B C Morson

Bio: B C Morson is an academic researcher from Memorial Sloan Kettering Cancer Center. The author has contributed to research in topics: Ulcerative colitis & Cancer. The author has an hindex of 29, co-authored 44 publications receiving 8835 citations.

The evolution of cancer of the colon and rectum.

Abstract: 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.

Long-term risk of colorectal cancer after excision of rectosigmoid adenomas

Abstract: Background and Methods Surveillance by repeated colonoscopy is currently recommended for patients with colorectal adenomas. We assessed the long-term risk of colorectal cancer after rigid-instrument sigmoidoscopy and polypectomy in 1618 patients with rectosigmoid adenomas (tumors of the rectum or distal sigmoid colon) who did not undergo surveillance. A total of 22,462 person-years of observation were accrued (mean, 14 years per patient). Results The incidence of subsequent rectal cancer in these patients was similar to that in the general population (standardized incidence ratio, 1.2; 95 percent confidence interval, 0.7 to 2.1). Most rectal cancers developed in patients whose adenomas had been inadequately removed; the risk was very low after complete removal. The risk of subsequent colon cancer depended on the histologic type, size, and number of adenomas in the rectosigmoid. Among 842 patients with a rectosigmoid adenoma that was tubulovillous, villous, or large (≥1 cm), colon cancer developed...

The grading of rectal cancer: historical perspectives and a multivariate analysis of 447 cases.

Abstract: The grade of a tumour is gauged on the subjective assessment of a number of histopathological parameters. The problems associated with this exercise were viewed from a historical perspective and survival analysis of 447 patients receiving surgery for rectal adenocarcinoma was undertaken. Only deaths from rectal adenocarcinoma were included as events in the survival analysis. Seven grade-related parameters were scored by one observer. A grading system was constructed using the Cox regression model. The variables in the best-fitting parsimonious model comprised lymphocytic infiltration, tubule configuration and pattern of growth. Scores were derived from the model and a four grade system was created in which the groups were of similar size. Good reproducibility of the selected histopathological parameters was demonstrated. Grade-related parameters were then allowed to compete with stage-related parameters in an overall model of pathological prognostic categories. The parameters selected in the best model were number of affected lymph nodes, the presence of lymphocytic infiltration and extent of spread through bowel wall. A set of five prognostic categories was developed from this model.

Rectal biopsy as an aid to cancer control in ulcerative colitis.

Abstract: There is general agreement that malignant change in ulcerative colitis mostly occurs in those patients whose large intestine is totally involved and have a history of symptoms for more than 10 years. Having thus defined the population of colitics most at risk the problem remains of identifying the individual patient destined to get carcinoma. There is yet no evidence that all the population at risk will eventually develop malignant change. It has been previously pointed out that some test is required which will decide that a patient with ulcerative colitis has entered a precancerous phase (Morson, 1966). The detection of epithelial changes suggestive of precancer or carcinoma in situ in rectal biopsies from patients with ulcerative colitis prompted an investigation into the incidence and extent of such changes in colectomy specimens removed for colitis with and without malignant change. The results of this enquiry are reported here as well as an analysis of the first nine patients in whom the diagnosis of precancer was made in a rectal biopsy and played an important part, together with clinical and radiological observations, in the subsequent decision to perform total proctocolectomy.

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

Abstract: 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...

Patterns of Cancer Incidence, Mortality, and Prevalence Across Five Continents: Defining Priorities to Reduce Cancer Disparities in Different Geographic Regions of the World

Abstract: Efforts to reduce global cancer disparities begin with an understanding of geographic patterns in cancer incidence, mortality, and prevalence. Using the GLOBOCAN (2002) and Cancer Incidence in Five Continents databases, we describe overall cancer incidence, mortality, and prevalence, age-adjusted temporal trends, and age-specific incidence patterns in selected geographic regions of the world. For the eight most common malignancies-cancers of lung, breast, colon and rectum, stomach, prostate, liver, cervix, and esophagus-the most important risk factors, cancer prevention and control measures are briefly reviewed. In 2002, an estimated 11 million new cancer cases and 7 million cancer deaths were reported worldwide; nearly 25 million persons were living with cancer. Among the eight most common cancers, global disparities in cancer incidence, mortality, and prevalence are evident, likely due to complex interactions of nonmodifiable (ie, genetic susceptibility and aging) and modifiable risk factors (ie, tobacco, infectious agents, diet, and physical activity). Indeed, when risk factors among populations are intertwined with differences in individual behaviors, cultural beliefs and practices, socioeconomic conditions, and health care systems, global cancer disparities are inevitable. For the eight most common cancers, priorities for reducing cancer disparities are discussed.

The mesorectum in rectal cancer surgery--the clue to pelvic recurrence?

Abstract: Five cases are described where minute foci of adenocarcinoma have been demonstrated in the mesorectum several centimetres distal to the apparent lower edge of a rectal cancer. In 2 of these there was no other evidence of lymphatic spread of the tumour. In orthodox anterior resection much of this tissue remains in the pelvis, and its is suggested that these foci might lead to suture-line or pelvic recurrence. Total excision of the mesorectum has, therefore, been carried out as a part of over 100 consecutive anterior resections. Fifty of these, which were classified as 'curative' or 'conceivably curative' operations, have now been followed for over 2 years with no pelvic or staple-line recurrence.