Hiromi Shinya

Morphology, Anatomic Distribution and Cancer Potential of Colonic Polyps: An Analysis of 7,000 Polyps Endoscopically Removed

The concept of a polyp-cancer sequence is assuming increasing credibility as a factor in the development of colorectal cancer. Colonoscopy permits most colonic polyps to be endoscopically removed and studied pathologically. Of various polyp types encountered in the colon only neoplastic polyps are regarded as having malignant potential. Neoplastic polyps include tubular adenomas (formerly, adenomatous polyps), villous adenomas and villotubular adenomas (formerly, mixed or tuboglandular polyps). Cancerous changes must penetrate the muscularis mucosae for a polyp to be regarded as clinically malignant. The present report analyzes a series of 5,786 adenomas from over 7,000 polyp endoscopically removed. The largest number of each type of adenoma presented in the sigmoid colon, followed by the descending colon in terms of frequency. In all zones tubular adenomas were most common, villous least. Abnormal cellular change, from dysplasia to carcinoma in situ to invasive cancer was most frequently found in the sigmoid colon and, in all colon sectors, increased as the villous componency of the polyp increased. However, all categories of neoplastic polyps showed malignant changes. Polyp size, long recognized as a factor, was shown to be importantly related to malignant change, but invasive cancer was found even in polyps less than 1 cm in diameter. In addition, the incidence of malignancy rose parallel to the frequency of synchronous and metachronous polyps. A vigorous program for detection and endoscopic removal of colorectal polyps is recommended as a means of reducing the incidence of colorectal cancer.

Polypectomy via the fiberoptic colonoscope. Removal of neoplasms beyond reach of the sigmoidoscope.

Abstract Polyps of the colon and rectosigmoid, potentially precancerous lesions, have heretofore required laparotomy and colotomy for removal. Against a background experience of 1600 fiberoptic colonoscopies without complication a program in endoscopic removal of colonic polyps from all parts of the colon was undertaken. Three hundred and three polyps, 0.5 to 5.0 cm in diameter, were safely removed by this technic. Bleeding, controlled by transfusion therapy, occurred, in one patient, and minor bleeding in four others.

Endoscopic gastroduodenal polypectomy

During a 6-year period from 1976 to 1982, 7346 gastrointestinal endoscopy procedures were performed in the Surgical Endoscopy Unit of Beth Israel Medical Center. This report summarizes our experience with 443 gastroduodenal polyps excised in 257 patients. Of these, 123 were male and 134 female, ranging in age from 19 to 92. The vast majority were between the ages of 60 and 80. With one exception, polyps varied from 0.3 cm to 6 cm in diameter (one patient had a 12-cm hyperplastic polyp). There were 399 gastric polyps in 238 patients and 44 duodenal polyps in 19 patients. Of the polyps excised, 282 (63.1%) were sessile and 161 (36.9%) were pedunculated. The majority of the patients (185) had a single polyp and 72 patients had two or more polyps. Seven patients with multiple polyps had Peutz-Jeghers Syndrome and two patients had Gardners Syndrome. Hyperplastic polyps constituted the majority (62%) of the polyps. These polyps have minimal, if any, tendency to degenerate into carcinoma. In contrast, adenomatous gastroduodenal polyps (21%) have a definite propensity to degenerate into carcinoma. This occurred in 9.6% of the patients in this series. There were no deaths and only two complications (bleeding) in this series.

Tissue culture of human epithelial cells from benign colonic tumors

SummaryHuman colonic epithelial cells from three classes of benign tumors have been reproducibly cultured free of fibroblasts for 8 wk using a supplemented Medium 199 (M 199S). The cultured colonic cells were identified as epithelial by the presence of junctional complexes (tight junctions, gap junctions, and desmosomes), a brush border on the apical surface, keratin fibrils, and by both a close-packed columnar or cuboidal morphology and the capability to transport water and ions to form hemicysts. Colony formation was initiated by groups of epithelial cells, not by single cells, and was inhibited by cocultivation with either lethally irradiated 3T3 cells or human diploid fibroblasts. Enhancement of epithelial colony formation was observed following culture on nonadherent, “floating” substrates compared with substrates attached directly to the bottom of the culture dish.Replication of epithelial cells in M 199S from the class of benign colonic tumors least prone to malignancy, the tubular, was significantly enhanced by epidermal growth factor (EGF). In contrast, EGF did not stimulate the growth of cells in M 199S from the other classes of benign tumors, the villotubular and the villous, which exhibit more malignant potential. These data imply that premalignant colonic epithelial cells lose responsiveness to growth modulation by EGF as they progress toward frank carcinoma.

Colonoscopic diagnosis and management of rectal bleeding.

The use of the colonoscope to evaluate the cause of rectal bleeding in a series of 2200 patients has been reviewed. The most common cause of bleeding in this series was found to be neoplastic polyps, which were present in 723 patients (32 per cent). Colonic carcinoma was detected as the source of the bleeding in 425 cases (19 per cent). Although a large number of barium enema films were false negatives, the patients reviewed are a highly select group. It is still believed that barium enema studies and colonoscopy are complementary rather than competitive procedures. Their continued combined use greatly enhances diagnostic accuracy. Various other causes of colonic bleeding, including inflammatory bowel disease, arteriovenous malformations, endometriosis, ovarian carcinoma, ischemic colitis, and radiation colitis, have been discussed and their endoscopic appearance described. Of particular significance is the coexistence of internal hemorrhoids or diverticular disease and neoplastic colonic lesions. Barium enema films and sigmoidoscopy have been frequently described as the twin pillars of diagnosis in the detection of colonic pathology. Colonoscopy, as the third pillar of diagnosis, should be an integral part of the evaluation of patients with rectal bleeding.

Primary linitis plastica of the colon and rectum. Report of two cases.

Primary linitis plastica of the colon and rectum is an uncommon entity. Sixty-six cases have been reported in the English literature. Two new cases are reported, one of the transverse colon with widespread metastases and the other of the right colon extending from the appendix to the distal resection margin of the transverse colon. Some clinical and pathologic characteristics of the tumor are discussed, based on a review of the literature.

Earlier diagnosis of cancer of the colon through colonic endoscopy (colonoscopy).

Colonoscopy is a major advance in the diagnosis, treatment, and investigation of diseases of the colon and rectum, particularly cancer. Based on our early experience, this technique can be expected to bring malignant and premalignant lesions of the large intestine to clinical attention at an earlier stage and thus effect a higher cure rate. The large majority of colonic polyps can be removed from all levels of the colon safely by the endoscopic route, eliminating the need for laparotomy in most cases and reducing costs of care materially. Errors in radiologic diagnosis, positive, negative, or equivocal, can be materially reduced when there is endoscopic confirmation. Thus, colonoscopy and the contrast enema may be regarded as complementary studies. Colonoscopy is an extremely safe method of study when carried out in expert hands; it can be done on an ambulatory basis. There is an urgent need for good training programs to ensure adequate availability of the method to the public. The technique is also an excellent means of followup for patients who have been treated for cancer, polyps, or inflammatory diseases of the colon and rectum. Pertinent and illustrative case material gleaned from a clinical experience of over 4000 colonoscopies and 600 endoscopic polyp removals is presented.

Colonofiberscopic management of colonic polyps

ConclusionsEndoscopic removal of 343 colonic polyps more than 0.5 cm in size, located from the cecum to the sigmoid colon and beyond the reach of rigid sigmoidoscopes, is reported.Diagnostic colonofiberscopy is a valuable procedure permitting direct visual examination of the entire colon with a high degree of safety. More than 1,800diagnostic colonofiberscopies have been performed in our unit without a single complication.The polypectomy procedures via the colonofiberscope were done without mortality and with only a single immediate complication, which responded to conservative measures. Endoscopic removal of colonic polyps is proposed as a safe, practical alternative to either laparotomy and colotomy or repeated barium-enema studies in the management of the patient with a colonic polyp. The endoscopic approach allows differentiation of malignant from nonmalignant polyps by complete excision, thus permitting definitive cancer therapy measures to be undertaken promptly and with assurance.Endoscopic removal of colonic polyps is not advised for endoscopists who have not first achieved considerable experience and dexterity in diagnostic colonoscopy. Endoscopic removal of colonic polyps is best accomplished by an experienced endoscopist supported by the full spectrum of general hospital resources, after the patient has been thoroughly evaluated medically. It should be carried out on an inpatient basis.When a patient has a colonic polyp, an alert should be maintained for unsuspected colonic cancer unrelated to the polyp, lest the less serious lesion monopolize the clinical situation.

Endoscopic polypectomy Therapeutic and clinicopathologic aspects

The problem of the malignant potential of neoplastic colonic polyps is being, in large measure, resolved by newly derived techniques. Now most polyps may be removed endoscopically using the fiberoptic colonoscope. The largest world experience is at the Beth Israel Medical Center in New York, where over 2000 polyps have been endoscopically removed without a single death and with but one complication requiring operative intervention. Laparotomy is now reserved for polyps not suitable for endoscopic resection or where a question of residual cancer exists. Experience with endoscopic resection has called for: 1) re‐assessment of colonic polyps in terms of their malignant potential; and 2) clarification of the indications for laparotomy and bowel resection subsequent to or instead of endoscopic removal. Among all polypoid lesions 0.5 cm or greater in size in the Beth Israel series, a variety of pathologic types was encountered. If only the neoplastic polyps were considered, the incidence of “malignant change” was 10.5% for 855 polyps analyzed. There is, however, a need to clarify terminology and to differentiate between carcinoma in situ and invasive cancer whenever possible. Superficial cancers (carcinomas in situ) do not recur or metastasize and require no treatment other than polyp removal. When “invasive” cancer is present (4.5% of neoplastic polyps) or the lesion is a “polypoid carcinoma” each case must be individually evaluated. Criteria for diagnosis, gross morphological features suggesting cancerous change, and current management of “malignant” polyps are discussed. Colonoscopy is an important component of the followup program whether malignant polyps are resected endoscopically or by the transabdominal route.

A Rationale for the Endoscopic Management of Colonic Polyps

The incidence of invasive cancer in colonic polyps is related to the size of the lesion and the histologic type of the adenoma. It is greatest for villous adenomas and least for tubular adenomas. The malignant potential increases with the size of the polyp, and in lesions 3 cm and larger malignant disease is present in at least 12 per cent. In general, polyps with invasive malignant disease require colon resection, but for pedunculated adenomas, colonoscopic polypectomy is adequate treatment. Even when invasive cancer is close to the line of endoscopic resection but does not invade the stalk or does not display lymphatic or vascular invasion, a case may be made for conservative, endoscopic treatment alone because the occurrence of local or distal metastasis is very unusual.