Significance of histologic criteria for the management of patients with malignant colorectal polyps and polypectomy

Pathological features associated with metastasis in patients with early invasive (pT1) colorectal carcinoma in colorectal polyps

AIMS

Colorectal carcinoma (CRC) arising in a colorectal polyp with invasion limited to the submucosa is sufficiently treated by complete endoscopic resection alone in many cases. Histological features of the carcinoma including tumour size, vascular invasion and poor tumour differentiation or evidence of de-differentiation, such as tumour budding, are associated with a higher risk for metastasis such that oncological resection is recommended. However, most malignant polyps with these features do not have lymph node metastases at the time of resection, so there is a need for better refinement of the histological risk features.

METHODS AND RESULTS

A total of 437 consecutive colorectal polyps with submucosal invasive carcinoma from a single centre, 57 of which had metastatic disease, were supplemented by 30 cases with known metastatic disease from two additional centres. Clinical and histological features of the polyp cancers were reviewed looking for differences between the 87 cancers with metastatic disease and the remaining cases without metastasis. A subgroup of 204 polyps removed intact was also analysed to ensure maximum histological accuracy.

CONCLUSIONS

This study confirmed larger invasive tumour size, vascular invasion and poor tumour differentiation as adverse predictive features. Prominent peritumoral desmoplasia and high cytological grade were additional adverse features. A predictive logistic regression model comprised of (i) presence of any form of vascular invasion; (ii) presence of high tumour budding (BD3); (iii) width of invasive tumour component > 8 mm; (iv) depth of invasive tumour > 1.5 mm; and (v) the finding of prominent expansile desmoplasia located within and beyond the deep invasive edge of the carcinoma, showed excellent performance in predicting metastatic disease.

Patient and pathological predictors of management strategy for malignant polyps following polypectomy: a systematic review and meta-analysis

PURPOSE

Malignant polyps present a treatment dilemma for clinicians and patients. This meta-analysis sought to identify the factors that predicted the management strategy for patients diagnosed with a malignant polyp.

METHODS

A literature search was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Cochrane Collaboration prognostic studies guidelines. Reports from 1985 onwards were included, data on patient and pathological factors were extracted and random effects meta-analysis models were used.

RESULTS

Fifteen studies were included. Seven studies evaluated lymphovascular invasion (LVI). The odds of surgery were significantly higher in malignant polyps with LVI (OR 2.20, 95% CI 1.36-3.55). Ten studies revealed the odds of surgery were significantly higher with positive polypectomy margins (OR 8.09, 95% CI 4.88-13.40). Tumour differentiation was compared in eight studies. There were significantly lower odds of surgery in malignant polyps with well/moderate differentiation compared with poor differentiation (OR 0.31, 95% CI 0.21-0.46). There were non-significant trends favouring surgical resection in younger patients, males and Haggitt 4/Kikuchi Sm3 lesions. There was considerable heterogeneity in the meta-analyses for the variables age, gender, polyp morphology and Haggitt/Kikuchi level (I² > 75%).

CONCLUSION

This meta-analysis has demonstrated that LVI, positive polypectomy resection margins, and poor tumour differentiation significantly predict malignant polypectomy patients who underwent subsequent surgery. Age and gender were important factors predicting management, but not consistently across studies, whilst polyp morphology and Haggitt/Kikuchi levels did not significantly predict the management strategy. Further research may assist in understanding the management preferences.

Pathological assessment of endoscopic resections of the gastrointestinal tract: a comprehensive clinicopathologic review

Endoscopic resection (ER) allows optimal staging with potential cure of early-stage luminal malignancies while maintaining organ preservation. ER and surgery are non-competing but complementary therapeutic options. In addition, histological examination of ER specimens can either confirm or refine the pre-procedure diagnosis. ER is used for the treatment of Barrett's related early carcinomas and dysplasias, early-esophageal squamous cell carcinomas and dysplasias, early gastric carcinomas and dysplasia, as well as low-risk submucosal invasive carcinomas (LR-SMIC) and, large laterally spreading adenomas of the colon. For invasive lesions, histological risk factors predict risk of lymph node metastasis and residual disease at the ER site. Important pathological risk factors predictive of lymph node metastasis are depth of tumor invasion, poor differentiation, and lymphovascular invasion. Complete resection with negative margins is critical to avoid local recurrences. For non-invasive lesions, complete resection is curative. Therefore, a systematic approach for handling and assessing ER specimens is recommended to evaluate all above key prognostic features appropriately. Correct handling starts with pinning the specimen before fixation, meticulous macroscopic assessment with orientation of appropriate margins, systematic sectioning, and microscopic assessment of the entire specimen. Microscopic examination should be thorough for accurate assessment of all pathological risk factors and margin assessment. Site-specific issues such as duplication of muscularis mucosa of the esophagus, challenges of assessing ampullectomy specimens and site-specific differences of staging of early carcinomas throughout the gastrointestinal tract (GI) tract should be given special consideration. Finally, a standard, comprehensive pathology report that allows optimal staging with potential cure of early-stage malignancies or better stratification and guidance for additional treatment should be provided.

Optimal Management of Malignant Polyps, From Endoscopic Assessment and Resection to Decisions About Surgery

Colorectal cancer is defined clinically as invasion of dysplastic cells into the submucosa. Lesions with submucosal invasion but without invasion into the muscularis propria are generally called malignant polyps. A stepwise approach produces optimal management of malignant polyps (including polypoid and flat/depressed lesions). The first step is to avoid endoscopic resection of non-pedunculated lesions with endoscopic features that predict deep submucosal invasion. Lesions without such features are candidates for endoscopic resection. The second step is to assess candidates for endoscopic resection for features that predict an increased risk of superficial submucosal invasion. Such lesions should be considered for en bloc endoscopic excision if feasible. The third step is giving patients with endoscopically resected malignant polyps good advice regarding whether to undergo adjuvant therapy, usually surgery. We review the endoscopic and histologic criteria that guide clinicians through these steps.

Ablative therapies for colorectal polyps and malignancy

Endoscopic techniques are gaining popularity in the management of colorectal polyps and occasionally superficial cancers. While their use is in many times palliative, they have proven to be curative in carefully selected patients with polyps or malignancies, with less morbidity than radical resection. However, one should note that data supporting local and ablative therapies for colorectal cancer is scarce and may be subject to publication bias. Therefore, for curative intent, these techniques should only be considered in highly select cases as higher rates of local recurrences have also been reported. The aim of this review is to explain the different modalities of local and ablative therapies specific to colorectal neoplasia and explain the indications and circumstances where they have been most successful.

Lymphatic invasion identified with D2-40 immunostaining as a risk factor of nodal metastasis in T1 colorectal cancer

BACKGROUND

The management of T1 colorectal cancer after local resection is controversial. Regional lymph node metastasis often occurs, requiring subsequent colonic resection. The aim of this study was to reevaluate the risk factors of nodal metastasis of T1 colorectal cancer, especially to examine lymphatic vessel invasion in serially prepared hematoxylin and eosin sections and D2-40 immunostained sections to determine which is a better indicator of lymph node metastasis of T1 colorectal cancer.

METHODS

The study investigated 120 patients who underwent bowel resection and were histologically diagnosed to have T1 colorectal cancer in Kanagawa Cancer Center Hospital from 1995 to 2005. Serially prepared paraffin sections were stained with hematoxylin and eosin, or immunostained with D2-40 antibody or von Willebrand factor, and reevaluated for lymphatic vessel invasion and other risk factors, including venous invasion, histological grade, depth of submucosal invasion, and budding.

RESULTS

Lymphatic invasion diagnosed with either hematoxylin and eosin staining (p = 0.022), or D2-40 immunostaining (p = 0.001), and budding (p = 0.013) were significant risk factors for lymph node metastasis in the univariate analysis. Venous involvement, histological grade, or depth of submucosal invasion was not significant. The multivariate logistic regression analysis for the three risk factors found lymphatic invasion diagnosed with D2-40 as an independent risk factor (odds ratio 6.048, p = 0.018, CI 1.360-26.89). The sensitivity, specificity, positive predictive value, and negative predictive value were 58 %, 88 %, 35 %, and 95 %, respectively.

CONCLUSIONS

Lymphatic vessel invasion diagnosed with D2-40 was a better indicator to evaluate the risk for lymph node metastasis by T1 colorectal cancer.

Prospective comparison of contrast enhanced CT colonography and conventional colonoscopy for detection of colorectal neoplasms in a single institutional study using second-look colonoscopy with discrepant results

BACKGROUND

Colorectal cancer is the second leading cause of death from cancer in Western countries. Early detection by colorectal cancer screening can effectively cut its mortality rate. CT colonography represents a promising, minimally invasive alternative to conventional methods of colorectal carcinoma screening.

AIMS

The purpose of this prospective single institutional study was to compare the abilities of routine clinical CT colonography and conventional colonoscopy to detect colorectal neoplasms using second-look colonoscopy to clarify discrepant results.

PATIENTS AND METHODS

CT colonography was performed in 100 symptomatic patients using contrast enhanced multidetector CT followed by conventional colonoscopy on the same day. If results were discrepant, a second-look colonoscopy was performed after unblinding. CT colonographic findings were compared with those of conventional colonoscopy.

RESULTS

Conventional colonoscopy found 122 colorectal neoplasms in 49 patients. The overall sensitivity of CT colonography at detecting patients with at least one polyp 6 mm or larger was 76% and its specificity was 88%. Its by-patient sensitivity for polyps 10 mm or larger was 95% and its specificity was 98%. By-polyp sensitivities were 71% for polyps 10 mm or larger, and 61% for polyps 6 mm or larger. A second-look colonoscopy was performed in 19 patients and two initial false-positive findings of CT colonography were reclassified as true-positive. For conventional colonoscopy, this produced a by-polyp sensitivity of 94% for detection of lesions 6 mm and larger.

CONCLUSIONS

CT colonography had both a high by-patient sensitivity and specificity for detection of clinically important colorectal neoplasms 10 mm or larger. This suggests that CT colonography has the potential to become a valuable clinical screening method for colorectal neoplasms.

Risk factors for an adverse outcome in early invasive colorectal carcinoma

BACKGROUND & AIMS

Various histologic findings exist for managing patients with malignant polyps. Our goal was to determine the criteria for a conservative approach to patients with locally excised early invasive carcinoma.

METHODS

In 292 early invasive tumors (local resection followed by laparotomy [80 tumors, group A], local resection only [41 tumors, group B], and primarily laparotomy [171 tumors, group C], potential parameters for nodal involvement were analyzed. The status of the endoscopic resection margin also was examined for the risk for intramural residual tumor.

RESULTS

Unfavorable tumor grade, definite vascular invasion, and tumor budding were the combination of qualitative factors that most effectively discriminated the risk for nodal involvement in patients in groups A-C. The nodal involvement rate was 0.7%, 20.7%, and 36.4% in the no-risk, single-risk, and multiple-risks group, respectively. Thirty-two and 9 patients from group B were assigned to the no-risk and one-risk group, respectively; extramural recurrence occurred in 2 patients with risk factors. Considering quantitative risk parameters for submucosal invasion (i.e., width > or =4000 microm or depth > or =2000 microm), nodal involvement (including micrometastases) was not observed in the redefined no-risk group that accounted for about 25% of the patients from groups A and C. An insufficiency of endoscopic resection could be evaluated most precisely based on the coagulation-involving tumor, rather than the 1-mm rule for the resection margin.

CONCLUSIONS

Provided that the criterion of sufficient excision is satisfied, the absence of an unfavorable tumor grade, vascular invasion, tumor budding, and extensive submucosal invasion would be the strict criteria for a wait-and-see policy.

Inhibition of human colon cancer cell growth by antisense oligodeoxynucleotides targeted at basic fibroblast growth factor

BACKGROUND

Basic fibroblast growth factor has been shown to be mitogenic in colon cancer cell lines. In human malignant melanoma cells, antisense oligodeoxynucleotides targeted against basic fibroblast growth factor messenger RNA significantly inhibit cell growth. However, the efficacy of such an antisense oligodeoxynucleotide strategy has not been evaluated for colon cancer cells.

AIM

To investigate whether basic fibroblast growth factor can stimulate the growth of HT-29 human colon cancer cells and whether antisense oligodeoxynucleotides can inhibit growth of these cells at baseline.

METHODS

Western blotting analyses were used to confirm the presence of basic fibroblast growth factor protein in this cell line. Cell growth was assessed after 2, 4 and 6 days of treatment by cell counting using the trypan blue exclusion method. Phosphorothioate-modified oligodeoxynucleotides (10 microM) were used, complementary to codon 60 of the basic fibroblast growth factor messenger RNA. Cationic liposomes (DOTAP) were used to enhance the cellular uptake of the oligodeoxynucleotides.

RESULTS

Western blotting demonstrated the presence of basic fibroblast growth factor protein in this cell line. Basic fibroblast growth factor (1-40 ng/mL) dose-dependently stimulated cell growth and peak values were obtained at a dose of 20 ng/mL. By contrast, antisense oligodeoxynucleotide treatment significantly inhibited cell growth compared with the sense oligodeoxynucleotide-treated cells (P=0.007). This inhibition was reversed by the addition of basic fibroblast growth factor, 20 ng/mL.

CONCLUSION

Treatment targeted against basic fibroblast growth factor messenger RNA inhibits growth of HT-29 human colon cancer cells. This finding may provide a rationale for the therapeutic use of antisense oligodeoxynucleotides targeted at basic fibroblast growth factor for the treatment of colon cancer.

Endoscopic treatment of colorectal benign-appearing lesions 3 cm or larger: techniques and outcome

PURPOSE

Colonoscopic polypectomy is the preferred technique to remove the majority of polyps. The authors evaluate feasibility, safety, and the effectiveness of endoscopic treatment of colorectal benign-appearing polyps equal to or larger than 3 cm.

METHODS

Ninety-seven patients with 104 giant polyps underwent polypectomy within a nine-year period. The majority of these procedures were performed on an outpatient basis, all on unsedated patients. Gross appearance, size, location, histologic characteristics, synchronous lesions, modality, and adequacy of removal of giant polyps were analyzed. The follow-up was achieved in 89 percent of patients during a period ranging from 6 to 96 months (median, 38).

RESULTS

Of the 104 removed polyps, 75 (72 percent) were adenomatous, 2 (2 percent) were hyperplastic, and 27 (26 percent) were malignant polyps. Six patients had more than one giant polyp. Several additional smaller polyps were found in 52 patients and a synchronous cancer in 4. Twenty-one (20 percent) giant polyps were equal to or larger than 4 cm. Forty-nine were pedunculated, 20 were short-stalked, and 35 were sessile. Sixty-one polyps were excised in one piece, and forty-three were excised using a piecemeal technique. Only four complications (3.8 percent) were recorded; all cases were treated endoscopically. Fifty-eight (75 percent) adenomas and eighteen (67 percent) malignant polyps were completely excised. Surgery was performed in 7 of 27 patients (27 percent) with malignant polyps, where there was a doubtful, infiltrated margin or poorly differentiated cancer. Postpolypectomy surveillance permitted the detection and treatment of 25 metachronous or recurrent polyps and a metachronous cancer.

CONCLUSIONS

This study shows that polypectomy of giant colorectal polyps, performed by an expert endoscopist, is feasible, effective, and safe, even on an outpatient basis. The authors confirm that malignant polyps with incomplete excision, lymphovascular invasion, and poor differentiation require bowel resection. Postpolypectomy surveillance is useful for all patients who have undergone colonoscopic resection of giant adenomatous or malignant polyps.

Frequency of advanced neoplasia in the proximal colon without an index polyp in the rectosigmoid

PURPOSE

Screening endoscopy has the potential to reduce colorectal cancer mortality. However, the efficacy of screening flexible sigmoidoscopy compared with colonoscopy strongly depends on the frequency of advanced proximal neoplasms without an index polyp in the rectosigmoid. We have therefore determined this frequency in our endoscopy population.

METHODS

Endoscopic and histologic data were analyzed from all patients on whom integral colonoscopy was performed between 1980 and 1995. Advanced neoplasia was defined as cancer or adenomas >10 mm in diameter, adenomas with a villous component, or severe dysplasia. Patients with polyposis syndrome or inflammatory bowel disease were excluded.

RESULTS

Colonoscopy was performed on 11,760 patients. 2,272 (19.3 percent) had at least one colorectal neoplasm, of which 39 percent had the neoplasm above the rectosigmoid. Twenty-two percent of all patients with neoplasia had no index polyp in the rectosigmoid and 16 percent of these had no index polyp, but at least one advanced proximal neoplasm.

CONCLUSIONS

Although 39 percent of patients had neoplasms above the rectosigmoid, only 16 percent had an advanced proximal neoplasm without an index polyp in the rectosigmoid. This gives a figure on which to base the evaluation of screening sigmoidoscopy programs against those of screening colonoscopy.