Clarence K.W. Wong, MD, FRCPC, Gastroenterologist and Clinical Lecturer, Division of Gastroenterology, University of Alberta; Consultant, Cross Cancer Institute, Alberta Cancer Board, Edmonton, AB.

Introduction
Gastrointestinal malignancies collectively account for the greatest number of cancer deaths in Canada.¹ This is particularly evident in the elderly population in which 90% of all new cancers are diagnosed in individuals over the age of 45.² Of these new cancers, one in five are gastrointestinal cancers. As these malignancies are often lethal, improved survival depends on preventive strategies to effectively detect and manage the associated precursor conditions. This paper will review the premalignant conditions associated with three common gastrointestinal cancers. Effective management of conditions leading to esophageal, gastric and colon cancers can greatly reduce the burden of disease among the geriatric population.

Esophageal Cancer
Cancers of the esophagus are lethal, with a death to case ratio of 1.11.¹ Although this estimate is high due to incomplete registration of new cases, it underscores the lack of effective treatment for this disease. Until recently, squamous cell carcinomas were the most common type of esophageal cancer. However, in the last few decades the incidence of esophageal adenocarcinomas has increased exponentially. It is likely that this increase is linked to a rise in incidence of its only known risk factor, Barrett's esophagus.

Another study has contributed to the growing body of evidence linking Helicobacter pylori, to the development of gastric cancers. Uemura et al., prospectively studied 1,526 Japanese patients who had duodenal ulcers, gastric ulcers, gastric hyperplasia or non-ulcer dyspepsia at the time of study enrollment. Of these, 1,246 had H. pylori infection, and 280 did not.

The researchers found that gastric cancers developed in 2.9% of the H. pylori infected individuals and none of the uninfected patients. Among the H. pylori infected patients, those with severe gastric atrophy, corpuscle-predominant gastritis and intestinal metaplasia, were at significantly higher risk for developing gastric cancer.

Source

1. Uemura, N, Okamoto, S, Yamamoto, S et al. Helicobacter pylori infection and the development of gastric cancer. New England Journal of Medicine. 2001; 345:784-789.

Jolie Ringash, MD, MSc
Department of Radiation Oncology,
Princess Margaret Hospital
University Health Network,
Toronto, ON

Background
Esophageal and gastric carcinomas are primarily diseases of older persons. Of 498 new cases of esophageal cancer in Ontario in 1997, 237 (48%) occurred in individuals aged 65 to 79, and 101 (20%) in those over the age of 80. The corresponding numbers for gastric cancer are (of a total of 1,032 cases) 492 (48%) for those aged 65 to 79, and 200 (19%) for those over 80.¹ For all age groups, gastric cancer is decreasing in incidence, with only 2, 800 cases in Canada in the year 2000. In contrast, the incidence of esophageal cancers is gradually increasing (1,350 cases in 2000).^2,3 Adenocarcinoma, primarily of the distal esophagus, has replaced squamous cell carcinoma as the most frequent histology. Tumours of the gastroesophageal junction pose a particular challenge, since management may differ depending on whether the tumour is felt to originate in esophagus or stomach.

Canadian oncologists frequently face difficult treatment decisions in the elderly. Unfortunately, since older patients are usually excluded from clinical trials, evidence for their tolerance of, and response to, therapeutic radiation is limited. Existing reports are limited to retrospective reviews and subgroup analyses, many of which originate in Japan.