Predisposing causes of intestinal cancer

Diet quality and colorectal tumor risk in persons with Lynch syndrome

BACKGROUND

Persons with Lynch syndrome (LS) have an increased risk of developing colorectal tumors (CRTs). Adherence to diet quality indices associated with colorectal cancer (CRC) risk in the general population has not been studied before in LS.

METHODS

Dietary habits of 490 participants with LS from a prospective cohort study was collected using a food frequency questionnaire. The Dutch Healthy Diet index 2015 (DHD15-index) and Dietary Approaches to Stop Hypertension (DASH) were used to score food-based diet quality. Diet quality scores were divided into tertiles where a higher tertile reflects a higher diet quality. Multivariable Cox proportional hazard regression models were used to estimate the association between the DHD15-index, DASH score and CRT risk.

RESULTS

During a median follow-up time of 53.4 months, 210 participants (42.9%) developed CRTs. The DHD-index and DASH score were not associated with CRT risk; hazard ratios for highest vs. lowest tertile were 1.00 (95% Confidence Interval (CI): 0.67-1.48) and 1.11 (95% CI: 0.74-1.69), respectively. No linear trends across the DHD-index and DASH score tertiles were observed (P-trend = 0.97 and 0.83 respectively).

CONCLUSION

In contrast to observations in the general population, no evidence for an association between the food-based DHD15-index or DASH score and CRT risk was observed in persons with LS. Further studies are needed investigating the association between diet quality and mechanisms leading to the development of LS-associated tumors.

Impact of tumor location on lymph node metastasis in T1 colorectal cancer

PURPOSE

Data evaluating the risk of lymph node metastasis depending upon the location of the primary tumor are limited in patients with T1 colorectal cancer. We aimed to evaluate the impact of tumor location on lymph node metastasis in T1 colorectal cancer.

METHODS

Patients who underwent an oncologic resection with curative intent for T1 adenocarcinoma of the colon and rectum between January 1997 and October 2014 were assessed. Exclusion criteria were distant organ metastases, previous or concurrent cancer, past history of surgical or medical cancer treatment, preoperative chemoradiation, and patients with inflammatory bowel disease or polyposis syndromes.

RESULTS

Out of 232 (56 % male) patients fulfilling the study criteria, 24 (10 %) had lymph node metastasis. Age (65 vs 61 years, p = 0.1), gender (55 vs 63 % male, p = 0.5), tumor size (2 vs 2 cm, p = 0.49), and lymphovascular invasion (5 vs 8 %, p = 0.46) were not associated with lymph node metastasis. While there was no statistical significance (p = 0.2), lymph node positivity was higher in rectal cancer (14 %, n = 11/79) compared to colon cancer (9 %, n = 13/153).

CONCLUSIONS

Although it was not statistically significant, lymph node positivity varies based on tumor location of T1 colorectal adenocarcinoma regardless of fundamental tumor characteristics including size, differentiation, and lymphovascular invasion.

Biologic and molecular markers for staging colon carcinoma

Biomarkers in the field of pathology and oncology may allow for the detection of disease, assessment of prognosis or to predict response to certain therapy. Molecular abnormalities in colorectal cancer genesis may occur due to chromosome instability, microsatellite instability and DNA methylation (CpG island methylator phenotype). These alterations are associated in some cases to sporadic carcinomas whereas in others are seen in syndrome-related tumors and are the basis for the use of different biomarkers in the clinical setting. These may include mismatched repair gene/proteins, RAS, BRAF, PIK3CA, which help to determine tumor prognosis and predict response to certain drugs.

Rectal cancer: An evidence-based update for primary care providers

Rectal adenocarcinoma is an important cause of cancer-related deaths worldwide, and key anatomic differences between the rectum and the colon have significant implications for management of rectal cancer. Many advances have been made in the diagnosis and management of rectal cancer. These include clinical staging with imaging studies such as endorectal ultrasound and pelvic magnetic resonance imaging, operative approaches such as transanal endoscopic microsurgery and laparoscopic and robotic assisted proctectomy, as well as refined neoadjuvant and adjuvant therapies. For stage II and III rectal cancers, combined chemoradiotherapy offers the lowest rates of local and distant relapse, and is delivered neoadjuvantly to improve tolerability and optimize surgical outcomes, particularly when sphincter-sparing surgery is an endpoint. The goal in rectal cancer treatment is to optimize disease-free and overall survival while minimizing the risk of local recurrence and toxicity from both radiation and systemic therapy. Optimal patient outcomes depend on multidisciplinary involvement for tailored therapy. The successful management of rectal cancer requires a multidisciplinary approach, with the involvement of enterostomal nurses, gastroenterologists, medical and radiation oncologists, radiologists, pathologists and surgeons. The identification of patients who are candidates for combined modality treatment is particularly useful to optimize outcomes. This article provides an overview of the diagnosis, staging and multimodal therapy of patients with rectal cancer for primary care providers.

When is local excision appropriate for "early" rectal cancer?

Local excision is increasingly performed for “early stage” rectal cancer in the US; however, local recurrence after local excision has become a controversial issue in Western countries. Local recurrence is considered to originate based on the type of tumor and procedure performed, and in surgical margin-positive cases. This review focuses on the inclusion criteria of “early” rectal cancers for local excision from the Western and Japanese points of view. “Early” rectal cancer is defined as T1 cancer in the rectum. Only the tumor grade and depth of invasion are the “high risk” factors which can be evaluated before treatment. T1 cancers with sm1 or submucosal invasion <1,000 μm are considered to be “low risk” tumors with less than 3.2 % nodal involvement, and are considered to be candidates for local excision as the sole curative surgery. Tumors with a poor tumor grade should be excluded from local excision. Digital examination, endoscopy or proctoscopy with biopsy, a barium enema study and endorectal ultrasonography are useful for identifying “low risk” or excluding “high risk” factors preoperatively for a comprehensive diagnosis. The selection of an initial local treatment modality is also considered to be important according to the analysis of the nodal involvement rate after initial local treatment and after radical surgery.

Microcirurgia endoscópica transanal e tratamento adjuvante no câncer retal precoce

RACIONAL: A excisão total do mesorreto é considerada a operação padrão no tratamento dos tumores do reto, apesar de não existir comprovação científica de que ela deva ser usada para todos os estádios da doença. Tem sido demonstrado que em casos escolhidos de tumores retais, resultados promissores podem ser conseguidos com tratamento local por microcirurgia endoscópica transanal. Tais tumores, denominados de câncer retal precoce, são tumores T1 - menores do que 4 cm -, bem diferenciados sem invasão angiolinfática pT1 Sm1. Como o risco de comprometimento linfonodal nesses tumores é de aproximadamente 3%, a ressecção local teria grande chance de ser curativa. OBJETIVO: Apresentar os resultados de uma série prospectiva não randômica de pacientes portadores de câncer retal precoce submetidos ao tratamento local por microcirurgia endoscópica transanal. MÉTODOS: Entre 2002 e 2010, 38 pacientes avaliados por protocolo pré-operatório como portadores câncer retal precoce foram submetidos à ressecção local endoscópica microcirúrgica de toda a parede retal com o tumor quando localizado entre 2 e 8 cm da linha pectínea. A avaliação pré-operatória consistiu de toque retal, retossigmoidoscopia rígida para macrobiópsias, enema opaco e/ou colonoscopia, ultrassonografia endoretal e abdominal, tomografia axial computadorizada do abdome, radiografia do tórax e dosagem sérica do CEA. Realizou-se seguimento pós-operatório endoscópico e ultrassonográfico endoretal a cada três meses nos dois primeiros anos, e a cada seis nos próximos três anos, além de dosagem do CEA a cada seis meses nesse mesmo período de cinco anos. Avaliou-se a recidiva tumoral, morbidade e mortalidade. RESULTADOS: Após avaliação anatomopatológica da lesão, 29 cânceres retais precoces foram categorizados como de baixo risco e nove sendo de alto. O seguimento na série variou de um a sete anos. Recidiva tumoral foi confirmada em dois casos dos 38 (5,26%), uma lesão considerada de alto e a outra de baixo risco. CONCLUSÃO: Microcirurgia endoscópica transanal, associada ou não à quimioradioterapia, pode ser considerada atualmente o padrão-ouro na ressecção retal local, apresentando resultados animadores em casos escolhidos de tumores retais precoces de baixo risco.

Small, Depressed-Type Early Colon Cancer Invading Shallow Submucosal Layer With Extensive Lymph Node Metastasis: A Case Report

Early colorectal cancers are defined as invasive tumors that are limited to the mucosal layer or submucosal layer (SM), regardless of the presence or absence of lymph node (LN) metastasis. The reported incidence of LN metastasis of SM1 colon cancers is 0 - 5.9%, but the incidence in SM2 and SM3 colon cancers could be as high as 11.3 - 25.0%, and risk factors for LN metastasis include depth of SM invasion, growth patterns (polypoid or non-polypoid), histological sub-classification (moderate or poor differentiation) and regional lymphatic and vascular invasion. Among colorectal cancers with non-polypoid growth, the malignant potential is higher for depressed, than polypoid types, even for small tumors. Herein, we describe a patient with small, depressed-type early colon cancer with extensive LN metastasis and superficial SM invasion (pSM 450 µm). Six courses of chemotherapy with mFOLFOX6 and bevacizumab reduced the size of the LN metastases, thus eliciting a partial response (PR) according to the response evaluation criteria in solid tumors (RECIST).

Management of early rectal cancer

BACKGROUND

Early rectal cancer (ERC) is adenocarcinoma that has invaded into, but not extended beyond, the submucosa of the rectum (that is a T1 tumour). Local excision is curative for low-risk ERCs but for high-risk cancers such management is controversial.

METHODS

This review is based on published literature obtained by searching the PubMed and Cochrane databases, and the bibliographies of extracted articles.

RESULTS AND CONCLUSION

ERC presents as a focus of malignancy within an adenoma, as a polyp, or as a small ulcerating adenocarcinoma. Preoperative staging relies on endorectal ultrasonography and magnetic resonance imaging. Pathological staging uses the Haggitt and Kikuchi classifications for adenocarcinoma in pedunculated and sessile polyps respectively. Lymph node metastases increase with the Kikuchi level, with a 1-3 per cent risk for submucosal layer (Sm) 1, 8 per cent for Sm2 and 23 per cent for Sm3 lesions. Low-risk ERCs may be treated endoscopically or by a transanal procedure. Transanal excision or transanal endoscopic microsurgery may be inadequate for high-risk ERCs and adjuvant chemoradiotherapy may be appropriate. There is a low rate of recurrence after local surgery for low-risk ERCs but this increases to up to 29 per cent for high-risk cancers.

Depressed-type of early colon cancer with extensive lymph node metastasis

Early colorectal cancer (ECC) is defined as invasive tumor limited to the colonic and rectal mucosa or submucosa, regardless of the presence or absence of lymph node metastasis. The incidence of lymph node metastasis in ECC ranges from 0 to 15.4%, and risk factors include depth of submucosal invasion, growth patterns (polypoid or non-polypoid), histologic subclassification, and lymphatic invasion. Of non-polypoid growth patterns, the depressed types of colorectal cancer have higher malignant potential than polypoid types, even for small sizes. Unfortunately, this type is also difficult to detect on colonoscopic examination. In this report, we describe a case of depressed type ECC with extensive lymph node metastasis without regional lymph node involvement.

Local excision of stratified T1 rectal cancer

BACKGROUND

Local excision has been accepted therapy for T1 rectal cancers. A recent study demonstrated that primary tumors with deeper submucosal invasion were associated with a higher rate of lymph node metastases than those with shallow invasion. Our aim was to determine the effect of the depth of submucosal penetration on recurrence and mortality rates following transrectal excision of T1 tumors.

METHODS

This was a 34-year retrospective review of patients who had transrectal excision with clear margins for T1 rectal cancer. Tumors were stratified into submucosal (SM) levels, and recurrence and mortality rates were determined.

RESULTS

Of 101 patients with T1 rectal cancer undergoing local excision, 31 had a full-thickness transrectal excision. Eight (26%) of the 31 patients developed a local recurrence, 2 of whom had both a local and distant recurrence. Four patients (13%) died from metastatic rectal cancer.

CONCLUSIONS

The recurrence rate for transrectal excision of T1 rectal cancer is high. It may be beneficial for patients with early rectal cancer to have postoperative chemoradiation therapy or a more radical surgical procedure.

Small, flat colorectal neoplasias in long-standing ulcerative colitis detected by high-resolution electronic video endoscopy

BACKGROUND

High-resolution video endoscopy complemented with chromoscopy allows for more detailed visualization of the colonic mucosal surface.

METHODS

Using high-resolution video endoscopy and chromoscopy, we investigated 85 patients with extensive ulcerative colitis with a disease duration of at least 10 years who were taking part in a cancer surveillance program.

RESULTS

In 38 of the 85 patients, 104 polyps were detected at endoscopy. Seventy-seven (74%) of the 104 polyps were endoscopically flat, 21 (20%) were sessile, 3 (3%) were pedunculated, and 3 (3%) had no recorded morphology. Twenty-three (22%) polyps were neoplastic (15 flat, 5 sessile, 2 pedunculated, 1 not recorded). Low-grade dysplasia was found in 21 of the 23 neoplastic polyps and high-grade dysplasia in the remaining 2 (1 flat tubular adenoma and 1 sessile villous adenoma with invasive growth). Flat polyps were small, with a diameter of 5 mm or less in 73% (n = 56) of cases. At histology flat polyps revealed either flat adenomas (n = 11; 14.3%), tubular or villous structures with dysplastic cells at the lower part of the crypts (n = 4; 5.2%), flat hyperplastic polyps (n = 26; 34%), inflammatory mucosa (n = 5; 6.5%), or mucosa in remission (n = 31; 40%).

CONCLUSION

The use of high-resolution video endoscopy complemented with chromoscopy in ulcerative colitis enables the detection of flat neoplastic polyps. The existence of those hitherto undetected neoplasms in ulcerative colitis and their possible role in the histogenesis of colorectal cancer in ulcerative colitis deserve further investigation.

The Funen Adenoma Follow-up Study. Incidence and death from colorectal carcinoma in an adenoma surveillance program

The results of a prospective randomized study of 1056 patients with colorectal adenomas are presented. After initial polypectomy from 1978 to 1992, patients were allocated at random to different follow-up intervals varying from 6 to 48 months, except 53 patients who were allocated to intervals of 6 months. The examinations were mainly done by colonoscopy. Ten patients developed colorectal carcinoma, a number similar to that expected (7.96), when compared with a sex- and age-matched normal Danish population. The expected number of carcinomas was also calculated from adenoma to carcinoma conversion rates estimated in other studies and compared with that observed. If all carcinomas develop in large (> or = 10 mm) adenomas or adenomas with severe dysplasia, the expected number of carcinomas would have been 62 and 110, respectively, indicating a significant reduction of carcinomas in the present study. One patient died of colorectal carcinoma, which is significantly lower than the number expected (7.58). Two patients died of complications from therapeutic and diagnostic colonoscopy--that is, 2 deaths in 3959 colonoscopies. In conclusion, the follow-up strategy has resulted in a mortality from colorectal carcinoma which is reduced when compared with the normal population, in spite of an apparently similar incidence of carcinoma. However, previous suggested adenoma-carcinoma conversion rates indicate that a major reduction of incidence actually has taken place.

Antioxidant vitamins or lactulose for the prevention of the recurrence of colorectal adenomas. Colorectal Cancer Study Group of the University of Modena and the Health Care District 16

Colonic adenomas represent the natural precursor lesions of most colorectal cancers. The treatment of choice is endoscopic polypectomy. However, after endoscopic removal, polyps recur in a large fraction of cases. Thus, we evaluated the effect of antioxidant vitamins or lactulose on the recurrence rate of adenomatous polyps. After polypectomy, 255 individuals were randomized into three groups. Group 1 was given vitamin A (30,000 IU/day), vitamin C (1 g/day), and vitamin E (70 mg/day); Group 2 was given lactulose (20 g/day); Group 3 received no treatment. Forty-six subjects had to be excluded because the histologic diagnosis was not consistent with adenoma. The remaining 209 individuals were included in the analysis according to the "intention to treat" criterion, though 34 did not adhere to the scheduled treatment or were lost during the follow-up. Subjects were followed at regular intervals for an average of 18 months. Polyps recurring before one year from index colonoscopy were considered missed by the endoscopist. In the 209 evaluable subjects, the percentages of recurrence of adenomas were 5.7 percent, 14.7 percent, and 35.9 percent in the vitamins, lactulose, and untreated groups, respectively. The fraction of subjects remaining free of adenomas, estimated by Kaplan-Meier survival curves, was significantly different among the three groups (log-rank chi-squared = 17.138; P < 0.001). Using Cox's regression analysis, treatment was the only variable that significantly contributed to the model (regression coefficient = 0.905; P < 0.001). In conclusion, either antioxidant vitamins or, to a lesser extent, lactulose lower the recurrence rate of adenomas of the large bowel and can be proposed as chemopreventive agents, at least in high-risk individuals.

Back to basics

The Society for Surgery of the Alimentary Tract originated as the Society for Colon Surgery. Therefore, it is appropriate that the dramatic developments in colorectal surgery that have occurred during the life of the Society should be emphasized. Major technical advances are identified as ileoanal anastomoses, colonoscopy, and EEA staplers. Although control of cancer remains a major problem, recent trends in the education and agenda of colorectal surgeons promise a bright future.

Straight ileoanal anastomosis with preserved anal mucosa for ulcerative colitis and familial polyposis

Thirty-two patients were treated with colectomy, mucosal proctectomy, and straight ileoanal anastomosis. Mucosal dissection was performed from the abdominal side, and an anal mucosal brim of 1-2 cm was preserved. Diverting ileostomy was not used, and four patients developed anastomotic leak with pelvic sepsis. Three patients had take-down of the anastomosis for reasons related to the operative method. The remaining patients are all completely continent day and night and have a median stool frequency of 6/24 h 1 year after the operation. The frequency was significantly higher in patients with ulcerative colitis (UC) than in patients with familial polyposis (FP). No dysplasia, ulceration, or stricture formation was found in the preserved mucosa in the UC patients. Regrowth of polyps in the mucosal brim occurred in 10 of 13 FP patients, with atypia in 1. The FP patients had more late complications attributed to extracolonic manifestations of the FP disease.

Vaterian cancer in siblings

The simultaneous occurrence of Vaterian carcinoma in two siblings suggests a genetic influence in their pathogenesis. Their classic clinical presentation of obstructive jaundice and weight loss required pancreaticoduodenectomy for this neoplasm. Pedigree analysis revealed a third sibling who died from an unresectable periampullary malignancy. Neither of the probands exhibited, as late as the seventh decade, evidence compatible with a diagnosis of familial polyposis coli or Gardner's syndrome. Flow cytometry studies revealed an aneuploid distribution in one tumor and tetraploid in the other. The rarity of this neoplasm, in the absence of contributing epidemiologic factors, suggests that this is a pleotrophic manifestation of a cancer-prone genotype.

Management of endoscopically removed malignant colon polyps

The medical records of 87 patients with 89 malignant colorectal polyps removed endoscopically between 1971 and 1983 were reviewed retrospectively. Fifty-five polyps contained carcinoma-in-situ. Four polyps had "pseudo-invasion" by displaced mucosal glands. Thirty polyps contained invasive carcinoma. No patients with carcinoma-in-situ or "pseudo-invasion" had either local residual disease or metastatic disease at the time of colectomy or which was detected during subsequent follow-up. Four patients (14%) with invasive cancer would have been inadequately treated by polypectomy alone, since one had residual disease at the polypectomy site, one had nodal metastases, one had liver metastases at the time of colectomy, and one subsequently developed liver metastases. Three histologic criteria correctly predicted all four cases where residual or recurrent disease was present: involvement of the polypectomy resection margin, lymphatic invasion within the polyp, and poorly differentiated histology. Polyp size, histology (villous adenoma, adenomatous polyp, or villo-adenomatous polyp), or anatomic location did not identify those patients who warranted further therapy. We conclude that polypectomy alone is adequate treatment for polyps containing carcinoma-in-situ. Polypectomy alone is also adequate treatment for most polyps containing invasive carcinoma. However, patients with lymphatic involvement within the polyp, poorly differentiated cancer, or resection margin involvement should probably undergo colectomy.

Surgery based on misdiagnosis of adenomatous polyposis. The Canadian Polyposis Registry experience

The histopathology of 304 patients registered in the Canadian Familial Polyposis Registry (CFPR) with a diagnosis of supposed adenomatous polyposis (AP) was reviewed. The diagnosis was changed in 17 (5.6 percent) of these patients. Group 1 consisted of nine patients who had adenocarcinomas plus multiple tubular adenomas (seven) or metaplastic polyps (two). Eight patients who had no colon cancer comprised Group 2. In these patients, the diagnosis was changed to lymphoid polyposis (2), metaplastic polyps (3), isolated adenomas (2), or juvenile polyposis (1). All 17 patients had had previous colonic resections. Following the change in diagnosis, this treatment was considered inappropriate in 11 patients. Treatment, prognosis, and follow-up of patients and affected family members depend on the type of polyposis syndrome diagnosed. Correct histologic assessment of polyps prior to initial surgery is essential.

Increased populations of endocrine cells in Crohn's ileitis

Hyperplasia of nerves has been described previously in Crohn's disease. To determine whether similar alteration of the enteric endocrine system occurs, endocrine cells of the ileal epithelium were quantified in typical cases of the disease. In the ileum from patients with Crohn's disease, there was an increase in the endocrine cell population, as visualised by immunostaining of chromogranin. Quantification of endocrine cell numbers showed significant increases in both macroscopically uninvolved (i.e. histologically normal) (35.0 +/- 3.8, cells per unit length of muscularis mucosae mean +/- SEM, P less than 0.05) and involved (44.5 +/- 5.5, P less than 0.01) Crohn's disease samples, compared with normal controls (23.7 +/- 3.4). Although individual types of endocrine cell showed slight increases in Crohn's samples, only the enterochromaffin cells in abnormal bowel showed a significantly greater population (normal controls 10.5 +/- 2.3; involved Crohn's 21.3 +/- 4.4, P less than 0.05).

Colorectal polyps and the risk of subsequent carcinoma

Of 323 patients with colorectal polyps that either were larger than 1 cm in diameter or were 1 cm or smaller but had been subjected to biopsy or excision, 20 (6%) had subsequent development of a colorectal carcinoma, an incidence rate of 4.6 per 1,000 person-years of follow-up. These 20 cases of cancer compared with 7.38 cases expected; thus, the risk of colorectal carcinoma in these patients was 2.7 times that in the general population (P less than 0.001). Although risks were greater for certain subgroups of patients, the differences detected were usually modest. We conclude that patients with large colorectal polyps (more than 1 cm in diameter) should be closely followed up after treatment of the initial polyp, regardless of the size, site, or histologic type of the polyp, the age or sex of the patient, or the type of initial treatment (excision or fulguration). Those patients with more than one polyp, especially if more than one segment of the colon is involved, need special attention. Examination of the entire colon is important because the site of development of carcinoma may be distant from the site of the initial polyp.

Dominant inheritance of adenomatous colonic polyps and colorectal cancer

Except in the rare polyposis syndromes, the contribution of heritable factors to the genesis of colorectal cancer and adenomatous polyps is not well understood. We examined the inheritance of susceptibility to colonic polyps and cancer in a large Utah pedigree with multiple cases of common colorectal cancer but no recognizable inheritance pattern among them. Inheritance was clarified, however, by systematic screening for colonic polyps in pedigree members and spouse controls, using flexible proctosigmoidoscopy. One or more adenomatous polyps were found in 21 per cent of family members (41 of 191) but in only 9 per cent of controls (12 of 132) (P less than 0.005). Pedigree analysis was performed with likelihood methods that compared random occurrence of cancer and polyps with autosomal recessive and autosomal dominant patterns of inheritance. The analysis suggested that the observed excess of discrete adenomatous polyps and colorectal cancers was the result of an inherited autosomal dominant gene for susceptibility, rather than an inherited recessive gene for susceptibility or a chance occurrence. This type of inheritance of colorectal polyps and cancer may be more common than previously recognized.

Experience with 1000 colonoscopic polypectomies

Experience with 1000 consecutive polypectomies in 591 patients, from December 1975 to October 1982, is reviewed. There were 633 adenomas, 292 hyperplastic, and 75 miscellaneous polyps. While eight minor bleeding episodes (0.8%) occurred, there were no major complications (perforations or bleeding requiring transfusion). The polyp retrieval rate was 97.9%. Of the 633 adenomas, seven (1.1%) had in situ carcinoma and ten (1.6%) invasive. Eight of the invasive group underwent colon resection with no positive nodes present. Anatomic location demonstrated a shift to the right side of the colon. Three hundred thirty-six (53.1%) were in the rectosigmoid; 134 (21.3%) were in the left colon; 79 (12.3%) were in the transverse colon; and 84 (13.3%) were in the right colon and cecum. Patients who have undergone benign polypectomy are colonoscoped again in 1 year, and, if negative, every 3 years thereafter. Postpolypectomy patients with malignant adenomas require closer observation. Endoscopic polypectomy, with its lower morbidity and mortality, has revolutionized the treatment of the colon polyp. It is also more cost-effective, with outpatient polypectomy being 29 times less expensive and inpatient polypectomy four times less expensive than transabdominal polypectomy.

Technique of colonoscopic polypectomy

Most colonic polyps can be removed colonoscopically from all reaches of the colon, provided that one is experienced with endoscopic morphology and snare electrosurgical techniques. Virtually all pedunculated polyps and the majority of benign sessile polyps can be excised colonoscopically, certain of the larger benign sessile polyps and all malignant sessile lesions still require partial colectomy, if the patient's general condition will permit. Preparation for colonoscopic polypectomy includes thorough mental as well as physical preparation of the patient and the availability of properly functioning endoscopic and snare-cautery equipment. An experienced colonoscopist is one who is not only prepared for the diagnostic possibilities but experienced enough to manage certain of the larger polyps so that laparotomy is limited to those few lesions that are not amenable to safe and total colonoscopic polypectomy.

Distribution of large-bowel cancers detected by occult blood test in asymptomatic patients

A randomized, controlled study on occult blood in stool was conducted in 48,000 asymptomatic participants, ages 50 to 80 years. Those with positive hemoccult test results underwent a complete colonic workup including colonoscopy and, in some cases, an air-contrast barium-enema examination when total colonoscopy could not be accomplished. From April 1976 to December 1980, 113 patients (62 men and 51 women), with an average age of 66 years, were found to have invasive carcinomas of the large bowel: right colon--25 per cent, transverse colon (included both flexures)--9 per cent, descending colon--10 percent, sigmoid and rectosigmoid--42 per cent, rectum--12 per cent, anal canal--2 per cent. The stages of the cancers were: Dukes' A--57 per cent, Dukes' B--21 per cent, Dukes' C--19 per cent, Dukes' D--3 per cent. The findings suggest that a complete colonic workup is required for the detection and diagnosis of large-bowel cancers in asymptomatic patients.

A canine model of gastric and colonic polyps

Polyps were produced in the canine stomach and colon by a surgical technique. In a total of 18 dogs 26 polyps were produced in the stomach or colon. Twenty of the 26 polyps were viable when endoscopically and microscopically examined. Polyps of approximately 1 cm in diameter and 3 to 4 cm in length can be produced without sloughing. The gross and microscopic characteristics of the canine polyp are quite similar to the human condition. Obviously the adenomatous tissue of the polyp head was not reproduced, but this area is not generally cut during polypectomy. The surgical produced polyps appear to be useful as a model to study the effects of electrosurgical cutting and for training in the technique of polypectomy.

Comparative histologic study of adenomas of the large intestine in Japan and England, with special reference to malignant potential

The malignant potential of large-intestinal adenomas varies with size, histologic type, and grade of epithelial atypia in the same way in England and in Japan. Adenomas in England have greater malignant potential than those in Japan because they grow larger and more often show a villous growth pattern. Although the adenoma--carcinoma sequence operates in the same way in the two countries it is suggested that the higher incidence of colorectal cancer in England is due to the greater prevalence as well as the greater size of English adenomas. More studies of the epidemiology and geographic pathology of large-intestinal adenomas are needed to clarify their importance as a predisposing cause of colorectal cancer in low-risk as well as high-risk areas.

Villous adenomas of the colorectum

During a ten-year period 258 patients with villous adenomas were seen at the Massachusetts General Hospital: seventy-four of these patients (29%) had invasive cancer that developed in adenomas. The operative mortality ascribed to removal of benign adenomas was zero, but for cancer arising in villous adenomas it was 3 per cent. Therapy often is difficult because of the size and location of the tumors. Methods of removal have been considered in detail.

The evolution of cancer of the colon and rectum

The malignant potential of adenomas of the colon and rectum varies with size, histological type and grade of epithelial atypia. The adenomatous polyp is usually small and has a low malignant potential, whereas tumors with a villous structure are usually larger and have a much higher cancer rate. Severe atypia is more common in villous adenomas than in adenomatous polyps. Evidence is presented which suggests that most cancers of the colon and rectum have evolved through the polyp-cancer sequence although the majority of adenomas do not becoma cancerous during a normal adult life span. The slow evolution of the polyp-cancer sequence is stressed. The implications of the polyp-cancer sequence for the design of cancer prevention programmes and the study of the aetiology of large bowel cancer are discussed.

Pseudo-carcinomatous invasion in adenomatous polyps of the colon and rectum

The histology of pseudo-carcinomatous invasion in adenomatous polyps of the colon and rectum is described and the appearances are contrasted with those seen in malignant polyps. The recognition of pseudo-carcinomatous invasion is important in the differential diagnosis of benign and malignant polyps of the large bowel. Failure to distinguish it from carcinoma may lead to wrong treatment and false reports of the incidence and prognosis of cancer of the colon and rectum. The evidence suggests that pseudo-carcinomatous invasion may be the result of repeated twisting of the stalk of a polyp which causes haemorrhage and this facilitates the passage of non-malignant adenomatous epithelium through the muscularis mucosae.

Polyps of the rectum and colon

Four hundred and thirty-three patients with adenomatous polyps were examined and followed up. It was found that well differentiated adenomas are stable but dedifferentiated polyps can lead to invasive cancer, usually over a long period of time. Thus the concept of malignant transformation becomes meaningless, and should be replaced by an initial histological evaluation of polyps of the rectum and colon so that their development can be predicted.