Gastric cancer (GC) is one of the most common neoplasias. It holds first place in malignant tumors of the gastrointestinal tract, fourth place in frequency, and second place in death by cancer.1 Incidence rates vary depending on the region or country analyzed. The highest rates are in Japan, with values of 77.9 per 100,000 in men and 33.3 in women. The lowest rates are in North Africa, the United States, and Canada, with rates of 5.9 to 9.0 per 100,000 in men and 2.6 to 5.3 in women.2

In Mexico, GC is the fourth cause of death by cancer in men and the fifth in women,3 whereas the crude GC-associated mortality rate is 8.8%, or 5.0 per 100,000 inhabitants, with a greater predominance in persons above 50 years of age. For the year 2012, GLOBOCAN reported GC as the third cause of death in relation to the different types of cancer. Some geographic areas of the Mexican Republic have higher GC-associated mortality rates, such as the State of Chiapas, with 6.4 per 100,000, compared with Mexico City (4.5 per 100,000), and the State of Mexico (2.5 per 100,000).3

The origin of GC is considered multifactorial.4–6 The frequency of the different neoplasias of the digestive tract worldwide varies in relation to geographic location, ethnicity, genetic and environmental factors, dietary habits, and exposure to carcinogenic agents.7

Diet has a strong influence. The present risk factors described are: salt, salted meat, carbohydrates, and coffee. Fruit, carotene-rich vegetables, vitamin C, and refrigeration for food storage have been described as protective factors.4–6,8

Vegetables contain abundant nitrates that are converted into nitrites by bacteria in the saliva. Nitrites transformed into nitrosamines in the stomach damage the inflamed mucosa. Vitamin C neutralizes the nitrosamines, which is why smoking is also a risk factor, given that it decreases vitamin C levels. Consuming fruits and vegetables, together with cured foods, has a similar protective effect.5 The consumption of capsaicin, the irritating element in chili peppers, has been studied in Mexico and is considered a risk factor for the development of GC.4

Alcohol consumption has a harmful effect on the stomach by sensitizing the mucosa in the presence of carcinogenic agents, and is attributed to the nitrosamine content in alcoholic beverages.9 Smoking has also been described to increase the risk for GC 1.5 to 1.6 times.4 Cigarette smoke contains N-nitrosamines and nitrogen oxides, both gastric carcinogens, because they form free radicals with an elevated oxidizing potential. Another risk factor is infection from viral and bacterial oncogenic agents that trigger chronic inflammatory reactions due to their proclivity for establishing life-long infections.10

The frequency of gastric cancer has been reported to significantly increase after 50 years of age,10,11 rarely presenting in patients under 30 years old. GC mortality is closely related to socioeconomic conditions in the first years of life, consistent with a greater prevalence of Helicobacter pylori (HP) infection in childhood in poor populations.2HP is the main determining factor in the appearance of GC.2,3,5 The risk for developing GC is 6 times higher in the population with HP infection. The appearance of atrophic chronic gastritis, intestinal metaplasia, and dysplasia is postulated to be a long process that takes years or decades.3 A high frequency of GC and its association with HP infection has been identified in the population in the State of Chiapas, Mexico.2

Another risk factor is the Epstein-Barr virus (EBV), which has been detected in an average of 10% of cases in association with GC.9,11 Some of the highest incidence rates are in Latin America: in Chile with 23.6% and in Colombia with 13%. Incidence in Mexico is close to 8%.9

Workplace risk factors from different industries have also been observed in workers exposed to silicon, lead, and asbestos, which irritate the gastric mucosa and act as carcinogens.3,4

The increase in proximal digestive tract cancer in developed countries appears to be related to the increased incidence of Barrett's esophagus.12

A total of 100 cases of GC were detected, and 84 that met the inclusion criteria were included. Sixteen cases were rejected because they had no histologic confirmation, or the clinical history was not complete. Incidence was 2.14 for every 100 oncology patients released from the hospital. Within the time frame of 2007-2014, a variation of new cases per year was observed (fig. 1).

Figure 1.

Number of new cases of patients with gastric cancer seen at the HRAECS, 2007-2014.

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Sociodemographic characteristics

Of all the cases, 41 were men and 43 were women (a 1:1.04 ratio). Mean age was 57.3 years, with a range from 25 to 87 years. Mean age was 58.7 years in men and 55.9 years in women.

Figure 214 shows the municipalities where the patients with GC were from and are those that stand out from a total of 38. Figure 314 shows the socioeconomic zones where the patients with GC were from. Of the 84 cases, 2 were not from the State of Chiapas.

Figure 2.

Municipalities with a greater number of patients with gastric cancer seen at the HRAECS, 2007-2014.

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Figure 3.

Region of origin of the patients with gastric cancer seen at the HRAECS, 2007-2014.

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Table 1 describes the sociodemographic characteristics of the patients.

Table 1.

Sociodemographic characteristics of the patients with GC seen at the HRAECS within the time frame of 2007-2014.

Variables	n	%
Sex
Women	43	51.19
Men	41	48.81
Educational level
Illiterate	17	20.24
Primary school completed or not completed	48	57.14
Secondary school completed or not completed	9	10.71
High school	8	9.52
University	2	2.38
Occupation
Housewife	40	47.62
Farmer	28	33.33
Businessperson	2	2.38
Retired	1	1.19
Employed	4	4.76
Unemployed	9	10.71
Religion
Adventist	2	2.38
Catholic	63	75
Christian	18	21.42
Jehova's Witness	1	1.2
Civil status
Married	49	58.33
Divorced	2	2.38
Single	13	15.48
Common law union	11	13.1
Widowed	9	10.71
Social Security
ISSTECH	1	1.19
IMSS	1	1.19
Seguro Popular	68	80.95
None	14	16.66

Survival

The Kaplan-Meier method was utilized to carry out the survival analysis in the patients that presented with GC15 and it took into account the information of the patients that died, as well as the censored patients. Survival at one, 2, 3, and 4 years was determined. The log-rank test was used in the stratified analysis16 to evaluate the differences between the survival curves. Overall survival in the 84 patients was 67%, showing a one-year survival of 72% and a two to four-year survival of 62%, with a mean survival rate of 38.8% (95% CI: 34.7-42.9). The survival curve differences were not statistically significant (p=0.66) (fig. 4).

Figure 4.

Overall survival of the patients with gastric cancer, seen at the HRAECS, 2007-2014.

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In Mexico, GC is a public health problem. Within the time frame of 2007 to 2014 a total of 84 cases of GC were registered. A study carried out at the Hospital Juárez de México reported 234 cases of GC over a 4-year period (2006-2010).17 The highest incidence worldwide was reported in Japan: 77.9 per 100,000 in men and 33.3 in women.2 Incidence in Mexico is 3.3 per 100,00011 and in Chiapas is 6.4 per 100,000.3 In the present study, incidence was 2.14 for every 100 oncology patients released from the HRAECS. In Chiapas, malignant tumors are reported as the second cause of death, with a rate of 52 per 100,000 inhabitants.18

Stomach cancer mostly affects advanced-age persons, with a reported age between 65 and 69 years at the time of diagnosis.17,19 In Mexico, the reported age is from 50 years and in the present study, which included patients 25 years of age with the diagnosis, the mean age was 57 years.

For the year 2008, reports indicate that the frequency of GC had a man:woman ratio of 1.2:1.20 We found a minimal difference, with a man:woman ratio of 1:1.04. Likewise, persons with blood type A have been described as having a greater risk for presenting with GC.3,11 Of the patients in our study, 73.91% had blood type O.

Weight loss and anorexia syndrome have been described as symptoms of patients with GC.4,6 We observed body mass indices of our patients within normal parameters, but there were also patients that had considerable weight loss: in women the lowest weight was 32kg, and in men 33.5kg. The mean hemoglobin value in men was 10.81g/dl, and in women it was 10.99g/dl, far below normal values.

A family history of cancer, and specifically of GC, have been described as risk factors for presenting with GC.1,5,7,21 In our study those percentages were 25.28 and 8.04%, respectively.

The main risk factors associated with GC are HP infection, heavy smoking, and to a lesser degree, alcohol consumption.1,4,21,22 In our results, 35.71% of the patients stated they had been alcoholics and 22.61% said they were smokers. Likewise, we found 10 patients that had related HP infection: 5 were determined through qualitative ELISA testing and 5 through histopathology studies.

Using the study by Roesch-Dietlen et al. as a reference, there was an increase in GC cases in 2009.7 In the present study we also observed an increase, but the most notable one was in 2013.

Ninety-five percent of all gastric neoplasias are adenocarcinomas.1,7,19,21 In a study conducted in Mexico City that compared 4 hospitals, 95.73% of the tumors were adenocarcinomas.22 Of all our cases, 90.16% were classified as adenocarcinomas.

The main treatment for GC is surgical.4 In our study, the majority of the patients were treated exclusively with chemotherapy, whereas surgery was the treatment that was the second in frequency.

Survival is very low in patients with GC5. In a study conducted in Chiclayo, Peru, the authors found survival rates of 31.5% and 53% at 5 years of follow-up,23 whereas our patients at the HRAECS had a survival rate of 62% at 4 years of follow-up.

Our study results did not show a big difference between men and women in relation to GC presentation. Some of the patients with GC were very young, but the age of the majority of patients was similar to that reported in Mexican populations. Regarding risk factors, we could not conclude that there was a relation between HP and GC, given that HP testing was not part of the laboratory studies performed on all the patients. However, we did find that exposure to smoke was a factor present in our patients. GC is an aggressive neoplasia that mostly affects the advanced-age population, but it also affects young persons. A younger age at the time of diagnosis has been reported in Mexico, compared with other countries. There are many risk factors for developing GC, and alcohol consumption and smoking are the most outstanding non-pathologic factors. Another important factor is a family history of GC or any other neoplasia. In general, GC is diagnosed at advanced stages, conferring a poor outcome on the patient and underlining the importance of creating prevention, early detection, and disease control strategies.

An epidemiologic analysis was carried out in relation to the cases of GC seen at the HRAECS, in the State of Chiapas.

GC is an aggressive neoplasia that mostly affects the advanced-age population, but it can also present in young persons.

In the present analysis, we found that the consumption of alcohol and tobacco played an important role in the development of GC, as did a family history of any type of cancer.

In general, GC is diagnosed at advanced disease stages, resulting in poor patient prognosis. Therefore, developing a plan for the prevention, early detection, and control of the disease in the State of Chiapas is a reasonable endeavor.

The authors received financial support from the E022IV010 budget program “Fomentar la investigación en Salud” from the Health Department's Centro Regional de Alta Especialidad de Chiapas.

The authors declare that there is no conflict of interest.