Date of Award

11-2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Dr. Abdulbari Bener

Second Advisor

Dr. Enyioma Nwaogu Obineche

Third Advisor

Dr. Mouza AI-Sharhan

Abstract

Colorectal cancer represents one of the most common causes of mortality in the world. A major number of populations develop an adenoma by the age of 40s. Over the past years, it has become clear that genetic factors are of crucial importance in colorectal tumorigenesis. Familial adenomatous polyposis (FAP) is responsible of developing numerous colorectal cancers cases by causing mutations in the germline in adenomatous polyposis coli (APC) genes.

Colon cancer is considered the second most frequent cause of death in most of the Western countries. Colonic cancer is common in women and rectal in men. It arise in adenomatous polyps and is associated with both genetic and environmental factors that affect the development of the polyp.

The aim of the present study was to analyze a set of environmental and genetic variables that can help in predicting the factors affect the formation of colorectal cancer. Additionally, the aim of this study was to define the epidemiology of colorectal cancer in AI-Ain city in the United Arab Emirates and compare it with regional and international literatures. Also, to examine the pattern of survival in relation to the initial diagnostic stage and histopathologic grades. The study focus on the comparison between patients with colorectal disease and non-colorectal disease on the level of environmental by studying their life style and on the level of genetics by screening part of the DNA (APC gene) for any mutation that cause colorectal cancer.

The study was conducted in the Preventive Medicine Department, Al-Ain Medical District in AI-Ain and Tawam Hospitals. The study included 65 patients with colorectal disease gone for endoscopy, and 65 control patients with non-colorectal disease, and 7 patients diagnosed with colorectal cancer during 2000 year. The retrospective study included all colorectal cancer patients diagnosed or referred to these two hospitals between January 1985 and December 1998. The retrospective study consisted of 114 patients with colorectal carcinoma admitted to both hospitals.

Although this study is not intended for generalization of the DNA mutation to the whole UAE population, but without any doubt this study would be a representative sample of concurrent screening of DNA mutation in the community. The first part of the study was epidemiological data presenting the life style of the patients through out the questionnaire to compare between the two groups in their nutritional habitat, while the second part of the study focussing on detecting the DNA mutations in the germline of the APC gene to know the cause of colon cancer formation whether environment or genetical.

In this study three systems of primers are used depending on the frequencies of mutations observed in the APC gene, the set of primers designed for system 1 amplified 91 bp flanking codon 1309 with incidence of 17% Familial Adenomatous Polyposis families mutation in this region of DNA. System 2 amplifies DNA fragment of APC gene flanking codon 1061 with incidence of approximately 8% mutation, while system 3 amplify flanking codon 1546 for mutation approximately 1.1 % Familial Adenomatous Polyposis family member.

During the last twelve years a total 114 patients with colorectal cancer were diagnosed and referred to Tawam and AI-Ain hospitals in AI-Ain City, Abu Dhabi Emirate, in UAE. Mean annual incidence was 12 patients / year. The overall incidence is 6.6 / 100,000 patients. There were 77 males (67.5%) and 37 females (32.5%), and total of national and Omani patients were 44 (38.6%) and non-UAE national were 70 (61.4%).

The mean age at the time of diagnosis is 46.6±11.8 years and with the median age of 47 years. The age of highest occurrence was between 41-50 years and accounted for 34.2%, while the lowest accounted for 7.9 % of the patients were below the age of 30 years.

The main presenting symptoms were abdominal pain (29.1%), and change of bowel habits (15.4%) while the predominant sign was rectal bleeding (17.2%).

The mean overall survival time was 30.89 ± 11.72 months with a range of 6 and 120 months. The mean survival time was significantly shorter for patient aged 40 years or less (p

The predictor was significant as shown by the log rank test (p

The study showed that the highest occurrence of colorectal cancer is about 45-60 years in the study population. The most common presenting symptoms was abdominal pain followed by abdominal bleeding. The rectum and sigmoid were the most common sites of tumor and our results are consistent with studies from UK and USA. Finally, the most of the lesions were seen in Duke B and C.

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