Definitive Treatment of “Malignant” Polyps of the Colon

Abstract

There has been an unremitting rise in incidence of colonic cancer in this country with no recent improvement in cure rate. As a result the evolution of colorectal cancer has been the focus of considerable attention with an enlarging body of evidence pointing to the common neoplastic polyp as a precursor to malignancy. "Neoplastic" polyps include "adenomatous polyps," "villous adenomas" and, lately recognized, "villo-glandular polyps." Experience with endoscopic removal of over 2,000 colonic polyps (with no mortality) has introduced two questions of prime concern to the surgeon: (1) What constitutes clinical malignancy in a polyp? AND, (2) When should laparatomy supplant or follow endoscopic removal? Eight hundred and ninety-two consecutive adenomatous (tubular), villous, villoglandular (villo-tubular) and "polypoid cancer" polyps are analyzed, 855 of which have been followed for 6 months to 4 years. Support is offered to the concept that villous and tubular growth patterns are merely variants of a similar base disturbance in cell renewal. Superficial cancer (carcinoma-in-situ) occurred in 6.6% of neoplastic polyps and represents no threat if the polyp is completely removed. Only when the cancer penetrates the muscularis mucosae should it be regarded as "invasive." The term "malignant polyp" should be reserved for this form. Invasive cancer was found in 5.0% of neoplastic polyps in this series. Only in this group need the question of further surgical intervention be raised. Major considerations influencing a decision for subsequent laparotomy are polyp size and gross morphology (i.e. sessile or pedunculated), histologic type (of the polyp and of the cancer itself), adequacy of clearance between depth of invasion and plane of polyp resection, and the patient's age and general condition. These are analyzed. Twenty-five of 46 patients with "malignant polyps" were subjected to abdominal exploration: 17 showed no residual cancer, whereas 8 (5 with recognized incomplete endoscopic removal) had tumor in the bowel wall. Of the remaining 21 patients, for whom endoscopic polypectomy alone was deemed appropriate, none have shown residual or recurrent cancer on clinical and endoscopic followup. Colonoscopy appears to be a most promising approach in terms of the goals of cancer programs, offering both prophylaxis and opportunity for treatment at a favorable stage of disease.

The Malignant Polyp - When to Operate: The St. Mark’s Experience

“…Besides incompleteness of excision and high grade carcinoma, vascular invasion by carcinoma into the stalk or submucosa is considered by some authors to confer increased risk of recurrence (2,LS,24,26,34). The evidence for this is poor, due to small numbers and the frequent confounding factors of high grade tumour or incomplete excision.…”

“…The advent of flexible colonoscopy and the ability to remove polyps (including polyps with invasive carcinoma) anywhere in the colon inevitably resulted in the application of similar criteria to malignant colonic polyps. By 1975 Wolff and Shinya (2), on the basis of the histopathological expertise of Riddell and Morson (J) and their already considerable experience of colonoscopic polypectomy, gave a 'seal of approval' co the principle of conservatism in the management of malignant polyps. Since then a large number of ocher clinical series have supported this approach (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), as have editorials (20,21) and review articles (15,22,23 ).…”

“…Such support for a nonoperative policy coming from experienced colorectal surgeons, endoscopists and surgical groups such as those of Christie (10), Shinya (2) or St Mark's should encourage others tending coward the 'knee-jerk surgery' approach to think again. Since the matter can only be proved conclusively by large scale controlled trials, which would be difficult to achieve in view of the relative infrequency of polyps, a reasonable compromise is for all centres to publish their long term follow-up results, which too few have done.…”

Variabilidade interobservador no diagnóstico histológico dos pólipos colorretais

“…Em um estudo da Cleveland Clinic, onde foram avaliados 1523 pólipos adenomatosos, foram encontrados 41 casos de carcinomas invasivos (2,7%), o que se assemelha aos resultados desta pesquisa 21 . Outros autores relataram a presença de carcinoma invasivo em 0,2-8,3% dos pólipos [29][30][31] . Neste estudo, obteve-se uma grande variabilidade quanto ao tipo de diagnóstico, se for mencionado o Kappa nas comparações interobservadores, pois este variou de 0,000 a 0,798, ou seja, de ausente a modera- do.…”

Role of colonoscopy in colorectal cancer

“…Reports of lymph node metastasis for in situ or intramucosal carcinomas are anecdotal 61 . Therefore, for lesions with clear histologic margins, complete resection by endoscopy remains a sufficient curative treatment 44,62,63 .…”