The significance of microscopic invasive cancer in endoscopically removed polyps of the large bowel. A clinicopathologic study of 51 cases

Tumor Budding Detection by Immunohistochemical Staining is Not Superior to Hematoxylin and Eosin Staining for Predicting Lymph Node Metastasis in pT1 Colorectal Cancer

BACKGROUND

Tumor budding is recognized as an important risk factor for lymph node metastasis in pT1 colorectal cancer. Immunohistochemical staining for cytokeratin has the potential to improve the objective diagnosis of tumor budding over detection based on hematoxylin and eosin staining. However, it remains unclear whether tumor budding detected by immunohistochemical staining is a significant predictor of lymph node metastasis in pT1 colorectal cancer.

OBJECTIVE

The purpose of this study was to clarify the clinical significance of tumor budding detected by immunohistochemical staining in comparison with that detected by hematoxylin and eosin staining.

DESIGN

This was a retrospective study.

SETTINGS

The study was conducted at Niigata University Medical & Dental Hospital.

PATIENTS

We enrolled 265 patients with pT1 colorectal cancer who underwent surgery with lymph node dissection.

MAIN OUTCOME MEASURES

Tumor budding was evaluated by both hematoxylin and eosin and immunohistochemical staining with the use of CAM5.2 antibody. Receiver operating characteristic curve analyses were conducted to determine the optimal cutoff values for tumor budding detected by hematoxylin and eosin and CAM5.2 staining. Univariate and multivariate analyses were performed to identify the significant factors for predicting lymph node metastasis.

RESULTS

Receiver operating characteristic curve analyses revealed that the cutoff values for tumor budding detected by hematoxylin and eosin and CAM5.2 staining for predicting lymph node metastases were 5 and 8. On multivariate analysis, histopathological differentiation (OR, 6.21; 95% CI, 1.16-33.33; p = 0.03) and tumor budding detected by hematoxylin and eosin staining (OR, 4.91; 95% CI, 1.64-14.66; p = 0.004) were significant predictors for lymph node metastasis; however, tumor budding detected by CAM5.2 staining was not a significant predictor.

LIMITATIONS

This study was limited by potential selection bias because surgically resected specimens were collected instead of endoscopically resected specimens.

CONCLUSIONS

Tumor budding detected by CAM5.2 staining was not superior to hematoxylin and eosin staining for predicting lymph node metastasis in pT1 colorectal cancer.

Management of T1 colorectal carcinoma with special reference to criteria for curative endoscopic resection

BACKGROUND AND AIM

In guidelines 2010 for the treatment of colorectal cancer from the Japanese Society for Cancer of the Colon and Rectum (JSCCR), the criteria for identifying curable T1 colorectal carcinoma after endoscopic resection were well/moderately differentiated or papillary histologic grade, no vascular invasion, submucosal invasion depth less than 1000 µm and budding grade 1 (low grade). We aimed to expand these criteria.

METHODS

A total of 499 T1 colorectal carcinomas, resected endoscopically or surgically, were analyzed. Relationships between clinicopathologic findings and lymph node metastasis were evaluated.

RESULTS

Lymph node metastasis was found in 41 (8.22%) of the 499 cases. The incidence of lymph node metastasis was significantly higher in lesions featuring poorly differentiated/mucinous adenocarcinoma, submucosal invasion ≥ 1800 µm, vascular invasion, and high-grade tumor budding than in other lesions. Multivariate logistic regression analysis showed all of these variables to be independent risk factors for lymph node metastasis. When cases that met three of the JSCCR 2010 criteria (i.e. all but invasion < 1000 µm) were considered together, the incidence of lymph node metastasis was only 1.2% (3/249, 95% confidence interval: 0.25-3.48%), and there were no cases of lymph node metastasis without submucosal invasion to a depth of ≥ 1800 µm.

CONCLUSIONS

Even in cases of colorectal carcinoma with deep submucosal invasion, the risk of lymph node metastasis is minimal under certain conditions. Thus, even for such cases, endoscopic incisional biopsy can be suitable if complete en bloc resection is achieved.

Proposed objective criteria for "grade 3" in early invasive colorectal cancer

To establish objective criteria for "grade 3" (G3) in T1 (TNM staging) colorectal cancer (CRC), a total of 296 T1 CRC cases were reviewed. The incidence of nodal involvement differed most greatly between G3 and non-G3 (21/27 [27%] and 6/162 [3.7%], respectively; P < .0001), when G3 was applied to tumors containing either or both of the following: (1) 10 or more solid cancer nests in the microscopic field of a 4x objective lens and (2) a mucin-producing component fully occupied the microscopic field of a 40x objective lens. Regarding G3, vascular invasion, and tumor budding as indicating the risk of metastasis, nodal involvement rate was 21.0% in the tumors with 1 or more risk factors, whereas it was only 1.7% in the no-risk tumors (P < .0001). In patients treated with local excision only, nodal recurrence occurred in 3 (20%) of 15 risk-positive patients, whereas none of 42 patients without risk factors had nodal recurrence (P = .016). In cases of locally excised T1 CRC, G3 as determined by the proposed criteria, vascular invasion, and budding would comprise a useful combination of parameters for determining the indication for additional laparotomy.

Poorly differentiated colorectal carcinoma with invasion restricted to lamina propria (intramucosal carcinoma): a follow-up study of 15 cases

Invasive colorectal carcinomas (CRCs) with invasion confined to the lamina propria (LP) [intramucosal carcinoma (IMC)] lack access to lymphatics and therefore have no potential for metastases and local intervention (usually polypectomy) should be adequate treatment. For this reason, they are classified as "Tis" in the TNM system. It is believed that carcinomas invading the submucosa with unfavorable histology (tumors at/near the margin, and/or vascular invasion, and/or poor differentiation) require additional intervention after polypectomy, whereas those with favorable histology can be safely treated endoscopically. However, there are few data on poorly differentiated (PD) carcinomas showing invasion confined to the LP. Polypectomy is theoretically curative but in practice this has not been well demonstrated. Thus, the clinicopathologic features of 15 cases of PD CRCs with invasion limited to the LP on initial biopsies were studied to determine the best course of management for this rare subset of carcinomas. A computer search and histologic review of cases seen at Johns Hopkins Hospital was performed. Fifteen cases of PD CRC with invasion limited to the LP were identified. The clinicopathologic features of these tumors were reviewed. All 15 cases showed PD IMC with single cells infiltrating only the LP. Patients were 38 to 79 years (median, 62) of age with a male predominance (M:F=4:1). Three cases had signet ring cell differentiation, 1 had focal small cell features, and another had focal squamous differentiation. Fourteen of the cases were associated with background adenomas or adenomalike lesions including: 7 involving tubulovillous or villous adenomas, 6 involving tubular adenomas, 1 involving dysplasia associated with chronic inflammatory bowel disease. Nine of the lesions had surrounding high-grade dysplasia. One case showed no background dysplasia or adenoma. One patient was lost to follow-up and the remaining 14 were followed for 1 to 96 months (mean, 21.3 mo; median, 13 mo). Seven patients had no residual disease on follow-up colonoscopy, and no resection was performed. The remaining 7 patients were treated with partial colectomy (6) or low anterior resection (1), and of these, 5 had no infiltrating carcinoma and negative lymph nodes. One patient had a separate large colorectal (T3) carcinoma with 8/10 positive regional lymph nodes; the IMC seen on biopsy was presumably a metastasis as it was unassociated with an in situ component. Finally, the resected rectum from which an IMC had been previously detected had no residual invasive carcinoma, but the anal skin was involved by Paget disease. Thus, of the 15 cases of PD CRCs limited to the LP, 1 was a metastasis from a separate CRC and another had associated Paget disease of the anal skin. As such, even in the setting of PD carcinomas, no metastatic disease was seen arising from any of the cases that were confirmed as early primary lesions. These preliminary findings suggest that patients with isolated intramucosal PD CRCs may be managed endoscopically.

The malignant colon polyp: diagnosis and therapeutic recommendations

This article discusses the proper handling of the malignant colon polyp, that is, polypoid lesions that appear endoscopically to represent adenomas and histologically reveal an invasive carcinoma component, from the time of endoscopy to the pathologic diagnosis. Prognostically important pathologic features and a paradigm to guide treatment decisions are presented.

Pathology of early lower GI cancer

Early colorectal cancer can be treated with curative resection if the depth of invasion is limited to the submucosa (pathologic T category pT1 in the TNM classification). Macroscopically early colorectal cancer and its precursor lesions present as elevated polyps or non-polypoid flat lesions. Microscopically, precursor lesions are characterized by intraepithelial neoplasia and present as classic adenomas or serrated adenomas. Precursor lesions may already contain foci of early colorectal cancer. Early colorectal cancer can be treated by endoscopic resection. Careful handling of the specimen is required in order to optimally identify the factors that may predict an adverse outcome. Whenever a favourable tumour grade is found, without vascular invasion and tumour budding, there seems to be a low risk for adverse outcome and laparotomy may thus be avoided.

Histologic risk factors and clinical outcome in colorectal malignant polyp: a pooled-data analysis

PURPOSE

The malignant polyp carries a significant risk of lymphohematic metastasis and mortality. Clinical usefulness of histologic risk factors is still controversial. The study was designed to compute the association between the main histologic risk factors and the occurrence of unfavorable outcomes in patients with malignant polyps.

METHODS

A MEDLINE search regarding malignant polyps was performed. Three histologic risk factors (positive resection margin, poor differentiation of carcinoma, vascular invasion) and five (residual disease, recurrent disease, lymph node metastasis, hematogenous metastasis, mortality) unfavorable clinical outcomes were evaluated. Further analysis was performed by subgrouping polyps in high-risk and low-risk groups.

RESULTS

Thirty-one studies enrolling 1,900 patients with malignant polyp were selected. Positivity of resection margin was significantly predictive of the presence of residual disease (odds ratio, 22; P < 0.0001), poorly differentiated carcinoma was associated with an increased mortality (odds ratio, 9.2; P < 0.05), and vascular invasion with a higher lymph node metastasis risk (odds ratio, 7; P < 0.05). Patients with high-risk polyps showed a significantly worse outcome than those with low-risk, especially for mortality (odds ratio, 11; P < 0.05). Surgical-related death was as low as 0.8 percent.

CONCLUSIONS

All three histologic risk factors are significantly associated with the clinical outcome. Classification in low-risk and high-risk patients may be regarded as a meaningful staging procedure.

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.

Pathologic prognostic factors in the recurrence of rectal cancer

For rectal cancer, local recurrence following surgical treatment is a grave complication that occurs in as many as 25% of cases. Pathological examination of the surgical resection specimen plays a primary role in assessing both the surgery- and tumor-related factors that contribute to the risk of recurrence. Among the tumor-related factors, stage has long been considered the single most accurate indicator of survival. However, recent evidence strongly suggests that the most powerful predictor of both local recurrence and overall outcome in the absence of distant metastatic disease is the macroscopic quality of the mesorectum in the resection specimen and the proximity of the tumor to the circumferential (radial) resection margin. Additional pathologic features have been shown to have stage-independent prognostic significance in colorectal cancer and may help to further define risk of adverse outcome. Such features include: tumor grade; histologic type; extent of extramural penetration by tumor; neural, venous, and/or lymphatic invasion; tumor border configuration; tumor budding; and host lymphoid response. The predictive value of tumor-specific molecular features is currently under investigation and may help to further improve prognostication and refine individual patient management in rectal cancer.

Long-term prognosis of well-differentiated adenocarcinoma in endoscopically removed colorectal adenomas

Thirty-six malignant polyps were identified that met the following criteria: well-differentiated adenocarcinoma and complete excision endoscopically. Location, type, size, distance of the cancer to the cautery mark, and lymphovascular involvement were analyzed to determine if they affected findings at surgery or risk of recurrent cancer. There were 20 patients and 21 polyps in the nonsurgical group, and 15 patients and polyps in the surgical group. One patient from each group had residual cancer after endoscopic removal of the polyp. The only factor that had an adverse effect on outcome was the distance of the cancer to the cautery mark (< 1 mm). Although rectal location was associated with the residual cancer, poor prognosis could have been predicted by the inadequate margins. This long-term follow-up (65 months average) study supports previous observations that an adequate margin is the most important factor in predicting the prognosis of endoscopically resected colorectal adenomas containing well-differentiated adenocarcinomas.

The pathologist and the residual tumor (R) classification

The R classification, adopted in 1987 by the UICC, denotes absence or presence of residual tumor after treatment. Residual tumor may be localized in the area of the primary tumor and/or as distant metastases. R0 corresponds to resection for cure or complete remission. R1 to microscopic residual tumor, R2 to macroscopic residual tumor. The R classification takes into account clinical and pathological findings. A reliable classification requires the pathological examination of resection margins. The R classification has considerable clinical significance, particularly being a strong predictor of prognosis. General and specific procedures for performing pathological R classification on resection specimens of different organs will be described. New methods in R classification comprise imprint cytology, cytolocial examination of ascites, examination of bone marrow biopsy. The importance of these methods will have to be established in the future.

Management of malignant colorectal polyps

The optimal management of patients with adenomatous polyps that contain invasive adenocarcinoma remains controversial. The independent factors of margins of resection, level of invasion, differentiation, grade, and vascular invasion are examined as prognostic indicators for outcome. The literature is reviewed with regard to the management of patients with polyp-containing invasive adenocarcinoma with standard operative resection versus endoscopic treatment alone.

The care of patients with colorectal polyps that contain invasive adenocarcinoma. Endoscopic polypectomy or colectomy?

BACKGROUND

The appropriateness of resection in patients from whom polyps with invasive adenocarcinoma were excised has been questioned.

METHODS

To determine the results of this policy, the authors reviewed the outcome of 42 patients from whom 44 such polyps were removed. Each polyp was categorized for the level of invasion according to the classification of Haggitt.

RESULTS

Level 1 invasion was found in 27%; level 2, in 9%; level 3, in 11%; level 4, in 39%; and uncertain, in 14%. The histologic grade was well differentiated in 48% of patients and moderately differentiated in 52%. No polyps contained poorly differentiated adenocarcinoma; lymphatic and vascular invasion were not encountered. Excision was judged complete in 23 patients; 11 underwent resection, and in none was residual adenocarcinoma identified. In 14 patients, margins could not be evaluated; of 12 patients who underwent resection, residual adenocarcinoma was found in 1. Of the seven patients with positive margins who underwent resection, residual adenocarcinoma was found in only two. In the resected specimens in which residual carcinoma was encountered, all original lesions were designated level 4. None of the patients treated by polypectomy alone has experienced a recurrence at a mean follow-up time of 66 months (range, 12-152 months).

CONCLUSIONS

The authors conclude that only patients with level 4 invasion require resection.

The value of nuclear morphometry in the management of patients with colorectal polyps that contain invasive adenocarcinoma

Haggitt's classification is a useful guide in the management of patients with large bowel polyps which contain invasive adenocarcinoma in that patients with levels 1 to 3 require no operation. Nuclear morphometry has been shown to be a useful prognostic discriminant for patients with invasive carcinoma of the large bowel. The nuclear shape factor of 44 polyps with invasive carcinoma was studied to determine whether this parameter was of value to define those patients with Haggitt level 4 who should have a resection. The shape factor of 50 interphase nuclei was obtained through the use of image analysis by tracing the nuclear profiles as digitized on a video screen. The nuclear shape factor was defined as the degree of circularity of the nucleus, a perfect circle recorded as 1.0. Our previous experience showed a nuclear shape factor greater than 0.84 was associated with a poor outcome. The overall mean shape factor was 0.71 (0.59-0.85). There was a tendency for the patients with residual disease to have values in the upper range. Our findings suggest that nuclear morphometry fails to add any predictive information in this clinical situation.

The risk of lymph node metastasis in colorectal polyps with invasive adenocarcinoma

One hundred fifty-one patients with colorectal polyps containing invasive adenocarcinoma treated by resection were studied to determine the incidence of lymph node metastasis and whether lymph node metastasis was related to the depth of invasion. Other variables evaluated included size and configuration of the polyp, grade of adenocarcinoma, presence or absence of lymphovascular invasion, and degree of differentiation. In patients with sessile polyps, the incidence of lymph node metastasis was 10 percent. Eighty percent of these lesions had lymphovascular invasion. For pedunculated polyps, the overall incidence of lymph node metastasis was 6 percent. However, there was no incidence of lymph node metastasis when the depth of invasion was limited to the head, neck, and stalk of the polyp (Levels 1, 2, and 3). Only when the depth of invasion reached to the base of the stalk (Level 4) was the risk of lymph node metastasis high (27 percent). The other risk factors were not associated with lymph node metastasis. We concluded that the most significant risk factor for lymph node metastasis in patients with invasive carcinoma in a polyp was invasion into the submucosa of the bowel wall (Level 4).

When is polypectomy sufficient treatment for colorectal cancer in a polyp?

Eighty-seven patients with a carcinoma in a polyp were reviewed over a 12-year period. Ten histologic criteria were analyzed for an association with the presence of residual carcinoma. Four factors were identified as having prognostic value: size greater than 1.5 cm, sessility, cancer of at least 50% of the adenoma volume, and invasive carcinoma. Polypectomy alone is adequate treatment unless the carcinoma invades deeper to the muscularis mucosa and is associated with one or more of these characteristics.

Colorectal adenomas containing invasive carcinoma. Pathologic assessment of lymph node metastatic potential

Adenomas that contain early invasive carcinoma (ACIC) represent the earliest form of clinically relevant cancer of the colorectum in most patients. In order to assess the incidence of nodal metastases of ACIC, we studied 31 patients in whom the colon was resected after endoscopic polypectomy (EP) done from 1975 to 1987. We also reviewed the pathologic features reported in individual cases and in literature series of ACIC with lymph node metastases published from 1958 to 1986. The lymph node metastatic potential of ACIC is relatively high, ranging from an average value of 8.5% in the literature of to 16.1% in our own study, and is equivalent to the range of 10%-17% that occurs in colorectal carcinomas that invade the submucosa. When an ACIC is seen in an EP specimen in which the polypectomy margin is normal, the decision as to whether the patient should enter a follow-up protocol or have radical surgical resection is determined by the assessment of the probability of the occurrence of nodal metastases. According to several authors, certain histopathologic features make it possible to distinguish between an ACIC with a high-risk of nodal metastases versus those with a low-risk. The most relevant pathologic parameters include the state of the resection margins, the grade of the invasive carcinoma, and the presence or absence of vascular invasion. Of 351 cases of ACIC that were operated on, derived from 16 literature series, 45.6% were high-risk cases and 8.5% had lymph node metastases. In our group of high-risk ACIC that had surgical resection subsequently, the lymph node metastatic rate was 35.7%. Our results help to estimate the nodal metastatic potential of early colorectal carcinomas and stress the importance of adequate pathologic evaluation in order to assess metastatic risk in these patients accurately.

Management of patients with invasive carcinoma removed by colonoscopic polypectomy

The management of patients with invasive carcinoma removed by colonoscopic polypectomy remains controversial. In order to assess the criteria for subsequent surgery after polypectomy, the histologic findings and outcome of 25 patients with invasive carcinomas treated by polypectomy were analyzed. Subsequent surgery was indicated when removed invasive carcinoma showed at least one of the following findings: 1) carcinoma near the surgical margin, 2) vessel invasion, 3) massive invasion, and 4) poorly differentiated adenocarcinoma. The authors considered those findings to be a risk factor for local residual carcinoma or lymph-node metastases, or both. Of 25 patients, 18 showed risk factors, with 16 receiving surgery. Only one had residual carcinoma in the lymphatic vessel of the surgical specimen. The remaining 15 had no carcinoma in the surgical specimens, however, one died of recurrent disease 55 months later. Two patients with risk factors received no surgery for various reasons. Local recurrent carcinoma developed in one 39 months later and the other had no recurrent carcinoma at autopsy. Seven patients without risk factors were adequately treated by polypectomy without recurrent disease 34 to 96 months later (average, 69 months). Consequently, of 18 patients with risk factors, 3 showed either residual carcinoma in the surgical specimens or recurrent carcinoma was found later. None of 7 patients without risk factors developed recurrent disease. We recommend that patients with risk factors be followed by surgery; however, patients without risk factors can be adequately treated by polypectomy alone.

Large bowel adenomas containing carcinoma--a diagnostic and therapeutic approach

Adenomas containing invasive carcinoma of the large bowel form the majority of early colorectal cancers. Conclusive histological diagnosis of early colorectal cancer depends on two conditions; first, the whole lesion must be examined and second the resection margin must border on healthy tissue. The presence of certain histopathological features makes it possible to distinguish between cases with high and low risk of having lymph node metastases. Sixty-six adenomas containing invasive carcinoma are reported. They comprised 3.15% of 2,095 adenomas removed by colonoscopic polypectomy during the same period. Five cases were lost to follow-up. Forty-nine patients considered to be at low risk of having lymph node metastases have been treated by endoscopic polypectomy only with a rigorous follow-up regime including CEA estimation, ultrasonography and total colonoscopy at regular intervals. In none have distant metastases been found on follow-up examinations at a mean duration of 3 years. Two of these cases have developed a metachronous colorectal carcinoma and 15 (30.5%) have metachronous adenomas. Two low risk patients with no tumour found in the operative specimen have undergone major surgical resection. Ten high risk cases have been referred for major surgery and lymph node metastases have been found in four (40%). The need for careful histological examination for lymphatic and veinous invasion is stressed by the presence of this finding in all four high risk patients with involved lymph nodes.

Endoscopic treatment of colorectal carcinoma

All malignant pedunculated polyps of the colon can be removed totally by colonoscopy alone. Resection of the colon is only necessary in those few instances where the cancer portion is poorly differentiated and where there are cancer cells in lymphatic or vascular channels. Malignant well differentiated sessile polyps are adequately managed by the endoscopic technique as well if the polypectomy is believed to have been complete and this can be confirmed by follow-up biopsies after 4-8 weeks. In these patients Laser therapy may also be of value. Endoscopic Laser therapy may be of value as a symptomatic treatment in patients with advanced malignant disease with obstruction or bleeding.

Small colonic adenomas with adenocarcinoma. A retrospective analysis

The purpose of this study is to alert colonoscopists to a relatively high incidence of small colonic adenomas with invasive adenocarcinoma among a group of colonic adenomas with invasive adenocarcinoma removed colonoscopically. Retrospective analysis (1973 to 1983) documented nine such lesions that were 1 cm or smaller, representing 15 percent of all colonic adenomas with invasive adenocarcinoma removed during that period. These lesions had no distinctive gross features and could be easily confused with hyperplastic polyps. It is recommended that all colonic polyps be removed at colonoscopy regardless of their size, because even lesions 1 cm and smaller, with "benign" gross appearance, may harbor invasive adenocarcinoma.

Management of endoscopically removed malignant colon polyps

The medical records of 87 patients with 89 malignant colorectal polyps removed endoscopically between 1971 and 1983 were reviewed retrospectively. Fifty-five polyps contained carcinoma-in-situ. Four polyps had "pseudo-invasion" by displaced mucosal glands. Thirty polyps contained invasive carcinoma. No patients with carcinoma-in-situ or "pseudo-invasion" had either local residual disease or metastatic disease at the time of colectomy or which was detected during subsequent follow-up. Four patients (14%) with invasive cancer would have been inadequately treated by polypectomy alone, since one had residual disease at the polypectomy site, one had nodal metastases, one had liver metastases at the time of colectomy, and one subsequently developed liver metastases. Three histologic criteria correctly predicted all four cases where residual or recurrent disease was present: involvement of the polypectomy resection margin, lymphatic invasion within the polyp, and poorly differentiated histology. Polyp size, histology (villous adenoma, adenomatous polyp, or villo-adenomatous polyp), or anatomic location did not identify those patients who warranted further therapy. We conclude that polypectomy alone is adequate treatment for polyps containing carcinoma-in-situ. Polypectomy alone is also adequate treatment for most polyps containing invasive carcinoma. However, patients with lymphatic involvement within the polyp, poorly differentiated cancer, or resection margin involvement should probably undergo colectomy.

Patient management after endoscopic removal of the cancerous colon adenoma

The subject of management of patients after endoscopic removal of cancerous adenomas is controversial. A retrospective review of 126 lesions in 121 patients who had had colonoscopic polypectomy of malignant lesions between 1971 and 1985 was used to determine the criteria for colon resection. Invasive cancer was identified in 80 patients, while 41 patients had carcinoma in situ. A synchronous colon cancer was found in five of the 121 patients. The patients who had carcinoma in situ had no evidence of residual tumor or metastatic disease on subsequent follow-up (colon resection in three patients and endoscopic surveillance in 38 patients). Of the 80 patients with invasive cancer, 44 had subsequent colon resection, and 34 of these had no evidence of tumor in the resected bowel or mesenteric lymph nodes. Ten patients had residual tumor, metastatic cancer to regional lymph nodes, or both. Each of the 10 had at least one of the following indications of inadequate resection or dissemination of disease to local lymph nodes (the first indication is a macroscopic evaluation, while the remaining four are all microscopic): incomplete excision, poorly differentiated tumor, invasion of the line of resection, invasion of the polyp stalk, and invasion of venous or lymphatic channels. Present recommendations for patient management after endoscopic removal of an invasive malignant adenoma should include colon resection with regional lymphadenectomy for patients with one or more of these five criteria. Patients without any of these risk factors should have early repeat endoscopic examination 3 months after initial polypectomy to evaluate the polypectomy site. Total colonoscopic examination is repeated at 1 year to ensure the surveillance program is begun with a colon without neoplasms.

Early invasive cancer in adenomatous colonic polyps ("malignant polyps"). Evaluation of the therapeutic options by decision analysis

The management alternatives of segmental colonic resection versus follow-up alone for colonic adenomas containing early invasive carcinoma (i.e., polypectomy resection margin free of tumor) were evaluated by decision tree analysis. Using data from the literature, the major variables influencing the decision were as follows: probability of residual disease after polypectomy, operative efficacy (defined as the chance of curing a tumor that would otherwise recur without surgery), and operative mortality. For a hypothetical patient with low operative risk (operative mortality of 0.2%), resection would yield the best outcome in terms of life expectancy as long as the probability of residual disease was greater than 0.5%. Extensive analysis of the impact of changes in assumptions about the parameters characterizing the problem showed this conclusion to be unchanging over wide ranges of operative efficacy and probability of residual disease. However, the decision to do a secondary resection in this situation was still close because surgery was only marginally justifiable on economic grounds. Observation would be preferred in patients with higher operative risk (operative mortality greater than 2%).

Colorectal polyps: an endoscopic experience

Between April 1975 and December 1985, 870 colonoscopies were performed and 803 colorectal polyps were managed endoscopically. Thirty-nine per cent of the polyps were metaplastic polyps. The majority (59%) of polyps less than 5 mm in diameter were metaplastic polyps. Of the adenomatous polyps 63% were tubular, 32% were tubulovillous and 5% were villous histologically. Sixty-two per cent of all polyps were found in either the sigmoid colon or rectum. There was a higher proportion of tubulovillous adenomata (32%) than reported previously. Twenty-two patients had polypoid carcinomata and eight were removed endoscopically; four were subsequently referred for surgical excision because of 'incomplete' removal but no residual tumour was found. Fifty-three per cent of patients examined had more than one polyp. Fourteen of 19 patients who presented with a single polyp were found to have further polyps when examined subsequently and 29 of 39 patients with multiple index polyps had more polyps at follow-up. Perforation occurred in three patients, and two patients required blood transfusion following endoscopic polypectomy. It is suggested that total colonoscopy should be undertaken in all patients with polypoid disease because of the distribution of polyps found. It is further suggested that the findings of this study may be related to the high incidence of colorectal carcinoma in New Zealand.

When is endoscopic polypectomy adequate therapy for colonic polyps containing invasive carcinoma?

We correlated the histopathology with outcome for all patients with endoscopically removed colonic polyps containing invasive adenocarcinoma seen at our institution over a 10-yr period. Invasion was defined as infiltration of malignant cells into the submucosa. Of a total of 1523 adenomatous polyps, 41 polyps (2.7%) in 39 patients contained invasive adenocarcinoma. One patient was excluded from further analysis because of a synchronous colonic carcinoma. Fourteen patients (37%) had favorable histologic features (grade I or grade II carcinoma with free margin of resection and absence of lymphatic invasion), and none developed metastatic carcinoma during the follow-up period (mean 6.5 yr, range 4-10.6 yr). Twenty-four (63%) had unfavorable histologic features (grade III tumor with tumor at or near the margin of resection or lymphatic invasion), and 10 of these (42%) had either residual local or metastatic carcinoma in subsequent operations or during the follow-up period. This difference in outcome was statistically significant (p less than 0.05) when compared with the outcome of the group with favorable histology. We conclude that endoscopic polypectomy is adequate therapy for colonic polyps containing invasive carcinoma, provided that the favorable histologic features are present.

Colorectal adenomas. Distribution, incidence of malignant transformation, and rate of recurrence

In 282 patients, 731 colon polyps (643 adenomas and 88 hyperplastic polyps) were extirpated endoscopically or biopsied and investigated histologically. Localization of the adenomas with various degrees of atypia and the hyperplastic polyps, as well as their size distribution, were determined. In 66 patients with adenoma polypectomy on the first examination, one or more control colonoscopies were carried out (in all, 107). The median period of follow-up observation was 31 months. Thirty percent of the one-year control colonoscopies after polypectomy revealed new adenomas. The statistical analyses showed that patients with singular adenomas, on initial investigation, develop significantly fewer adenomas in the further course than patients with multiple initial findings, especially in negative results in the one-year control. The size of new adenomas found during the first 24 months after polypectomy does not exceed 10 mm. On the basis of these results and the literature data available so far, a follow-up program is presented for discussion.

The significance of synchronous carcinoma and polyps in the colon and rectum

The relationship of colorectal carcinoma with polyps was studied retrospectively in 1202 patients. The incidence of synchronous carcinoma (SC) and metachronous carcinoma (MC), prognosis, and recurrence patterns were studied. Synchronous polyps (SP) were found in 36% of the patients. SC was found in 4.4% of the patients, and MC developed in 3.5% of patients. The incidence of SC and of MC increased with SP, and varied according to number, size, and histologic features of the polyps. The adjusted 5-year survival rate was improved in patients with SP compared with those without SP, both overall (79% versus 64%, respectively) and by Dukes' Stage B (87% versus 73%, respectively) and Dukes' Stage C (56% versus 39%, respectively). The pattern of relapse was the same for the SP and non-SP groups. Subtotal colectomy is recommended for colorectal carcinoma and SP in good-risk patients.

An appraisal of endoscopic removal of malignant colonic polyps

The issue of whether patients who have invasive carcinoma in an otherwise benign polyp should undergo surgical resection of that bowel segment is controversial. We examined the records of 83 patients with such polyps that were removed endoscopically between 1978 and 1981. After exclusion of 18 patients from the study for various reasons, our study group consisted of 65 patients who had undergone complete endoscopic removal of 69 polyps that contained a malignant process. Carcinoma in situ was found in 34 polyps, and 3 patients with such polyps had a recurrent malignant lesion of the same degree. These recurrent tumors were treated successfully by aggressive endoscopic removal. Seventeen polyps that contained invasive carcinoma were treated endoscopically without resection, and two patients in this group subsequently had recurrent carcinoma at the site of the original polyp. These recurrent lesions were resected, and neither patient had evidence of nodal metastasis. Of the 18 patients who underwent immediate resection of invasive carcinoma, 2 had residual carcinoma at the time of the resection, although no lymph node metastasis was found. We conclude that colonic polyps with carcinoma in situ can be treated safely with complete endoscopic removal. Invasive carcinoma in a polyp can be treated safely with complete polypectomy, and immediate resection may not be necessary. This group of patients, however, should undergo thorough follow-up studies and periodic endoscopic reexamination.

Early invasive carcinoma in colonic polyps. A review of the literature with emphasis on the assessment of the risk of metastasis

The proper treatment of adenomatous colonic polyps containing small foci of invasive cancer is controversial because the metastatic potential of these lesions is not precisely known. This article critically reviews all known English language studies of this lesion. Before the introduction of colonoscopic polypectomy, the estimated incidence of metastasis from this lesion was 10.4% (based on 12 studies containing 347 polyps), with a confidence interval (95% level) of 7.4 to 14.1. The incidence of metastasis estimated from lesions removed via colonoscopic polypectomy was 10.1% (based on 13 studies containing 188 polyps), with a confidence interval of 5.9 to 14.8. Differences in the definitions of the involved lesions, study designs, and indications for resection cause problems with case selection bias and make comparison of studies difficult. These problems are discussed in detail. Most studies had broad confidence intervals for the estimated incidence of metastasis because of small sample size. The histopathologic criteria, as reflected in the literature, for considering polypectomy alone as adequate treatment for this lesion are summarized and discussed.