Malignant colorectal polyps: venous invasion and successful treatment by endoscopic polypectomy.

Abstract

We reviewed the pathology of 81 malignant colorectal polyps in 80 patients treated by endoscopic polypectomy and assessed the importance of carcinomatous invasion of veins in the stalk (submucosa). All the patients were followed up for at least five years. Venous invasion was present in 30 of the polyps (37%). The histological features oflymphatic invasion were considered too subjective to be of value. Most of the tumours were well or moderately differentiated adenocarcinomas, one was poorly differentiated, and one was a signet ring cell carcinoma. Seventy one patients were treated by polypectomy alone, and 58 of these were alive and well five years later, with no evidence of recurrence. Most adenocarcinomas of the colon and rectum arise in pre-existing adenomas.' In the early stages of malignancy there will clearly be an adenomatous polyp with a focus of invasive adenocarcinoma. Carcinoma is recognised in this situation when tumour has infiltrated through the muscularis mucosae into the submucosa. The lesion continues to show the morphology of a polyp -that is, a 'malignant polyp' -until a classical ulcerated invasive adenocarcinoma develops. ' The reported frequency of residual tumour or lymph node metastasis in patients with malignant colorectal polyps treated by endoscopic polypectomy lies between 0 and 15%.2-" Certain histological criteria are thought to be of prognostic importance, the most widely accepted being the grade of the carcinoma and the completeness of excision.' 4 6 8-11Several investigators have claimed that lymphatic and venous invasion are also important features, which independently determine metastatic potential in malignant polyps. 2 4 5 8 11 12 This has not been our experience at St Mark's Hospital, where endoscopic snare polypectomy is regarded as safe and effective treatment for malignant colorectal polyps provided the tumour is not poorly differentiated or incompletely excised.6 The aim of the present study, therefore, was to assess the prognostic importance of vascular invasion in a large series of patients with malignant polyps. MethodsFor this study a malignant polyp was defined as an adenoma, part or all of which was replaced by invasive adenocarcinoma. Those polyps in which there was no residual adenoma were termed polypoid adenocarcinomas. Invasion was defined as the infiltration of adenocarcinoma through the muscularis mucosae into the stalk (submucosa).The study material consisted of 81 malignant polyps removed from 80 patients between 1972 and 1984 at St Mark's Hospital. Seventy two of these were pedunculated and nine were sessile or broad based. The polyps were removed by snare polypectomy through an endoscope (73 polyps) or a rigid proctosigmoidoscope (seven polyps). A sessile malignant polyp in the rectum of one patient was excised surgically by submucosal resection (this patient also had a pedunculated rectal malignant polyp removed by snare polypectomy on the same occasion).Seventy two of the polyps were removed in one piece, and nine in two or more pieces. Th...

Histologic Risk Factors and Clinical Outcome in Colorectal Malignant Polyp: A Pooled-Data Analysis

“…In 23 series, [14][15][16][17][18][19][20][21][22][24][25][26][27]29,[31][32][33][34][35]38,[40][41][42] clinical or endoscopic follow-up data were available, ranging from 12 to 90 (median, 60) months, and accounting for 1,535 (80.1 percent) of the included polyps. Regarding endoscopic data, polyp site was clearly specified in 17 series, accounting for 1,461 polyps.…”

“…Regarding endoscopic data, polyp site was clearly specified in 17 series, accounting for 1,461 polyps. 14,[20][21][22]24,26,27,29,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]39 In such studies, the rectum was involved in 19.6 percent of the cases, the left colon in 71 percent, and the right colon in the remaining 9.4 percent. Polyp morphology was available in 19 series, enrolling 1,145 polyps.…”

“…Death because of surgical complications, inferred from 28 studies, was reported in 8 (0.8 percent) of 951 operated patients. [12][13][14][15][16][17][18][19][20][21][24][25][26][27][28][29][30][31][32][33][34][36][37][38][39][40][41][42] …”

“…[12][13][14][16][17][18][19]21,[27][28][29][30][31][32][33][34]37,[40][41][42] According to our protocol, the resection margin was reported to be positive in 325 (33.2 percent) and negative in the remaining 655 (66.8 percent) cases. In those studies for which polyp morphology also could be inferred, a positive resection margin was significantly more frequent in sessile (25/44) than in pedunculated (34/182) polyps (56.8 vs. 18.7 percent; P < 0.0001).…”

“…12,20,21,26,28,32,33,35 From 13 studies, it was apparent that the majority of patients with such a risk factor (56/60) underwent surgical resection compared with only 336 of the 739 without it (93.3 vs. 45.4 percent; P < 0.0001). 12,17,18,20,[26][27][28][29]33,37,38,41,42 In addition, patients with areas of poor differentiation had a substantially higher risk of both metastatic disease and cancer-related mortality compared with their counterparts (Table 1).…”