the 44 serrated adenomas, 38 (86.1%) were type I and the remaining 6 (13.9%) type II. The dysplastic epithelium seemed to originate at the base of the crypts and to progress upwards, replacing the scalloped, serrated epithelium of the sides of the crypts. Invasive adenocarcinomas (i.e., with submucosal extension) were seen to arise from flat serrated adenomas with LGD type I (n = 2) or with HGD type II (n = 1). This preliminary survey suggests that flat serrated adenomas of the colorectal mucosa may be lesions with a propensity to evolve into invasive adenocarcinoma, irrespective of the degree of the epithelial dysplasia or of their extension along the crypts.

Nonpolypoid adenomas and adenocarcinomas found in background mucosa of surgically resected colons

BACKGROUND

Nonpolypoid (depressed or flat) neoplasias are rarely seen in the colon and rectum. We previously reported their histogenesis and characteristics in patients with familial adenomatous polyposis (FAP), but their development in patients without FAP has not been studied systematically.

METHODS

Three hundred specimens of large intestinal mucosa surgically resected from patients with cancers or other diseases, excluding FAP, were examined with a dissecting microscope. The morphologic types, sizes, locations, and frequencies of detectable colorectal neoplasias, and their histologic features, were analyzed.

RESULTS

A total of 297 adenomas (240 polypoid, 32 flat, and 25 depressed type) were obtained. Nonpolypoid adenomas were most frequently found in the transverse and descending colon. Almost all depressed adenomas (24 of 25; 96%) were less than 3 mm in greatest dimension and almost all flat adenomas (31 of 32; 96.9%) were less than 3.5 mm in greatest dimension. Three minute, nonpolypoid adenocarcinomas (mean size, 2.6 mm; range, 2.4-2.9 mm) were also detected, two of them already invaded the submucosal layer.

CONCLUSIONS

Minute nonpolypoid type adenomas may be present in the background mucosa of patients without FAP. This study suggests that even minute nonpolypoid adenocarcinomas have an increased potential for endophytic growth.

Mutation of p53 tumor suppressor gene in flat neoplastic lesions of the colorectal mucosa

PURPOSE

In a recent comparative histologic survey of flat colorectal neoplasias, we found more lesions with high-grade dysplasia (HGD) and carcinoma in Japanese than in Swedish patients. The purpose of this work was to assess the p53 protein overexpression in flat colorectal neoplasias in Swedish patients and to compare results with those reported in Japan.

METHOD

A total of 57 neoplastic lesions of the colorectal mucosa were investigated: 29 had been regarded both at endoscopy and at histology as flat and the remaining 28 as exophytic. Deparaffinized, rehydrated sections were treated immunohistochemically to detect the p53 protein. Lesions having a moderate (++) or high ( ) staining were considered as overexpressing the p53 protein.

RESULTS

Results indicated that 16.7 percent (1/6) of the exophytic adenomas with low-grade dysplasia (LGD) had distinct p53 overexpression as well as 57.1 percent (8/14) of those with HGD and 87.5 percent (7/8) with invasive growth. In flat neoplastic lesions, 7.7 percent (1/13) of the tubular adenomas with LGD, 25 percent (3/12) of tubular adenomas with HGD, and 75 percent (3/4) of adenocarcinomas arising in flat adenomas had p53 overexpression.

CONCLUSIONS

In Swedish patients, the proportion of flat and exophytic colorectal neoplasias showing p53 immunoreactivity increased with increasing degree of dysplasia, the highest percent being recorded in lesions with invasive growth. Because a similar stepwise increase was reported for exophytic and flat colorectal neoplasias in Japan, it seems that the comparison of results in both countries is justifiable. One possible conclusion from this comparison is that the higher proportion of flat neoplastic colorectal lesions with HGD and carcinoma in the Japanese (compared with the Swedish) takes place for reasons extraneous to the overexpression of the p53 protein.

Management of early invasive colorectal cancer. Risk of recurrence and clinical guidelines

PURPOSE

The purpose of this study was the evaluation of various factors in the formulation of guidelines for treatment of early invasive colorectal cancer, in which malignant cells extend through the muscularis mucosa into the submucosa but do not deeply invade the muscularis propria.

METHOD

A total of 182 patients were followed for at least five years or until death, with early invasive cancer diagnosed between 1982 and 1989. Patients were grouped according to the level of invasion, as follows: 64 patients with slight carcinoma invasion of the muscularis mucosa (200-300 microns; sm1), 82 with intermediate invasion (sm2), and 36 with carcinoma invasion extending to the inner surface of the muscularis propria (sm3).

RESULT

The configuration, diameter, and histologic grade of adenocarcinoma and lymphovascular invasion were correlated with level of invasion. After endoscopic polypectomy or local resection, 4 patients showed local recurrence and 13 patients showed lymph node metastasis. None of these 17 patients had sm1 disease. The level of invasion, configuration, and location were significant risk factors for development of lymph node metastasis or local recurrence (P < 0.05), but lymphovascular invasion, histologic grade, and diameter were not risk factors.

CONCLUSIONS

Preoperative assessment of the level of invasion using this classification, in which the submucosa is divided into three depths, may decrease the incidence of unnecessary surgery for sessile polyps. Assessment according to the level of invasion is useful in the formulation of appropriate guidelines for the treatment of early invasive cancer.

Endoscopic treatment of submucosal invasive colorectal carcinoma with special reference to risk factors for lymph node metastasis

A clinicopathological analysis of the risk factors for lymph node metastasis was performed in 177 patients with submucosal invasive colorectal carcinoma (CRC). The submucosal deepest invasive portion was histologically subclassified as well (W), moderately (M), or poorly (Por) differentiated. M type was further subdivided into moderately-well (Mw) and moderately-poorly (Mp) differentiated. The pattern of tumor growth was classified as polypoid growth (PG) and non-polypoid growth (NPG). Lymph node metastasis was detected in 21 (12%) of the 177 patients. Macroscopically, type IIc and IIa + IIc lesions showed a significantly higher incidence of lymph node metastasis (44% and 30%) than type IIa and I (4% and 8%). Regarding the histologic subclassification, Por and Mp lesions showed a significantly higher incidence of lymph node metastasis (67% and 37%) than W and Mw lesions (4% and 14%). NPG tumors showed a significantly higher incidence of lymph node metastasis (29%) than PG tumors (7%). The depth of submucosal invasion and lymphatic invasion (ly) were also significantly correlated with the incidence of lymph node metastasis (submucosal scanty (sm-s) invasion 4%, massive invasion 20%; ly(+) 23%, ly(-) 5%). None of the lesions with both sm-s invasion and of W or Mw type showed lymph node metastasis. These results indicate that submucosal invasive CRC with both sm-s invasion and of W or Mw type, which shows no ly, is the appropriate indication for endoscopic curative treatment.

Flat adenomas and flat adenocarcinomas of the colorectal mucosa in Japanese and Swedish patients. Comparative histologic study

PURPOSE

In recent years, flat adenomas of the colorectal mucosa have been intensively investigated by Japanese pathologists. Results of that work indicate that flat adenomas may antedate the development of colorectal carcinomas. Because of differences in the histologic definition of flat adenomas with severe dysplasia and with intramucosal carcinoma within the group, one single observer having both Western and Asian training in pathology reviewed the material.

METHODS

A total of 287 flat colorectal lesions were reviewed: 109 from the Karolinska Hospital, Stockholm, 137 from the Tokyo Medical and Dental University (TMDU) (which included 5 cases from the Nagoya City University), and 41 from the Cancer Institute (CI), Tokyo. Lesions were histologically classified following strict histologic criteria. Thus, flat adenomas were divided into those having low-grade dysplasia (LGD; having dysplastic cells in the deeper half of the epithelium), high-grade dysplasia (HGD; dysplastic cells were found even in the superficial half of the epithelium), intramucosal carcinoma (dysplastic glands displayed molding with buddings and often a cribriform pattern), and adenocarcinoma (braking through the muscularis mucosa, with neoplastic cells in the submucosal layer or deeper).

RESULTS

Whereas in Stockholm only 14.7 percent of lesions had HGD, as much as 56.9 percent and 56.1 percent, respectively, had HGD at the two Tokyo Hospitals. Intramucosal carcinomas were not found in the Stockholm material but occurred in 2.2 percent of lesions seen at TMDU and in 4.9 percent of those seen at the CI. Notably, only 2.7 percent of the specimens at Karolinska Hospital had invasive adenocarcinoma, but it was seen in as many as 4.4 percent at TMDU and 21.9 percent at the CI.

CONCLUSIONS

This study indicates that there were histologic differences between flat neoplasias of the colorectal mucosa harvested in Stockholm and Tokyo. In Japan lesions were obviously more advanced (in terms of HGD) and more aggressive (in terms of intramucosal and submucosal invasion). The cause for the differences found in those two disparate geographic regions remains poorly understood. The results, however, may help us understand some of the unclear points and discussions appearing in the literature on this subject.

p53 overexpression in flat serrated adenomas and flat tubular adenomas of the colorectal mucosa

The expression of the p53 protein was investigated in flat serrated neoplasias as well as in other histological phenotypes of flat or exophytic hyperplasias or neoplasias of the colorectal mucosa. A total of 104 such lesions were analyzed: 24 were flat serrated neoplasias (22 flat serrated adenomas and 2 flat serrated adenocarcinomas), 26 flat tubular adenomas, 17 flat hyperplastic polyps, 29 exophytic tubular and/or villous neoplasias (23 adenomas and 6 exophytic adenocarcinomas) and the remaining 8, exophytic hyperplastic polyps. Deparaffinized, rehydrated sections were treated immunohistochemically to detect those overexpressing the p53 protein. Lesions having slight (+), moderate (++) or intense ( ) staining were considered immunoreactive. The results showed that 50% of the flat serrated adenomas with low-grade dysplasia (LGD) and 66.7% of those with high-grade dysplasia (HGD) had p53 immunoreactivity. None of the flat tubular or of the exophytic adenomas with LGD expressed p53, but immunoreactivity was present in 61.5% of the flat tubular adenomas with HGD and in 52.3% of the exophytic adenomas with HGD. All adenocarcinomas had an intense p53 reaction. Weak p53 expression was demonstrated by 11.7% of the flat hyperplastic polyps but none of the exophytic polyps reacted. The occurrence of p53 expression in flat serrated adenomas with LGD suggested that, despite its low histological profile, one-half of those lesions could be biologically already committed to independent growth. The occurrence of p53 expression in nearly 12% of the flat hyperplastic polyps was totally unexpected and deserves further investigation. Flat serrated adenoma emerges as a novel, independent histological entity among the various phenotypes of flat neoplasias of the colorectal mucosa.

Clinicopathologic features of early rectal carcinoma and indications for endoscopic treatment

PURPOSE

This study was undertaken to clarify the indications for endoscopic treatment.

METHODS

Clinical and pathologic features of 191 lesions in 180 patients with early rectal carcinoma were examined, including 110 intramucosal carcinomas and 81 carcinomas with submucosal invasion (submucosal carcinomas). All lesions had been endoscopically or surgically resected at the National Cancer Center Hospital between 1976 and 1990.

RESULTS

Metastasis to regional lymph nodes (LN metastasis) was seen in 0 percent (0/39) of intramucosal carcinomas and 9.2 percent (6/65) of submucosal carcinomas in the surgically treated patients. The incidence of LN metastasis was higher for lesions larger than 10 mm in diameter, for those showing massive submucosal invasion, and for moderately differentiated adenocarcinomas. LN metastases were associated significantly with lymphatic invasion.

CONCLUSIONS

These results suggest that early rectal carcinomas should be resected surgically if they 1) show massive submucosal invasion, 2) are classified as moderately differentiated adenocarcinomas, and 3) are larger than 10 mm in diameter. In patients with both scanty submucosal invasion and features of well-differentiated adenocarcinoma or intramucosal carcinoma and if no other risk factors for LN metastasis are present, such as lymphatic invasion by the primary lesion, surveillance may suffice after endoscopic resection.

Small flat cancer of the rectum: clinicopathologic and endoscopic features

The clinicopathologic and endoscopic features of 15 patients with small flat cancer of the rectum were investigated. Whereas 4 patients had hematochezia, the remaining 11 patients were asymptomatic, and stool positive for occult blood was the only remarkable clinical feature in 8 of them. Endoscopic features were slight elevation with central depression in 8 lesions, flat-topped elevation in 4, and shallow depression with irregular margin in 3. The surface of the tumor was often faint red in color and frequently characterized by mucosal friability. Five flat rectal cancers were missed during initial endoscopy, and they were found by repeated endoscopic examination. Three flat cancers were not identified in the distal rectum until retroflexed colonoscopic observation was performed. Although all tumors were smaller than 2 cm in diameter and 6 of them were under 1 cm, 9 lesions had deeply invaded the submucosal layer and 7 tumors showed lymphovascular permeation. Two lesions of 1 cm or greater had metastasized to perirectal lymph nodes. These results suggest that careful observation during endoscopy is necessary to detect flat rectal cancers, and a U-turn to examine the anorectal junction should be routinely done in the appropriate age group.

Flat serrated adenomas and flat tubular adenomas of the colorectal mucosa: differences in the pattern of cell proliferation

In the present work we have investigated the cell proliferation pattern of flat serrated adenomas and flat tubular adenomas. For this purpose tissue sections from 23 consecutive flat serrated adenomas and 22 consecutive flat tubular adenomas of the colorectal mucosa were challenged with MIB1, a monoclonal antibody directed against a proliferation-related antigen. The results (including semi-quantitative studies) demonstrated that, whereas flat serrated adenomas had a high cell proliferation at the lower part of the crypts, flat tubular adenomas had a high cell proliferation in the upper part of the crypts. In serrated adenomas with invasive adenocarcinoma, high cell proliferation was demonstrated both at the lower portion of the crypts and in the subjacent submucosa. This suggests that the cells of the lower portion of the crypts in serrated adenomas are truly neoplastic, with the capacity to evolve into invasive growth. The difference in cell proliferation between the two types of flat lesions reported here is a new argument in favor of the classification of flat serrated adenomas as a novel and independent type of neoplastic change of the colorectal mucosa.

Flat neoplastic lesions of the colon and rectum detected by high-resolution video endoscopy and chromoscopy

Because small flat colorectal neoplastic lesions (i.e., flat adenomas and flat adenocarcinomas) may be as translucent as the surrounding mucosa, they can remain undetected at conventional endoscopy. By combining high-resolution video endoscopy and chromoscopy, we detected 109 colorectal flat neoplastic lesions in 55 of 232 patients studied. Forty-three (78%) of the 55 patients with flat neoplastic lesions were over 60 years of age. No flat neoplastic lesions were seen in patients under 40 years of age. Flat neoplastic lesions were more frequent in men (35%) than in women (15%). Seventy-seven (71%) of the 109 flat neoplastic lesions measured 0.5 cm or less, 23 (21%) between 0.6 and 1.0 cm, and 9 (8%) more than 1.0 cm. Low-grade dysplasia and high-grade dysplasia were found in 94 (86%) and 13 (12%) of the flat neoplastic lesions, respectively. Adenocarcinoma was diagnosed in 3 (3%) flat lesions: 1 (1%) carcinoma originating in a flat adenoma and 2 (2%) adenocarcinomas without recognizable adenomatous elements. No adenocarcinomas were seen in lesions measuring 1.0 cm or less. Fourteen flat neoplastic lesions had a central depression at endoscopy. Flat neoplastic lesions with central depression more frequently showed high-grade dysplasia (43%) than did flat neoplastic lesions without central depression (7%). Central depression in flat neoplastic lesions should be considered a possible endoscopic marker for severe dysplasia. Our results suggest that flat neoplastic lesions occur more frequently than previously reported in Scandinavia. Flat adenomas may play an important role in the histogenesis of colorectal cancer.