DOI: 10.5124/jkma.2010.53.7.549 pissn: 1975-8456 eissn: 2093-5951 http://jkma.org Focused Issue of This Month Endoscopic Diagnosis and Treatment of Colorectal Cancers Dong Kyung Chang, MD Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea Corresponding author: Dong Kyung Chang E-mail: dkchang@skku.edu Received May 30, 2010 Accepted June 13, 2010 Abstract Colonoscopy is the best screening tool to detect colorectal cancer in early stage and also a potent arm to prevent development of cancer by removing colorectal adenoma. Superficial colorectal neoplastic lesions are primary targets of colonoscopic resection. Adenoma, carcinoma in situ, and cancer with minimal submucosal invasion are included in this category. One stage endoscopic treatment without the preceding biopsy confirmation is preferable, and thus endoscopic evaluation to identify the characteristics of the superficial neoplastic lesions is of importance. Gross endoscopic appearance and pit pattern and/or vascular pattern of the surface epithelium of the polypoid and nonpolypoid superficial lesions provide useful clue to predict histology of the lesions and depth of cancer invasion with reasonable accuracy. Appropriate treatment can be directed through this endoscopic evaluation step. Conventional snare polypectomy and endoscopic mucosal resection is mainstay of endoscopic treatment. Recently introduced endoscopic submucosal dissection facilitated en bloc resection of a large neoplastic lesion. After endoscopic resection, accurate pathologic evaluation is necessary to determine whether colonoscopic follow up or further surgical resection is needed. Poorly or undifferentiated cancers, cancers massively invading submucosal layer deeper than 1,000 micrometer, lymphovascular invasion of cancer cells, or presence of cancer cells on the resection margin are indications of further surgical resection because of the significant risk in metastasis to the regional lymph nodes. Colorectal polyps and early cancers are effectively treated by colonoscopy in most cases. Early detection by an adequate screening program is essential for this purpose. Keywords: Colorectal polyp; Colorectal cancer; Colonoscopy; Polypectomy; Endoscopic submucosal dissection c Korean Medical Association This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 549
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Endoscopic Diagnosis and Treatment of Colorectal Cancers Table 1. Guidelines for screening colonoscopy for the early detection of colorectal cancer and adenomas for average-risk women and men aged 50 years and older [1] Test Interval Key Issues for Informed Decisions Insertion to 40 cm or to splenic flexure is required Complete or partial bowel prep is required Sedation usually is not used, so there may be some discomfort during the procedure Sigmoidoscopy Every 5 years The protective effect of sigmoidoscopy is primarily limited to the portion of the colon examined Patients should understand that positive findings on sigmoidoscopy usually result in a referral for colonoscopy Complete bowel prep is required Conscious sedation is used in most centers; patients will miss a day of work and will Colonoscopy Every 10 years need a chaperone for transportation from the facility Risks include perforation and bleeding, which are rare but potentially serious; most of the risk is associated with polypectomy Table 2. Guidelines for surveillance after polypectomy by ACS, USMTFCC, ACR [1] Risk category Interval Recommendation Comment Patients with small for average-risk An exception is patients with a hyperplastic polyposis syndrome. rectal hyperplastic - individuals They are at increased risk for adenomas and colorectal cancer polyps and need to be identified for more intensive follow-up. Patients with 1 or 2 5 to 10 years Colonoscopy The precise timing within this interval should be based on other tubular adenomas after the initial clinical factors (such as prior colonoscopy findings, family history, with low-grade polypectomy and the preferences of the patient and judgment of the physician). dysplasia Patients with 3 to 3 years after Colonoscopy Adenomas must have been completely removed. If the follow up 10 adenomas, the initial colonoscopy is normal or shows only 1 or 2 small tubular or 1 adenoma >1 cm, polypectomy adenomas with low-grade dysplasia, then the interval for the or any adenoma with subsequent examination should be 5 years. villous features or high-grade dysplasia Patients with >10 <3 years Colonoscopy Consider the possibility of an underlying familial syndrome. adenomas on a after the initial single examination polypectomy Patients with sessile 2 to 6 months Colonoscopy Once complete removal has been established, subsequent adenomas that are to verify com- surveillance needs to be individualized based on the endoscopists removed piecemeal plete removal judgment. Completeness of removal should be based on both endoscopic and pathologic assessments. 551
Chang DK Table 3. Morphologic classification of type 0 lesions with superficial appearance at colonoscopy (Paris-Japanese classification) [11] Polypoid type* Nonpolypoid type Mixed types Pedunculated (0-Ip) Slightly elevated (0-IIa) Elevated and depressed (0-IIa+IIc) Sessile (0-Is) Completely flat (0-IIb) Depressed and elevated (0-IIc+IIa) Mixed (0-Isp) Slightly depressed (0-IIc) Sessile and depressed (0-Is+IIc) *Polypoid lesions are elevated more than 2.5 mm above the surrounding mucosa. Nonpolypoid lesions are flat, elevated less than 2.5 mm, or are depressed less than 2.5 mm. Slightly elevated lesions should not be mistaken for sessile or flat lesions. Table 4. Subtypes of LST lesions: morphologic classification of LST lesions and their correspondence in the Paris-Japanese classification [11] Subtypes of LST Classification in type 0 LST granular LST nongranular Homogenous type 0-IIa Nodular mixed type 0-IIa, 0-Is IIa, 0-IIa Is Elevated type 0-IIa Pseudodepressed type 0-IIa IIc, 0-IIc IIa LST- G (granular) Kudo:LST-G-H (homogeneous) LST-G-M(nodular Mixed) Paris:IIa IIa+Is LST-NG (non-granular) Kudo:LST-NG-F(flat elevated) LST-NG-PD (pseudodepressed) Paris:IIa IIc+IIa 552
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Chang DK Table 5. Categories of the pit pattern at the surface of the colonic mucosa [11] Histology Pit patterny Treatment selection Nonneoplastic Normal mucosa (normal round crypts, regular) I HP lesion (enlarged stellar crypts, regular) II No treatment adenomatous Neoplastic lesion (elongated, sinuous crests) IIIL Neoplastic Neoplastic lesion (narrowed round pits, irregular) IIIS Endoscopic resection Neoplastic lesion (branched or gyrus-like crests) IV Neoplastic cancer Malignant lesion (irregular surface) Vi Endoscopic resection Malignant lesion (amorphous surface) VN Surgery Table 6. Categories of the vasucular pattern at the surface of the colonic mucosa evaluated by narrow band imaging [11] Histology Vascular pattern Treatment selection Non-neoplastic Normal well-defined capillaries surrounding pits opening No treatment Faint poor visibility of capillaries around enlarged pits No treatment Neoplastic Network essels organized in a large and regular mesh Endoscopic resection (adenoma) Dense enlarged vessels of regular size at top of elongated epithelial crests Endoscopic resection Cancer Irregular enlarged vessels of irregular diameter and diverging directions Sparse poor distribution of irregular vessels with diverging directions Endoscopic resection Surgery Table 7. Endoscopic treatment methods of colon polyps or early colorectal cancers Conventional snare polypectomy Endoscopic mucosal resection (EMR) EMR with pre-cutting (EMR-P), EMR with a cap (EMR-C), EMR with ligation (EMR-L) Piecemeal endoscopic mucosal resection (EPMR) Endoscopic submucosal dissection (ESD) 554
Endoscopic Diagnosis and Treatment of Colorectal Cancers Figure 1. Conventional snare polypectomy. 555
Chang DK Figure 2. Endoscopic mucosal resection. 556
Endoscopic Diagnosis and Treatment of Colorectal Cancers Figure 3. Endoscopic mucosal resection with precutting. 557
Chang DK Figure 4. Piecemeal endoscopic mucosal resection. 558
Endoscopic Diagnosis and Treatment of Colorectal Cancers Table 8. Indications for ESD [22] 1. Large (> 20 mm in diameter) lesions for which endoscopic treatment is indicated but for which en bloc resection by snare EMR would be difficult LST-NG, particularly those of the pseudodepressed type Lesions with a type VI pit pattern Carcinoma with submucosal infiltration Large elevated lesion suspected to be cancer 2. Mucosal lesions with fibrosis caused by prolapse due to biopsy or peristasis of the lesion 3. Sporadic localized tumors in chronic inflammation such as in ulcerative colitis 4. Local residual early cancer after endoscopic resection Supplements) 1. To determine whether ESD is indicated, magnification, in addition to standard colonoscopic observation, is essential 2. In principle, a lesion with massive submucosal invasion is not indicative 3. LST-G should be treated on the basis of findings of both magnification and standard colonoscopy as follows: homogenous granular type: EPMR focal mixed nodular type: planned EPMR or ESD large, whole nodular type: ESD or surgery A large LST-G with type V pit pattern should not be cut. The skill level of the colonoscopist should also be considered in the selection of the therapeutic method (EPMR, ESD, or surgery) 559
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