Dietary Factors and the Risk of Gastric Cancer in Mexico City
Mary H. Ward
1
2
Lizbeth Lopez-Carrillo
0
2
0
Institute Nacional de Salud Publico
,
Col. Sta. Maria Ahuacatitlan, C.P., Cuernavaca, Morelos, Mexico. Reprint requests to Dr. Lizbeth L6pez-Carrillo
,
Instituto Nacional de Salud Publico, Av. Universidad no. 655, Col. Sta. Maria Ahuacatitlan
,
C.P. 62508 Cuernavaca, Morelos
,
Mexico
1
0ccupational Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute
,
Bethesda, MD
2
Received for publication February 18
,
1998, and accepted for publication September 25, 1999. Abbreviations: Cl, confidence interval; OR, odds ratio; SES, socioeconomic status
Dietary factors play an important role in gastric cancer risk but have not been investigated extensively in Mexico. The authors conducted a population-based case-control study of gastric cancer in the Mexico City, Mexico, metropolitan area in 1989-1990. A total of 220 patients with historically confirmed gastric adenocarcinomas were interviewed. Controls were an age-stratified random sample of residents of the Mexico City metropolitan area. The dietary questionnaire was a 70-item semiquantitative food frequency adapted for the Mexican diet. Odds ratios were calculated for quartiles of consumption of food groups and were adjusted for age, gender, calories, chili pepper intake, cigarette smoking, socioeconomic status, added salt, and history of peptic ulcer disease. There was approximately a threefold increased risk of gastric cancer for frequent consumption (highest quartile) of both fresh meat (odds ratio (OR) = 3.1) and processed meat (OR = 3.2). Odds ratios were also significantly elevated for frequent consumption of dairy products (OR = 2.7) and fish (OR = 2.2). The authors observed a decreasing gradient of risk with increasing frequency of vegetable consumption due to a significant inverse trend for the yellow and orange vegetables. High intake of citrus fruits showed a slight inverse association. Consumption of salty snacks more than twice per month was associated with an 80 percent increased risk, and there was a significant positive trend. These findings are consistent with many studies around the world that indicate important roles for salt, processed meats, and vegetable consumption in gastric cancer risk. Am J Epidemiol 1999;149:925-32. case-control studies; diet; stomach neoplasms
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Gastric cancer is the second most frequent cause of
cancer death in Mexico (1). Mortality from gastric
cancer has decreased dramatically in developed countries
over the past 40 years. In contrast, over the same time
in Mexico and among some Hispanic groups living in
the United States, mortality rates of this cancer have
remained relatively unchanged (2). Gastric cancer
incidence rates vary by more than 20-fold around the world;
differences in dietary patterns may explain much of the
variation in rates across countries. Infection with the
bacterium Helicobacter pylori, which causes
inflammation of the gastric mucosa, is a risk factor for gastric
cancer (3). However, H. pylori infection may not be
sufficient to cause this cancer because only a small
percentage of those infected develop this disease.
Dietary factors are thought to play a role as cofactors in
the progression from gastritis to gastric cancer (3,4).
Consistently increased risks have been found for
diets low in vegetables and fruit (5-8) and high in salt
or salt-preserved foods (5, 6). Other studies found
increased risks for diets high in meats processed with
salt or nitrite and for overall meat intake (4, 6, 9-12).
Lack of refrigeration has been established as a risk
factor (4). Other dietary factors possibly associated with
an increased risk include a high caloric intake,
hightemperature cooking methods for meats, and
consumption of smoked foods (4).
We conducted a population-based case-control study
of gastric cancer in the Mexico City metropolitan area
and reported previously that chili pepper consumption
was a strong risk factor for gastric cancer (13). Here
we report on the association of the intake of meat and
other foods and gastric cancer risk.
MATERIALS AND METHODS
The methods were previously described in detail
(13). Briefly, 267 newly diagnosed cases of gastric
cancer in patients aged 20 years and older were identified
between September 17, 1989, and June 30, 1990, in 15
metropolitan area hospitals in Mexico City. These cases
represented approximately 80 percent of those reported
to the Mexican National Cancer Registry in the same
period. Twenty-two (8.2 percent) of the identified cases
were unavailable for interview. A further 20 cases (7.5
percent) were excluded because the pathology material
could not be obtained, and five cases (1.9 percent) were
excluded because their tumors were not
adenocarcinomas of the stomach, leaving 220 cases confirmed as
gastric adenocarcinomas. The confirmed
adenocarcinomas were further classified according to Lauren (14)
into the intestinal type (98 cases), the diffuse type (95
cases), an (...truncated)