Background The current practice of removing adenomatous polyps of the colon and rectum is based on the belief that this will prevent colorectal cancer. To address the hypothesis that colonoscopic polypectomy reduces the incidence of colorectal cancer, we analyzed the results of the National Polyp Study with reference to other published results. Methods The study cohort consisted of 1418 patients who had a complete colonoscopy during which one or more adenomas of the colon or rectum were removed. The patients subsequently underwent periodic colonoscopy during an average follow-up of 5.9 years, and the incidence of colorectal cancer was ascertained. The incidence rate of colorectal cancer was compared with that in three reference groups, including two cohorts in which colonic polyps were not removed and one general-population registry, after adjustment for sex, age, and polyp size. Results Ninety-seven percent of the patients were followed clinically for a total of 8401 person-years, and 80 percent returned...

Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup.

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.

https://acsjournals.onlinelibrary.wiley.com/doi/pdf/10.1002/cncr.2820360944

The evolution of cancer of the colon and rectum.

BACKGROUND. The American Cancer Society, the Centers for Disease Control and Prevention (CDC), the National Cancer Institute (NCI), and the North American Association of Central Cancer Registries (NAACCR) collaborate annually to provide updated information regarding cancer occurrence and trends in the United States. This year's report includes trends in colorectal cancer (CRC) incidence and death rates and highlights the use of microsimulation modeling as a tool for interpreting past trends and projecting future trends to assist in cancer control planning and policy decisions. METHODS. Information regarding invasive cancers was obtained from the NCI, CDC, and NAACCR; and information on deaths was obtained from the CDC's National Center for Health Statistics. Annual percentage changes in the age-standardized incidence and death rates (based on the year 2000 US population standard) for all cancers combined and for the top 15 cancers were estimated by joinpoint analysis of long-term trends (1975-2006) and for short-term fixed-interval trends (1997-2006). All statistical tests were 2-sided. RESULTS. Both incidence and death rates from all cancers combined significantly declined (P < .05) in the most recent time period for men and women overall and for most racial and ethnic populations. These decreases were driven largely by declines in both incidence and death rates for the 3 most common cancers in men (ie, lung and prostate cancers and CRC) and for 2 of the 3 leading cancers in women (ie, breast cancer and CRC). The long-term trends for lung cancer mortality in women had smaller and smaller increases until 2003, when there was a change to a nonsignificant decline. Microsimulation modeling demonstrates that declines in CRC death rates are consistent with a relatively large contribution from screening and with a smaller but demonstrable impact of risk factor reductions and improved treatments. These declines are projected to continue if risk factor modification, screening, and treatment remain at current rates, but they could be accelerated further with favorable trends in risk factors and higher utilization of screening and optimal treatment. CONCLUSIONS. Although the decrease in overall cancer incidence and death rates is encouraging, rising incidence and mortality for some cancers are of concern.

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Annual Report to the Nation on the Status of Cancer, 1975-2006, Featuring Colorectal Cancer Trends and Impact of Interventions (Risk Factors, Screening, and Treatment) to Reduce Future Rates

Dysplasia in inflammatory bowel disease: Standardized classification with provisional clinical applications

An international group of endoscopists, surgeons, and pathologists gathered in Paris for an intensive workshop designed to explore the utility and clinical relevance of the Japanese endoscopic classification of superficial neoplastic lesions of the GI tract. This report summarizes the conclusions of the workshop and proposes a general framework for the endoscopic classification of superficial lesions of the esophagus, stomach, and colon. The clinical relevance of this classification is demonstrated in tables that show the relative proportion of each subtype in the esophagus, stomach, and colon, assessing the risk of submucosal invasion and the risk of lymph node metastases. In the esophagus, stomach, and colon, neoplastic lesions of the digestive tract are called ‘‘superficial’’ at endoscopy when the endoscopic appearance suggests either a small cancer or a noninvasive neoplastic lesion (dysplasia/adenoma). If invasive, ‘‘superficial’’ tumors correspond to the T1 stage of the TNM classification, in which invasion is limited to the mucosa and submucosa. ‘‘Superficial’’ tumors are nonobstructive, usually are asymptomatic, and often are detected as an incidental finding or by screening. In Japan, neoplastic lesions of the stomach with a ‘‘superficial’’ endoscopic appearance are classified as subtypes of ‘‘type 0.’’ The term ‘‘type 0’’ was chosen to distinguish the classification of ‘‘superficial’’ lesions from the Borrmann classification, proposed in 1926 for ‘‘advanced’’ gastric tumors, which included types 1 to 4. Within type 0, there are polypoid and non-polypoid subtypes. The nonpolypoid subtypes include lesions with a small variation of the surface (slightly elevated, flat, and slightly depressed) and excavated lesions. The Japanese Gastric Cancer Association (JGCA) also added a type 5 for unclassifiable advanced tumors. The complete modification for gastric tumors becomes:

H. J. R. Bussey

Papers

The evolution of cancer of the colon and rectum.

Predisposing causes of intestinal cancer.