Transanal Ultrasonically Activated Scalpel Technique for Local Excision of Rectal Tumors

Background: Patients with broad based rectal adenomas and selected patients with T1/T2 low and mid-rectal malignant tumors are candidates for a transanal local excision. Difficulty of dissection due to impaired vision caused by continuous or intermittent bleeding has always been a problem in this operation. Method: We describe a simple technique to improve hemostasis and vision using the laparoscopic ultrasonically activated scalpel for excision of rectal tumors. Results: More than 50 patients were treated with this technique over the last 3 years. The authors have used this technique for broad based rectal lesions, up to 12 cm from the anal verge including adenomas spreading over half the rectal circumference without any complications and virtually no bleeding. Conclusion: The principal advantage of the ultrasonically activated scalpel is its excellent coagulation-cutting effect. The use of this instrument for local rectal excisions has proved feasible and avoids the problems of hemostasis and limited access.     

Atypical indications for transanal endoscopic microsurgery to avoid major surgery

Background

Transanal endoscopic microsurgery (TEM) was originally designed for the removal of rectal tumors, principally incipient adenomas, and adenocarcinomas up to 20 cm from the anal verge. However, with the evolution of the technique and the increase in surgeons’ experience, new indications have emerged and TEM may now be used in place of other surgical procedures which are associated with higher morbidity. The aim of our study was to evaluate our group’s use of TEM or transanal endoscopic operations (TEO) for conditions other than rectal tumors.

Methods

An observational study of TEM (using Wolf equipment) or TEO (using Storz equipment) for indications other than excision of rectal tumors was conducted from June 2004 to July 2012.

Results

Four hundred twenty-four procedures were performed using TEM/TEO: removal of adenocarcinomas in 148 (34.9 %) patients, adenomas in 236 (55.7 %), post-polypectomy excision in 12 (2.8 %), removal of neuroendocrine tumors in 8 (1.9 %), and atypical indications in 20 (4.7 %). Atypical indications were pelvic abscess (3), benign rectal stenoses (2), rectourethral fistula after prostatectomy (3), gastrointestinal stromal tumor (3), endorectal condylomata acuminata (1), rectal prolapse (2), extraction of impacted fecaloma in the rectosigmoid junction (1), repair of traumatic and iatrogenic perforation of the rectum (2), and presacral tumor (3).

Conclusions

The use of TEM/TEO in atypical indications may benefit patients by avoiding surgical procedures associated with greater morbidity.     

Transanal endoscopic microsurgery for giant polyps of the rectum

Background

The potential for malignancy in rectal polyps increases with the size of the polyp, and unexpected malignancy is reported in up to 39 % of large rectal adenomas. Transanal endoscopic microsurgery (TEM) offers the possibility of an en bloc full-thickness excision for lesions in the rectum. We present our results with TEM in the removal of giant polyps equal or greater than 4 cm in diameter.

Methods

In the period between 1998 and 2012, TEM was performed in 39 patients with rectal polyps measuring at least 4 cm in diameter. Transrectal ultrasound and/or magnetic resonance imaging of the rectum was used when cancer was suspected.

Results

The polyp was removed with en bloc full-thickness excision in 77 % (n = 30). The preoperative diagnosis was benign rectal adenoma in 89.7 % (n = 35). The median size of the polyps was 30 cm² (range 16–100 cm²). Postoperative complications included bleeding in 4 patients (10.3 %). Histological examination showed unexpected cancer in 4 patients (10.3 %). TEM was curative in 2 of these patients, and the other 2 underwent further surgery. Recurrences occurred in 10 patients (25.6 %) and consisted of 5 adenomas and 5 adenocarcinomas. In 5 patients, these recurrences were treated with endoscopic removal or re-TEM. The remaining 5 underwent total mesorectal excision and/or chemotherapy.

Conclusions

Full-thickness TEM provides a safe and efficient treatment for excision of giant polyps. In case of unexpected cancer, TEM can be curative. Local recurrence can be often treated with a second TEM procedure.     

Local therapy of rectal tumors

PURPOSE: The aim of the study is to outline the rising importance of local treatment of rectal tumors and a changing strategy in therapy of early rectal cancer. METHODS: As the surgical procedure, transanal endoscopic microsurgery was used. Indications for the local procedure were pT1 low-risk tumors and tumors of higher stages in patients with severe risk factors and of those who refused the operation according to oncologic guidelines. RESULTS: A total of 236 rectal adenomas and 98 carcinomas were locally excised using the transanal endoscopic microsurgery technique. Mortality rate was 0.3 percent, and rate of complications requiring surgical reintervention was 5.5 percent in adenomas and 8 percent in carcinomas. Final histology of removed carcinomas revealed 56 pT1, 27 pT2, and 15 pT3 stages. After an average follow-up time of 24 months, two recurrences were observed in the group of patients with pT1 low-risk carcinomas who only underwent local therapy. In both cases, a second intervention for cure was undertaken but for tumors in a late stage. CONCLUSIONS: In selected cases, local therapy of rectal carcinoma avoids high morbidity and mortality of the classical operation. Quality of life will be improved, especially if an artificial anus can be avoided. In case of recurrence, the chance of a secondary procedure for cure is not to be underestimated.     

Treatment of early rectal cancer

The treatment of rectal cancer has undergone a tremendous surgical evolution over the past century. In the past three decades, transanal excision has emerged as a popular treatment option for T1 and selected T2 rectal adenocarcinomas, allowing less morbidity for early cancers. The surgical options offered to the patient are the Parks’ per anal excision and the transanal endoscopic microsurgery (TEM).     

Transanal Endoscopic Microsurgery: A Systematic Review

PURPOSE The aim of this study was to systematically review the evidence relating to the safety and efficacy of transanal endoscopic microsurgery, a relatively new technique used to locally excise rectal tumors, compared with existing techniques such as anterior resections and abdominoperineal resections or local excisions.METHODS We conducted a systematic review of comparative studies and case series of transanal endoscopic microsurgery from 1980 to August 2002.RESULTS Three comparative studies (including one randomized, controlled trial) and 55 case series were included. The first area of study was the safety and efficacy of adenomas. In the randomized, controlled trial, no difference could be detected in the rate of early complications between transanal endoscopic microsurgery (10.3 percent) and direct local excision (17 percent) (relative risk, 0.61; 95 percent confidence interval, 0.29–1.29). Transanal endoscopic microsurgery resulted in less local recurrence (6/98; 6 percent) than direct local excision (20/90; 22 percent) (relative risk, 0.28; 95 percent confidence interval, 0.12–0.66). The 6 percent rate of local recurrence for transanal endoscopic microsurgery in this trial is consistent with the rates found in case series of transanal endoscopic microsurgery (median, 5 percent). The second area of study was the safety and efficacy of carcinomas. In the randomized, controlled trial, no difference could be detected in the rate of complications between transanal endoscopic microsurgery and direct local excision (relative risk for overall early complication rates, 0.56; 95 percent confidence interval, 0.22–1.42). No differences in survival or local recurrence rate between transanal endoscopic microsurgery and anterior resection could be detected in either the randomized, controlled trial (hazard ratio,1.02 for survival) or the nonrandomized, comparative study. There were 2 of 25 (8 percent) transanal endoscopic microsurgery recurrences in the randomized, controlled trial, but no figures were given for recurrence after anterior resection. In the case series, the median local recurrence rate for transanal endoscopic microsurgery was 8.4 percent, ranging from 0 percent to 50 percent. The third comparison was cost of the procedures. Transanal endoscopic microsurgery had both a lower recurrence rate and a lower cost than local excision or anterior resection for adenomas. Although the effectiveness of transanal endoscopic microsurgery could not be established for carcinomas, costs were lower than those for either anterior resection or abdominoperineal resection.CONCLUSIONS The evidence regarding transanal endoscopic microsurgery is very limited, being largely based on a single relatively small randomized, controlled trial. However, transanal endoscopic microsurgery does appear to result in fewer recurrences than those with direct local excision in adenomas and thus may be a useful procedure for several small niches of patient types—e.g., for large benign lesions of the middle to upper third of the rectum, for T1 low-risk rectal cancers, and for palliative, not curative, use in more advanced tumors.© The American Society of Colon and Rectal SurgeonsPublished online: 28 January 2005.     

Local excision of rectal polyp: indications and techniques

The local excision of a rectal polyp is often wrongly considered to be a minor surgical procedure. In reality, the malignant potential of adenomas and the not-infrequent presence of cancer in larger polyps, require, for their removal, an oncologically correct operation with strict indication and accurate execution. Despite an increasing inclination to extend the indications of endoscopic polypectomies to polyps of larger size and villous configuration, the local surgical approach remains the preferred treatment in most cases. Here the indications and the results of different surgical techniques proposed for the local excision of a rectal polyp are reported. Among these procedures, transanal endoscopic microsurgery is gaining a primary role in many circumstances.     

Outcome of Transanal Endoscopic Microsurgery and Adjuvant Radiotherapy in Patients with T2 Rectal Cancer

Purpose The use of transanal endoscopic microsurgery for local excision of rectal cancer has recently gained wide acceptance as a valid and safe alternative for the surgical treatment of T1 tumors. The adequacy of such treatment for T2 tumors, however, is still controversial. This study was designed to evaluate our results with local excision of T2 cancers. Methods Patients with T2 cancer admitted to our hospital between 1995 and 2005 were offered surgery by transanal endoscopic microsurgery if found medically unfit or were unwilling to undergo radical surgery. Patients who were preoperatively staged as T1 tumor but were found to be pathologically T2 also were included. Results Overall, we performed 59 transanal endoscopic microsurgery operations for rectal cancers, of which 21 were for T2 cancers. In 16 (76 percent) of the T2 patients, the tumors were completely removed with clear margins by transanal endoscopic microsurgery and no additional surgery was performed, except for 2 patients who developed radiation-induced complications. Radical surgery was performed in a second operation in five patients because of involved margins and residual disease was found in two. At a median follow-up of three years, all 12 patients who received local excision and radiotherapy remained disease free, whereas a 50 percent recurrence rate was observed in patients who refused adjuvant radiotherapy. Conclusions The results of this study support the feasibility of transanal endoscopic microsurgery for the treatment of selected patients with T2 rectal cancer. The addition of radiotherapy may decrease the rates of early local recurrence. However, at present, this treatment strategy should not be routinely considered for patients who may undergo radical procedures.     

Transanal endoscopic microsurgery for rectal cancer. Long-term oncologic results

Purpose

Local excision of malignant rectal tumors remains controversial due to the lack of prospective studies. The principal aim of this paper is to analyze survival and recurrence of patients with rectal cancer who were operated by transanal endoscopic microsurgery with curative intention.

Methods

In 1997, we started a prospective protocol for patients who had T1/T2 rectal tumors: transanal local full-thickness excision was considered curative in T1 low risk (group A); patients with T1 high-risk and T2 low-risk tumors received postoperative radiotherapy (group B). From 1997 to 2006, 88 patients were enrolled. Sixty eight entered the study after the preoperative workup and 20 patients with an initial diagnosis of adenoma after postoperative definitive pathological assessment.

Results

After definitive histological findings, 54 patients were to group A, 28 to group B, and 6 had immediate radical surgery. One patient was lost for follow-up. At a mean follow-up of 71?months, 7 (4 from group A and 3 from group B) out of 81 patients recurred. Five-year overall survival was of 94% and cancer-specific survival of 96%.

Conclusions

Our data support that transanal endoscopic microsurgery is an adequate treatment for T1 low-risk tumor, and no additional measures are required. For T2 low-risk lesions, our study showed a higher local recurrence rate than that reported after radical surgery but a similar survival outcome.     

Transanal endoscopic microsurgery in rectal adenomas: Experience of six Italian centres

BACKGROUND/AIMS: Transanal endoscopic microsurgery is a minimally invasive technique that allows the excision of benign and selected malignant tumours. We present a study for evaluating surgical morbidity, mortality and local recurrence rate of patients with rectal adenomas treated with transanal endoscopic microsurgery in six different Italian centres following the same protocol. METHODS: A total of 882 patients with rectal lesions (adenomas and early stage of carcinomas) underwent transanal endoscopic microsurgery in six different Surgical Departments from January 1993 to October 2004. Five hundred and ninety patients had preoperative diagnosis of adenomas but 588 patients were regularly followed up to determine treatment efficacy in terms of local recurrence rate. RESULTS: The study involved 588 patients, with a median age of 66 years (25th percentile-75th percentile=58-71 years). No postoperative mortality was reported. Intraoperative complications were observed in three patients (0.5%). Minor complications occurred in 48 patients (8.2%) whereas major complications were found only in 7 patients (1.2%). Definitive histology confirmed adenomas in 530 cases (90.1%). Two patients (0.3%) were lost to follow-up so were not included in the paper. At median follow-up of 44 months (25th percentile-75th percentile=15-74 months), 23 (4.3%) adenomas recurred and were successfully retreated by transanal endoscopic microsurgery [20 cases (87%)] and by conventional surgery [3 patients (13%)]. No further recurrences were observed at subsequent follow-up. Thirty-one (5.3%) patients died during follow-up for old age, cardiac disease, etc. CONCLUSIONS: Transanal endoscopic microsurgery is, in our experience, an effective method for local resection of benign rectal tumours with morbidity of 11.4%, no postoperative mortality and with a percentage of local recurrence of 4.3%.     

Factors associated with complete local excision of small rectal carcinoid tumor

Purpose

Although small rectal carcinoid tumors can be treated using local excision, complete resection can be difficult because tumors are located in the submucosal layer. We evaluate the factors associated with pathologically complete local resection of rectal carcinoid tumors.

Methods

Data were analyzed of 161 patients with 166 rectal carcinoid tumors who underwent local excision with curative intent from January 2001 to December 2010. A pathologically complete resection (P-CR) was defined as an en bloc resection with tumor-free lateral and deep margins. The study classified treatments into three categories for analysis: conventional polypectomy (including strip biopsy, snare polypectomy, and hot biopsy), advanced endoscopic techniques (including endoscopic mucosal resection with cap and endoscopic submucosal dissection), and surgical local excision (including transanal excision and transanal endoscopic microsurgery). We evaluated the P-CR rate according to treatment method, tumor size, initial endoscopic impression and the use of endoscopic ultrasound (EUS) or transrectal ultrasound (TRUS).

Results

The mean tumor size was 5.51?±?2.43 mm (range 2–18 mm) and all lesions were confined to the submucosal layer. The P-CR rates were 30.9, 72.0, and 81.8 % for conventional polypectomy, advanced endoscopic techniques, and surgical local excision, respectively. Univariate analysis showed that P-CR was associated with treatment method, use of EUS or TRUS, and initial endoscopic impression. Multivariate analysis showed that only treatment method was associated with P-CR.

Conclusion

Pathologically complete resection of small rectal carcinoid tumors was more likely to be achieved when using advanced endoscopic techniques or surgical local excision rather than conventional polypectomy.     

经肛门内镜微创手术的适应证与并发症

目的探讨经肛门内镜微创手术(transanal endoscopic microsurgery,TEM)的适应证和并发症。 方法回顾2011年5月至2014年5月在我院接受TEM治疗的135例直肠病变患者的临床资料,分析TEM在直肠病变治疗中的主要适应证和常见并发症。 结果本组135例患者均成功实施TEM,其中行直肠壁全层切除115例,黏膜下及肌层部分切除20例。平均手术时间(66.5±25.0)min(25～120 min),术中平均失血量(10.5±5.5)ml(3～50 ml)。术后病理学检查确诊：直肠腺瘤60例,直肠腺瘤癌变(pTis期)10例,早期直肠癌(pT1期)11例,进展期直肠癌(pT2期)10例,直肠癌经术前放化疗后病理完全缓解(ypT0期)2例,直肠类癌或类癌内镜电切后残灶24例,直肠胃肠道间质瘤5例,直肠平滑肌瘤1例,非肿瘤性息肉10例,直肠子宫内膜异位症2例。所有标本切缘均阴性。术中3例上段直肠前壁肿瘤行全层切除时切入腹腔,即刻行腔内缝合修补成功,未并发腹膜炎或盆腔感染。术后继发肛门出血2例,肺部、泌尿系感染和尿潴留各1例。并发症发生率为5.9%(8/135)。术后平均住院日(2.5±1.2)d(2～8 d)。术后平均随访15.5个月(6～36月),未发现肿瘤复发转移。 结论适合局部切除的直肠局限性肿瘤是TEM的主要适应证。严格选择没有淋巴结转移证据的直肠癌行TEM是安全有效的,已成为直肠局部切除术的首选方式。但目前的循证医学证据仍然有限,仍需要进一步研究论证。     

Transanal Endoscopic Microsurgery is more Effective than Traditional Transanal Excision for Resection of Rectal Masses

Purpose  Transanal endoscopic microsurgery, developed by Buess in the 1980s, has become increasingly popular in recent years. No large studies have compared the effectiveness of transanal endoscopic microsurgery with traditional transanal excision. Methods  Between 1990 and 2005, 171 patients underwent traditional transanal excision (n = 89) or transanal endoscopic microsurgery (n = 82) for rectal neoplasms. Medical records were reviewed to determine type of surgery, resection margins, specimen fragmentation, complications, recurrence, lesion type, stage, and size. Results  The groups were similar with respect to age, sex, lesion type, stage, and size. Mean follow-up was 37 months. There was no difference in the complication rate between the groups (transanal endoscopic microsurgery 15 percent vs. traditional transanal excision 17 percent, P = 0.69). Transanal endoscopic microsurgery was more likely to yield clear margins (90 vs. 71 percent, P = 0.001) and a nonfragmented specimen (94 vs. 65 percent, P < 0.001) compared with transanal excision. Recurrence was less frequent after transanal endoscopic microsurgery than after traditional transanal excision (5 vs. 27 percent, P = 0.004). Conclusions  Transanal endoscopic microsurgery is the technique of choice for local excision of rectal neoplasms. Dr. Cataldo is an instructor and an invited speaker for Richard Wolf Medical Instruments Company. Read at the meeting of The American Society of Colon and Rectal Surgeons, St. Louis, Missouri, June 2 to 6, 2007.     

Incidence,treatment and outcome of rectal stenosis following transanal endoscopic microsurgery

Background  

As an alternative to more radical abdominal surgery, transanal endoscopic microsurgery (TEM) offers a minimally invasive solution for the excision of certain rectal polyps and early-stage rectal tumours. The patient benefits of TEM as compared to radical abdominal surgery are clear; nevertheless, some drawback is possible. The aim of our study was to determine the risk factors, treatment and outcomes of rectal stenosis following TEM.     

Transanal endoscopic microsurgery

PURPOSE: The aim of this study was to describe a single institution's experience with transanal endoscopic microsurgery in patients with benign and malignant rectal tumors. PATIENTS: Between January 1992 and April 1998, 75 patients with a mean follow up of 38 months, underwent transanal endoscopic microsurgery excision of benign (46) or malignant (29) rectal tumors, located 3 to 18 cm from the dentate line. RESULTS: A total of 3 of 46 (6.5 percent) patients with benign tumors underwent conversion to radical surgery owing to tumor size. During the follow-up period, benign tumor recurrence was observed in four (9 percent) patients, three of whom were managed by repeat transanal endoscopic microsurgery, whereas one required radical surgery. Histologic staging of malignant tumors was T1 (10), T2 (10), and T3 (9). Seven patients with either inadequate resection margins or T3 tumors were complimented with radical surgery. Of the remaining 22 patients, 11 received adjuvant radiation therapy whereas 11 had no further treatment. Four (18 percent) had recurrent disease, which was managed by repeat transanal endoscopic microsurgery in two, radical surgery in one, and laser ablation in one. No cancer-related deaths were observed during the follow-up period. There was one operative mortality in a cardiac-crippled patient. Postoperative complications were mainly of a minor character and included fever, urinary retention, and bleeding; none of which required reintervention. Rectourethral fistula developed in one patient who underwent repeat transanal endoscopic microsurgery excision for a T3 malignancy. Fecal soiling was transient in three patients and persisted in two. CONCLUSION: Transanal endoscopic microsurgery excision is a safe and precise technique that is well tolerated even in high operative risk patients. Transanal endoscopic microsurgery may become a procedure of choice for benign rectal tumors and selected early malignant neoplasms.     

Transanal endoscopic microsurgical submucosa dissection in the treatment of rectal adenomas and T1 rectal cancer

Background

The treatment of flat rectal adenomas is challenging. The technical difficulty and the potential of malignancy in suspected benign lesions are the factors in question. Surgical and interventional endoscopic techniques are implemented in Europe without a clear strategy. To minimize recurrent adenoma and unclear histopathological work up en bloc excision is desirable.

Methods and results

We demonstrate in this article the transanal endoscopic microsurgical submucosa dissection (TEM-ESD) procedure as a feasible method for en bloc excision of rectal adenomas and early rectal cancer. The surgical technique is demonstrated in detail with the help of a video of the operation that is available online. The results of a consecutive series of 78 patients are presented.

Conclusion

TEM-ESD is a safe procedure for resection of rectal adenomas and low risk carcinomas. It offers the possibility of organ preservation and minimizes functional disturbances. In case of a necessary salvage operation, the preserved integrity of the rectal muscle tube grants maximal oncological safety.

     

A systematic review of transanal minimally invasive surgery (TAMIS) from 2010 to 2013

Transanal minimally invasive surgery (TAMIS) was introduced as an alternative to transanal endoscopic microsurgery in 2010. Over the past 4 years, considerable international experience has been gained with this approach. Most published reports focus on TAMIS for local excision of rectal neoplasia, but there are other important applications such as transanal mesorectal excision for rectal cancer. This comprehensive review details the progress with TAMIS since its inception. Robotic transanal surgery is a natural evolution of TAMIS still in its early infancy, which is also reviewed. A comprehensive search of PubMed, EMBASE, the Cochrane Library, and Web of Knowledge was performed. Since the inception of TAMIS in 2009, 33 retrospective studies and case reports, and 3 abstracts have been published on TAMIS for local excision of rectal neoplasms, which represents a combined n = 390 TAMIS procedures performed worldwide using eight different types of TAMIS platforms. A total of 152 lesions were excised for benign disease including adenomas and high-grade dysplasias (39 %), 209 for malignancy for carcinomas in situ and adenocarcinomas (53.5 %). Twenty-nine (7.5 %) of TAMIS resections were for other pathology, of which the majority (23/29) were neuroendocrine lesions. The remaining resections were for mucocele, gastrointestinal stromal tumor, melanoma, and fibrosis. Robotic-TAMIS has also been reported, however, data are extremely limited as there are only 7 case reports (combined n = 11) in the published literature. Success with Robotic-TAMIS has been demonstrated with various patient positions and by use of a special glove port. Transanal total mesorectal excision using the TAMIS platform has also been demonstrated is several small series, and the feasibility of performing pure transanal total mesorectal excision has also been reported. Combined, n = 78 cases of transanal total mesorectal excision have been performed using TAMIS. The advantages of TAMIS-assisted transanal total mesorectal excision are discussed.     

A comparison of transanal excision and endoscopic resection for early rectal cancer

AIM: To compare the outcomes of endoscopic resection with transanal excision in patients with early rectal cancer.METHODS: Thirty-two patients with early rectal cancer were treated by transanal excision or endoscopic resection between May 1999 and December 2007. The patients were regularly re-examined by means of colonoscopy and abdominal computed tomography after resection of the early rectal cancer. Complications, length of hospital-stay, disease recurrence and follow up outcomes were assessed.RESULTS: Sixteen patients were treated by endoscopic resection and 16 patients were treated by transanal excision. No significant differences were present in the baseline characteristics. The rate of complete resection in the endoscopic resection group was 93.8%, compared to 87.5% in the transanal excision group (P = 0.544). The mean length of hospital-stay in the endoscopic resection group was 2.7 ± 1.1 d, compared to 8.9 ± 2.7 d in the transanal excision group (P = 0.001). The median follow up was 15.0 mo (range 6-99). During the follow up period, there was no case of recurrent disease in either group.CONCLUSION: Endoscopic resection was a safe and effective method for the treatment of early rectal cancers and its outcomes were comparable to those of transanal excision procedures.     

Long-term results of transanal endoscopic microsurgery after endoscopic polypectomy of malignant rectal adenoma

Background

There is no consensus on the treatment and prognosis of malignant rectal polyps. The aim of the present study was to determine the role of transanal endoscopic microsurgery (TEM) after endoscopic complete polypectomy of malignant rectal adenomas with long-term follow-up.

Methods

Of 105 patients with pT1 rectal carcinoma in 32 patients TEM followed complete endoscopic polypectomy while 73 had primary TEM. Local recurrence (LR), distant metastasis, overall and cancer-specific survival were determined by the Kaplan–Meier method.

Results

Median follow-up was 9.1 years. In 32 patients with TEM following complete polypectomy no residual cancer was found. LR occurred in 3/28 (11%) patients with low-risk carcinoma (pT1 G1/2/X, L0/X, R0) and in 1/4 (25%) with high-risk carcinoma (pT1 G3/4 or L1). After primary TEM with complete resection (minimal distance >1 mm) LR occurred in 6/60 (10%) with low-risk carcinoma. After incomplete TEM resection (minimal distance ≤1 mm) LR occurred in 3/8 (38%) patients with low-risk and in 1/5 (20%) patients with high-risk carcinoma. Grading was the only significant risk factor for LR after endoscopic polypectomy followed by TEM (p = 0.002). At all outcomes did not differ between postpolypectomy TEM and primary TEM.

Conclusions

Patients with malignant rectal polyps removed by endoscopic polypectomy have a substantial risk of LR even if TEM of polyp site is cancer free. Risk of LR depends on tumor characteristics. In low-risk carcinoma long-term follow-up is necessary. The high LR rate in patients with high-risk rectal carcinoma restricts the use of TEM alone.

     

Colorectal carcinogenesis

PURPOSE: In view of the changing concept of colorectal carcinogenesis during the last 20 years, a historical review of colorectal carcinogenesis is presented. METHODS: The changing concept of colorectal carcinogenesis was presented in four different periods: 1) carcinogenesis based on surgical materials; 2) carcinogenesis based on polypectomy materials; 3) carcinogenesis based on nonpolypoid neoplasms; 4) carcinogenesis based on molecular biology. RESULTS: In the first period, large adenomas were thought to play the most important role as precursors to colorectal carcinomas; however, in the second period, smaller and nonpedunculated adenomas were found to have a much higher malignancy potential than previously thought. The discovery of nonpolypoid neoplasms, including flat and depressed adenomas/carcinomas, shed light on the new precursor of colorectal carcinomas that were not recognized in the past. Molecular biology clarified a lack of K -ras mutation in nonpolypoid, particularly depressed, neoplasms, suggesting the presence of a novel pathway of colorectal carcinogenesis, different from that in polypoid neoplasms. CONCLUSIONS: The concept referred to as the “adenoma-carcinoma sequence” changed because colonoscopic polypectomy specimens were studied, and rather small, nonpedunculated adenomas were found to play an important role as precursors of colorectal carcinomas. The discovery of nonpolypoid neoplasms provides us with new precursors of colorectal carcinomas. The genetic alterations in nonpolypoid neoplasms seem to differ from those in polypoid neoplasms, and genetic alterations in so-called de novo carcinomas need to be clarified