Approach to a colorectal polyp

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1 /2003/95/9/ REVISTA ESPAÑOLA DE ENFERMEDADES DIGESTIVAS Copyright 2003 ARÁN EDICIONES, S. L. REV ESP ENFERM DIG (Madrid) Vol. 95. N. 9, pp , 2003 GUIDE OF CLINICAL PRACTICE Approach to a colorectal polyp R. Muñoz Gómez, M. L. Manzano Alonso and J. A. Solís-Herruzo Digestive Medical Service. Hospital 12 de Octubre. Madrid, Spain Muñoz Gómez R, Manzano Alonso ML, Solís-Herruzo JA. Approach to a colorectal polyp. Rev Esp Enferm Dig 2003; 95: Received: Accepted: Correspondence: R. Muñoz Gómez. Digestive Medical Service. Hospital 12 de Octubre. Ctra. de Andalucía, km. 5, Madrid, Spain. Phone: Fax: applemans@yahoo.com Polyps are defined as well delimited lesions that protrude in the intestinal lumen from the mucosa. From a morphological point of view, they may be sessile or pedunculated. They are presented as isolated, multiple or diffuse lesions. The appearance of multiple or diffuse lesions characterize polyposis syndromes, which are hereditary and constitute well-defined entities that exceed the purpose of this review (1). Colorectal polyps are classified as neoplastic (adenomatous) and non-neoplastic. n-neoplastic polyps do not have malignant potential and include hyperplastic, hamartomas and inflammatory polyps. Once they have been removed and histologically analyzed, these types of polyps do not require endoscopic follow-up. Adenomas are a result of the abnormal proliferation of the epithelium of the intestinal mucosa, for which they have malignant potential. Adenomas are classified as tubular, tubulovillous or villous, depending on the presence and grade of the papillary component. Approximately 70% of the polyps surgically removed by colonoscopy are adenomas (2). Of these, 70-85% correspond to tubular adenomas, 10-25% to tubulovillous adenomas and less than 5% to villous adenomas. At present, the adenoma-carcinoma sequence is fully accepted. The National Poly Study Workgroup (3) established that the adenoma or adenomatous polyp is a premalignant lesion that precedes, in most cases, the appearance of colorectal cancer (CRC); therefore, excision of the adenoma reduces or even eliminates the risk of developing this tumor. Colonoscopy is considered the most efficient strategy for CRC prevention. The low and high-grade dysplasia classification (4) reduces the interobserver variation. High-grade dysplasia includes the term in situ, intramucous carcinoma or focal carcinoma. At the time of diagnosis, 5-7% of the patients with adenomas present high-grade dysplasia and 3-5% invasive carcinoma. The degree of dysplasia and presumably the malignant potential increase with the size of the polyp (>1 cm), the villous component and age of the patient (>60 years old) (4). The diagnosis of colonic polyps is usually incidental during an examination of the colon and rectum. On other occasions, polyps are detected in CRC prevention programs or during follow-up of patients with colorectal neoplasias. In a small percentage of the cases, they are presented as small quantity rectorrhages or ferropenic anemia. Large size rectal polyps may protrude through the anus during defecation. Colonoscopy enables identification of the number, size and location of the polyps and in most cases their immediate and complete resection. Nevertheless, it is important to keep in mind that 27% of the adenomas smaller than 5 mm, 13% of the lesions that measure between 6 and 9 mm and 6% of the polyps exceeding 1 cm are missed during colonoscopy (5). If total colonoscopy is not possible (5-10% of the cases) (6), an acceptable alternative is to perform a rectosigmoidoscopy and double-contrast barium enema. The double-contrast barium enema demonstrates the presence of polyps, although up to 52% of the polyps of the same size or larger than 1 cm (7) may not be detected. The limitations of this examination are the impossibility of carrying out a polypectomy and its relatively low specificity. Magnifying colonoscopy consists in the use of endoscopes that magnify up to 100 times the real size of the image, which helps distinguish between adenomatous

2 646 R. MUÑOZ GÓMEZ ET AL. REV ESP ENFERM DIG (Madrid) and hyperplastic polyps and even determine the presence of invasive cancer (8). Virtual colonoscopy by tomography or nuclear resonance offers promising results, however its general application is not presently considered (9). A complete colonoscopy to remove the polyps and rule out the existence of synchronous lesions should be carried out in patients in whom polyps have been detected in the barium enema or by a rectosigmoidoscopy, since 23-40% of the patients that present polyps in the left colon also evidence polyps in the proximal portion of the colon (10,11). Endoscopic resection is the choice technique for the treatment of polyps. Perforation and hemorrhage are the main complications of polypectomy, with an incidence below 2% (12). In large sessile polyps, the injection of saline serum in the submucosa enables endoscopic mucosectomy and removal of the polyp in one piece (13). Total excision is important, since it enables the complete histological analysis of the polyp, evaluating the presence or absence of malignancy and, in the case of malignant polyps, assessment of the degree of vascular or lymphatic affectation and proximity to the margin of the resection. With a detailed anatomopathological study, including that of the base of resection, together with complete endoscopic excision, a polypectomy is sufficient treatment, even in the majority of the cases of carcinoma in situ (3, 14). Adenoma Colon free of polyps Polyp in basal colonoscopy: resection High risk according to initial colonoscopy: Multiple adenomas (>2) > 1 cm Villous High-grade dysplasia CRC family history Colonoscopy/ 3 years Hyperplastic polyp or others 2 nd colonoscopy free of polyps Colonoscopy/ 3 years Repeat colonoscopy until colon is free of polyps Do not require follow-up Low risk according to initial colonoscopy: 1 or 2 adenomas < 1cm Tubular or tubularvillous Low-grade dysplasia CRC family history Colonoscopy/ 5 years Fig. 1.- Follow-up of patients with colorectal polyps. Colonoscopy/ 5 years FOLLOW-UP AFTER POLYPECTOMY Depending on the follow-up interval established, 20-50% of the patients that present a colorectal adenoma develop metachronous lesions. This is why these patients should be included in endoscopic surveillance programs once the colon is free of the polyps (Fig. 1). Although the majority of the studies (17, 18) demonstrate that the risk of CRC does not seem to be higher in subjects with a single distal tubular adenoma smaller than 1 cm, depending on the age of the patients, the comorbidity and CRC family history, individualized endoscopic follow-up is recommended (3). The follow-up intervals (19-21) are established according to the characteristics of the polyps removed in the basal colonoscopy and the CRC family history. A colonoscopy is recommendable every 3 years in patients with high risk of developing advanced metachronous adenomas, that is, those with more than two adenomas exceeding 1 cm, villous adenomas with high-grade dysplasia or CRC family history. Endoscopic revision can be delayed up to 5 years in patients with one or two tubular adenomas smaller than 1 cm in the initial colonoscopy and with no CRC family history. In both above-mentioned assumptions, should the colonoscopy reveal that the colon is free of polyps, the following interval for revision shall be extended to 5 years (22). In subjects with multiple adenomas or those with deficient cleaning of the colon, a new colonoscopy may be required immediately after the previous one to guarantee complete resection, or considered one year later (20). The presence of severe dysplasia (level 0) in a totally resected polyp does not modify the above-mentioned follow-up criteria. If a sessile polyp larger than 2 cm is removed, a colonoscopy shall be performed 3-6 months later (23) to determine complete resection. Should polyp residue persist, it should be removed and total resection documented 3-6 months later. If this is not obtained, surgical excision is indicated. ENDOSCOPIC FOLLOW-UP OF CARCINOMA- ADENOMA A malignant polyp is a neoplasia that contains cancerous cells that penetrate the mucosa muscularis to the submucosa (24). The histological criteria of diagnosis and determination of the degree of infiltration correspond to those reported by Haggitt (25) (Fig. 2). The histological finding of a carcinoma in the adenoma removed by colonoscopy is approximately 10%. More than half of these correspond to polyps with non-invasive carcinoma (level 0), whereas polypectomy is an effective therapy, since there is never metastasis.

3 Vol. 95. N. 9, 2003 APPROACH TO A COLORECTAL POLYP 647 Carcinoma in adenoma Carcinoma Haggitt Level "1,2,3" High-grade dysplasia or carcinoma in situ or intramucous carcinoma Haggitt level "0" Residual disease after polypectomy High-risk polyp protocol Residual disease after polypectomy Colonoscopy and biopsy at 3 months Surgical resection** Rectal location Fig. 2.-Haggitt s infiltration levels of carcinoma in adenoma. Cancer invasion of the stalk of a pedunculated polyp is not alone predicative of recurrence, as long as the margins are not affected (26, 27). A series of analysis published on malignant polyps estimated that the residual risk of cancer or ganglia metastasis in pedunculated or sessile polyps endoscopically removed with favorable criteria ranges between 0,3 and 1,5%, respectively (28). Should the invasive carcinoma on resected adenoma present any of the following criteria of residual illness: invasion of the base of the resection or close to it (<2 mm), vascular or lymphatic invasion, poorly differentiated carcinoma, any Haggitt level 4 or incomplete resection, surgical resection of the affected colon segment shall be performed, if necessary, intraoperative colonoscopy or marking of the lesion with China ink (29) to enable localization of the polyp during surgery. The aforementioned should be carried out since the percentage of residual cancer in polyps that fulfil the above-mentioned criteria is 8,5% in pedunculated polyps and up to 14,5% in sessile adenomas (30). In cases of early invasive carcinoma (Haggitt levels 1, 2 and 3) as long as the polyp is pedunculated, complete excision has been accomplished and no characteristics of high-risk of residual illness is present, only endoscopic treatment shall be considered, with follow-up colonoscopy and biopsy of the base of the polyp at 3 months. If this is negative, the standard follow-up polyp protocol shall be followed. Figure 3 summarizes the approach to follow in patients with carcinoma-adenoma. When surgical resection is indicated, the patient s risk of intervention should be evaluated and, if it is high (31), the polyp can be endoscopically resected and the base electrofulgurated every three months. Under this assumption, complete cure of the disease is not guaranteed. If the malignant polyp is located in the lower third portion of the rectum, local excision may be sufficient (32) instead of abdominoperineal resection that has been traditionally practiced. Endorectal ecography (33) provides the Biopsy showing carcinoma High- risk polyp protocol Individualize: Endoanal resection Other surgery Radiotherapy Fig. 3.- Follow-up of patients with carcinoma in adenoma. correct staging of the tumor, since it is able to establish the depth of the invasion of the wall and identify affected ganglia. Furthermore, this technique can determine if local excision is possible, either by endoscopic mucosectomy (23) or surgical resection using a transanal approach. SUPERFICIAL COLORECTAL NEOPLASIAS Superficial colorectal neoplasias (34) are a heterogeneous group of lesions, poorly detected by endoscopic screening, mainly studied in Japan, without information as to the real impact in our environment. The term flat adenoma, introduced by Muto in 1985 (35), is defined as a adenomatous flat polyp less than 1 cm in diameter. It is not easily detected by endoscopic screening, slightly protruded, occasionally with central depression and has greater risk of severe dysplasia (35, 36) than elevated adenomas, although invasion of the submucosa is rare (35). Flat adenoma must be differentiated from depressed lesions (37) that are macroscopically described as lesions less than 1 cm with depression that takes up a large part of the lesion and minimum peripheral elevation. Invasion of the submucosa of these lesions occurs in 32% of the cases (37). Several studies (38,39) suggest that depressed lesions follow a de novo colonic carcinogenesis pathway instead of an adenoma-carcinoma sequence. Another term used among superficial colorectal neoplasia is laterally spreading lesions (37, 40) that are ele-

4 648 R. MUÑOZ GÓMEZ ET AL. REV ESP ENFERM DIG (Madrid) vated flat lesions, with a diameter exceeding 1 cm (main difference with flat adenomas). Two types of lesions are differentiated in this section, granular and non-granular. Several authors (41) support that non-granular lesions could represent different stages in the growth of a flat adenoma. Superficial neoplastic lesions are scarcely expressive in endoscopic screening, however, they are vitally important due to the high-risk of invasion. To identify them by endoscopic screening the cleansing of the colon must be excellent and the practitioner must carry out a thorough examination of the mucosa. The use of chromoscopy with indigocarmine (42) clarifies the nature of the suspected lesion. Also, magnifying endoscopy (43) allows for the definition of the different mucosa patterns and their detailed examination to estimate the invasion of the submucosa and establish the most adequate therapeutic option in each case. The treatment of superficial neoplasias depends on their size and macroscopic aspect. Flat, elevated and small lesions must be endoscopically removed at the moment they are seen with either hot tweezers or mucosectomy. Laterally spreading lesions and depressed lesions can be removed by mucosectomy if no macroscopic signs of submucosa invasion are observed; that is, rough aspect, converging folds, well delimited depression with irregular base and presence of invasive pattern with magnifying colonoscopy (44). Mucosectomy represent a greater risk in lesions exceeding 2 cm for which surgical treatment should be evaluated. SUSPENSION OF FOLLOW-UP Follow-up surveillance of polyps should be interrupted when its risk is greater than its potential benefit and in cases in which it is improbable that endoscopic followup will prolong the patient s survival (45). For this reason, follow-up in patients with an estimated survival of less than 10 years is not recommended. That is, at approximately the age of (9) in absence of co-morbidity. Should polyps with high-risk pathological findings (villous adenoma, exceeding 1 cm, high-grade dysplasia) exist in the previous colonoscopy, another examination after 3 years would be reasonable (46), as long as the expectation of life is greater than 5 years. REFERENCES 1. Bond JH. Polyp Guideline: diagnosis, treatment, and surveillance for patients with colorectal polyps. Am J Gastroenterology 2000; 95: Konishi F, Morson BC. Pathology of colorectal adenomas: a colonoscopic survey. J Clin Pathol 1982; 35: Winawer SJ, Zauber AG, Ho MN, O Brien MJ, Gottlieb LS, Sternberg SS, et al. Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup. N Engl J Med 1993; 329: O Brien MJ, Winawer SJ, Zauber AG, Gottlieb LS, Stenberg SS, Diaz B, et al. The National Polyp Study: Patient and Polyp characteristics associated with high-grade dysplasia in colorectal adenomas. 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