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| ORIGINAL ARTICLE |
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| Year : 2020 | Volume
: 4
| Issue : 3 | Page : 115-119 |
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Diet and gastric cancer
Khushboo Dewan1, Renu Madan2, Prashant Sengupta3, Ashish K Mandal1
1 Department of Pathology, Dr. Baba Saheb Ambedkar Medical College and Hospital, Rohini, Maharashtra, India
2 Department of Pathology and Lab Medicine, Venkateshwar Hospital, New Delhi, India
3 Department of Pathology, Command Hospital (SC), Pune, Maharashtra, India
| Date of Submission | 08-Nov-2019 |
| Date of Decision | 20-Sep-2020 |
| Date of Acceptance | 02-Nov-2020 |
| Date of Web Publication | 26-Nov-2020 |
Correspondence Address:
Khushboo Dewan
Department of Pathology, Dr. Baba Saheb Ambedkar Medical College and Hospital, Sector-6, Rohini, New Delhi - 110 085
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/oji.oji_47_19
Context: Gastric cancer is the fifth most common malignancy, with a high incidence in Eastern Asian countries. Diet is an important risk factor in the genesis of gastric cancer, and the fact that it is modifiable warrants it to be studied extensively in relation to various clinicopathological parameters of gastric cancer. Aims: The present study was undertaken to study the dietary habits (vegetarian/nonvegetarian) among gastric carcinoma patients in the Indian context. Materials and Methods: We studied 100 consecutive cases of gastric carcinoma excluding tumors at gastroesophageal junction. Clinical data regarding food habits in the patients were collected by personal enquiry. Pathological characteristics including size, site, gross appearance, Lauren's histological type, and the World Health Organization (WHO) histological type were noted. Data analysis was done using Chi-square test. Results: Sixty-nine percent of gastric cancer patients were vegetarians and 31% were nonvegetarians. Statistically significant association between nonvegetarian diet and gastric cancer location at the lesser curvature was found (P ≤ 0.001). No statistically significant association between diet and gross appearance, Lauren's, and WHO histological type of gastric cancer was found. Conclusions: For anatomical locations, most gastric cancers located at lesser curvature had been developed among nonvegetarian patients, whereas we did not observe diet to be related to gross appearance and histological type of gastric carcinoma.
Keywords: Association, clinicopathological factors, diet, gastric cancer
How to cite this article:
Dewan K, Madan R, Sengupta P, Mandal AK. Diet and gastric cancer. Oncol J India 2020;4:115-9 |
| Introduction | |  |
Worldwide, gastric cancer is the fifth most common malignancy, after cancer of the lung, breast, colorectum, and prostate, and the third most common cancer causing death.[1],[2] In 2015, there were 1.3 million incident cases of stomach cancer and 819,000 deaths worldwide.[2] Two-thirds of these cases occur in the developing countries, with Eastern Asia leading the race.[1] In fact, in India, gastric cancer stands third when ranked by the number of incident cases in both sexes, after breast cancer and lip and oral cavity cancer.[2] The differences in the risk of developing gastric cancer among various regions are presumed to be related to diet and infection. Certain food preparations peculiar to different regions of the world have been reported to be associated with gastric cancer.[3] Diets rich in salt and smoked foods have been found to be associated with increased risk of gastric cancer.[4],[5] On the contrary, diets rich in fruits and vegetables may be associated with a reduced risk of cancer.[4],[6],[7] Interestingly, a population-based case–control study found nonvegetarian diet to increase the risk of developing adenocarcinomas of the gastric cardia when compared to vegetarian diet.[8]
The latest TNM classification by the American Joint Committee on Cancer 8th ed.ition has classified proximal gastric carcinoma depending on the location of tumor epicenter and the gastroesophageal junction (GEJ) involvement. If the tumor epicenter is in the lower thoracic esophagus or GEJ, or within the proximal 5 cm of stomach (i.e., cardia) with the tumor mass extending into GEJ or distal esophagus, it is classified as esophageal tumor. If the epicenter is >5 cm distal to the GEJ, or within 5 cm of GEJ, but does not involve GEJ or esophagus, it is classified as gastric carcinoma.[9]
Gastric carcinomas have been classified histologically according to the Lauren's classification system into two types that are clinically and epidemiologically distinct – intestinal and diffuse. The Lauren's intestinal type is well differentiated and contains neoplastic cells arranged in a tubular architecture. Lauren's diffuse type is poorly differentiated and is characterized by infiltrating pattern of growth causing thickening of the stomach wall (”linitisplastica or leather bottle appearance”), rather than a discrete mass of fungating or ulcerative outgrowth. The intestinal type is more common in older people in high-risk regions, is more closely related to environmental factors such as diet, Helicobacter pylori infection, and lifestyle, is associated with the lesions of the precancerous cascade such as gastric atrophy and intestinal metaplasia, and has a better prognosis than its counterpart. The diffuse type is more frequent in younger females with genetic susceptibility and blood group A.[10],[11] Gastric carcinomas composed of both intestinal and diffuse components are classified as mixed type.[7]
According to the World Health Organization (WHO) classification, based on the predominant histologic pattern, four major types of gastric cancers are tubular, papillary, mucinous, and signet ring cell carcinoma.[12] Tubular adenocarcinoma is the most common histologic type and comprises branching tubules of varying sizes, often containing intraluminal mucin, nuclear, and inflammatory debris. Papillary adenocarcinoma is characterized by epithelial projections with a central fibrovascular core. Mucinous adenocarcinoma is characterized by tumor cell clusters and glands with the presence of extracellular mucinous pools in at least 50% of tumor volume. Signet ring cell carcinoma shows th presence of dyscohesive or small clusters of malignant cells containing intracytoplasmic mucin in >50% of the tumor and has a poor prognosis.[12],[13]
Diet is an important risk factor in the genesis of gastric cancer and can be modifiable. Hence, it warrants to be studied extensively in relation to various clinicopathological parameters of gastric cancer. With this background, the present study was undertaken to study the dietary habits (vegetarian/nonvegetarian) among gastric carcinoma patients in the Indian population.
| Materials and Methods | | |
This retrospective study was conducted on a set of 100 consecutive cases of gastric carcinoma reporting to a tertiary care hospital over a duration of 2 years from January 2011 to January 2013. Our sample consisted of both biopsies and proximal and radical gastrectomies performed for gastric adenocarcinoma. For biopsy samples, the site of the tumor on endoscopy was accrued from the requisition forms. Cases operated elsewhere but where request for review of slides was received were also included in the study. Patients of all age groups and both sexes diagnosed with primary gastric adenocarcinoma were included in the study. Patients with GEJ tumors, metastatic tumors to stomach, and gastric cancer who received prior chemotherapy were excluded from the study. Clinical data regarding food habits of the study cases were accrued from the histopathology requisition forms and available patient records and personal enquiry from the patient or his relatives. Vegetarian diets essentially excluded animal products (except dairy products) and emphasized upon fruits, vegetables, grains, legumes, nuts, seeds and soy foods. The nonvegetarian diet, by definition, included meat, poultry, fish, and eggs. Small biopsies were processed in total. Gastrectomy specimens were oriented and external surface inspected. Gross findings such as size, site, gross appearance of tumor, distance from closest cut margins, and number of lymph nodes dissected were recorded. Full-thickness tumor sections were stained with hematoxylin and eosin and studied for morphological characteristics. Histological pattern of the tumor according to the latest WHO classification into tubular, papillary, mucin-secreting, and signet ring cell type was documented. Histological typing according to the Lauren's classification into diffuse, intestinal, and mixed type was done.
Statistically relevant deductions were made after compiling the data. Statistical Package SPSS 10.0 (IBM SPSS Statistics, Chicago, Illinosis) for Windows Student Version was used for statistical analysis. P < 0.05 was regarded as statistically significant.
| Results | | |
A total of 100 consecutive patients of diagnosed gastric cancer were retrospectively reviewed. The baseline characteristics of the patients are mentioned in [Table 1]. The mean age of presentation was 59 years within the age range of 29–82 years. Thirty-one out of the 100 patients were nonvegetarians and 69 were vegetarians. More than 50% of the tumors were located at the antropyloric region (68%) followed by greater curvature and lesser curvature. According to the Borrmann classification for macroscopic appearance of tumors, most of the tumors were ulcerative type (83%) followed by others. On using Lauren's classification for histological typing of gastric tumors, 70% were intestinal, 27% were diffuse, and 3% were mixed type. According to the WHO Classification System for Histological Typing, most of the patients were tubular (87%), and other variants such as signet ring cell carcinoma, mucin-secreting type, and papillary type were seen in a smaller number of patients.
78.6% of the patients with gastric carcinoma located at the lesser curvature (n = 14) were those who consumed nonvegetarian diet, while 79.4% of the patients with gastric carcinoma located at antropyloric region (n = 68) consumed vegetarian diet [Table 2], and these results were statistically significant (P <0.001). No statistically significant association was found between diet consumed and gross appearance, Lauren's histological type, and WHO histological type of gastric carcinoma [Table 2]. However, according to the Lauren's histological type, those patients consumed vegetarian diet had a rising trend of association with intestinal type of gastric carcinoma although statistically insignificant (P = 0.09). | Table 2: Association of diet with anatomical sites and histological subtypes of gastric cancer
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| Discussion | | |
The role of diet in the genesis of gastric cancer has been studied by more than 2000 researchers.[5] This is mainly because dietary factors are modifiable and precise knowledge about the role of diet and its mechanism in causation of gastric cancer can serve as powerful tool in the battle against this malignancy.
Most literature points toward consumption of meat, especially red and processed meat to be a risk factor for the development of gastric carcinoma.[14],[15] This risk further increases in H.pylori-infected patients. However, the increased risk is site specific that is the risk increases only for noncardia gastric carcinoma but not for carcinoma of the gastric cardia.[10] A vegetarian diet, on the contrary, has been suggested to be associated with a reduced risk of gastric carcinoma, irrespective of the anatomical location of the tumor. This protective effect of vegetarian diet in the genesis of gastric carcinoma is reported in both Lauren's intestinal and diffuse type but to a greater degree in Lauren's intestinal type.[15]
The mechanisms by which meat intake increases the risk of gastric cancer are many. Meat contains high levels of heme, fat, and proteins, which release nitrites and nitrates.[12] Saturated fat has been documented to increase the risk, whereas polyunsaturated fat decreases the risk of noncardia gastric cancer.[7] Similarly, increased intake of total protein, animal protein, and cholesterol increases the risk of noncardia gastric cancer.[7] Heme contained in meat releases n-nitroso compounds within the body which are carcinogenic.[10] In addition, these n-nitroso compounds are also formed by nitrosation of amines and amides by nitrites and nitrates contained in meat. Agudo et al. suggested that several foods and food components induce chronic gastric inflammation and thereby increase the risk of gastric cancer.[16]
Cooking of meat at high temperatures (grilling, frying, and barbecuing) and cooking over open flame promote the formation of heterocyclic amines and polycyclic aromatic hydrocarbons, which are again carcinogenic.[12] Salting of meat is a common practice and salt has been proven to independently increase risk of gastric cancer in a dose-dependent fashion.[5] Salt causes destruction of gastric mucosal barrier, leading to gastritis, gastric erosions, and therefore enhances the carcinogenic effects of n-nitroso compounds.[5]
On the other hand, dietary β-carotene, folate, Vitamin B6, Vitamin C, and Vitamin E are inversely associated with risk of gastric carcinoma.[7] In fact, risk of both cardia and noncardia gastric carcinoma and both intestinal and diffuse types is reduced by these nutrients. Vitamin C offers a protective role for risk of gastric carcinoma due to its ability to inhibit intragastric formation of n-nitroso compounds.[7] Vitamin E and β-carotene limit gastric damage due to their antioxidant nature. Folate and Vitamin B12 are important in the methylation of DNA and for DNA replication and repair.[7]
These mechanisms of carcinogenesis of gastric carcinoma by various dietary nutrients highlight that several nutrients that are more concentrated in plant-based diets individually lower the risk for gastric carcinoma while many nutrients found in animal foods individually increase the risk of gastric cancer. Mayne et al. went on to describe that the individual nutrients richly found in animal-based foods and positively associated with the risk of gastric adenocarcinoma were dietary cholesterol, saturated fat, animal protein, Vitamin B12, and dietary nitrite. Plant-based foods rich in fiber, β-carotene, folate, Vitamin C, Vitamin E, and Vitamin B6, and vegetable protein were inversely associated and therefore concluded to be protective for risk of gastric cancer.
In the present study, the observation that most diagnosed gastric cancer patients were vegetarians while only 31% were nonvegetarians possibly points toward an increased consumption of saturated fat and salt and decreased consumption of antioxidant vitamins even in vegetarian diet. Moreover, geographical location could be a possible factor for our such incidental finding of more gastric cancers among vegetarians than nonvegetarians where majority of peoples may be vegetarian and they can be confirmed by future case–control study. In the Indian scenario, with a drift toward busy lifestyles and increased paying capacities, inclusion of the ready-to-eat fast food, packaged foods that use preservatives containing nitrites and salt, and decreased consumption of fresh fruits and vegetables have blurred differences between vegetarian and nonvegetarian diet in relation to gastric cancer.
Studies have found association of meat consumption with the development of noncardia gastric cancer exclusively and not with carcinoma of the gastric cardia.[12] In the present study, tumors of the GEJ as defined by the American Joint Committee for Cancer were excluded. None of the cases included in the study were located at the gastric cardia with or without involvement of the GEJ. All the cases included in the study were documented for the site of cancer antropyloric, lesser curvature, and greater curvature. We found a statistically significant association between consumption of nonvegetarian diet and gastric carcinoma located at the lesser curvature. In earlier published studies, the categorization of gastric cancer based on site has been made into gastric cardia and gastric noncardia tumors. In the present study, we have excluded cases of gastric carcinoma at cardia and found that within noncardia gastric cancer, nonvegetarian diet is associated with gastric cancer at lesser curvature.
In the present study, most of the gastric cancers were ulcerative type according to the Borrmann classification based on gross appearance among both vegetarians and nonvegetarians. No relation between type of diet and gross appearance of tumor was observed. Despite extensive literature search, no previous researchers have studied relation between diet consumed and gross type of gastric carcinoma.
No statistically significant relation between type of diet and the histological type of gastric cancer according to both Lauren's classification and WHO classification was observed. This is in contrast to the observation by Correa and Shiao that the Lauren's intestinal type of gastric adenocarcinoma is associated with environmental factors including diet.[17] However, the absence of association between type of diet consumed and histological type of gastric cancer has also been observed by other researchers.[12] The European Prospective Investigation into Cancer and Nutrition study did not find any relation between meat intake and Lauren's histological type.[18] Similarly, Lunet et al. did not report any association between intake of fruits and vegetables and Lauren's histological type, although they did find that intake of fresh fruits and vegetables is inversely associated with gastric cancer genesis.[19] Despite extensive search, we did not find any data on relation between diet and WHO histological type of gastric cancer.
The present study has limitations as it is a retrospective study with a small sample size, with most of the data accrued from case records, and the study has not taken into consideration any change in food habits of the subjects overtime; therefore, results are only hypothesis generating and need to be confirmed in prospective, larger population sized studies.
| Conclusions | | |
We conclude that most of the gastric cancers located at lesser curvature had been developed among nonvegetarian patients. However, we did not observe diet to be related to gross appearance and histological type of gastric carcinoma. We incidentally found that most of the gastric cancer patients are of vegetarians which may be due to geographical location where most of the peoples will be vegetarians which need to confirm by future case–control study.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]
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