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July 2007, Volume 57, Issue 7

Original Article

Association of helicobacter pylori with carcinoma of stomach

Muhammad Arif  ( Department of Pathology, Sindh Medical College, Karachi )
Serajuddaula Syed   ( Department of Pathology, Sindh Medical College, Karachi )

Abstract

Objective: To note the association of Helicobacter pylori in patients having carcinoma of stomach.

Methods: A descriptive study was carried out at the Department of Histopathology, Ziauddin Medical University, Karachi from April 1992 to May 1998. Histological evaluation of 50 cases of carcinoma of stomach was compared with 50 cases each of chronic gastritis and histological normal gastric mucosa. Only those cases of carcinoma of stomach were included that contained sufficient non-neoplastic mucosa in addition to tumour tissue. Three glass slides with serial sections of each case of carcinoma of stomach, chronic gastritis and normal gastric mucosa were freshly cut and stained with H&E, PAS and Giemsa stains. All slides were examined by light microscopy.

Results: Helicobacter pylori were identified in 35 cases (70%) of carcinoma of stomach, in 42 cases (84%) of chronic gastritis, and in 12 cases (24%) of normal gastric mucosa. The presence of H. pylori in cases of carcinoma of stomach and chronic gastritis was highly significant (P<0.001) as compared to normal gastric mucosa. Chronic gastritis was observed in the non-neoplastic mucosa in 48 cases (96%) with carcinoma of stomach. Of 50 cases with carcinoma of the stomach, intestinal type of carcinoma was found in 30 cases (70%), and diffuse type in 15 cases (30%). No significant difference was noted in the prevalence of H. pylori between intestinal type (69%) and diffuse type (71 %) gastric carcinoma. Significant Helicobacter pylori associated chronic gastritis was observed in intestinal type (94%) and diffuse type (100°/x) of gastric carcinoma. The prevalence of H. pylori was insignificant in the presence or absence of mucosal atrophy and intestinal metaplasia in both types of gastric carcinoma.

Conclusion: A significant number of H. pylori were found in patients of carcinoma of stomach. Both intestinal and diffuse types of gastric carcinoma showed strong association with H. pylori. Chronic gastritis appears to be the background lesion while atrophy and intestinal metaplasia indicate long term infection (JPMA 57:337:2007).

Introduction

Helicobacter pylori is a gastric pathogen.1 This bacterium is the commonest causative agent of chronicgastritis and peptic ulcer. Long term infection with this organism is considered a risk factor in the development of carcinoma of stomach.2,3Carcinoma of stomach is the second common estcancer in the world and carries a bad prognosis.4Various environmental and dietary factors have been investigated as agents in the pathogenesis of carcinoma of stomach. Butwith the discovery of H. pylori in human stomach, an inflammation-related carcinogenesis has emerged in which this bacterium is implicated in the causation ofgastric carcinoma.5The epidemiological features of H.pylori and carcinoma of stomach are parallel in different populations of the world. Several studies have suggested that H. pylori is a risk factor in the development of carcinoma stomach.2-5 This study was conducted toinvestigate the association of H. pylori with carcinoma ofstomach.

Patients and Methods

The study included 50 consecutive cases of carcinoma of stomach diagnosed at the department of histopathology, Ziauddin Medical University Karachi from April 1992 to May 1998. For comparison 50 cases of chronic gastritis and 50 cases of histological normal gastricmucosa were taken as controls. The controls were selected from the same period as the cases. The inclusion criterion of carcinoma of stomach cases was the biopsies which in addition to tumour contained area of non-neoplastic tissue, while biopsies ortissues of gastric cardiac region were excluded. Similarly those biopsies of control cases of chronic gastritis andhistologically gastric mucosa were included that contained well oriented sufficient amount of lamina propria. Fresh sections were cut from each paraffin tissue block of the cases included in the study. For each case of carcinoma of stomach, chronic gastritis and histologically normal gastricmucosa, three glass slides with serial tissue sections were prepared for 03 different stains. The stains used wereHaematoxylin & Eosin, Periodic Acid-Schiff and Giemsa.    All the stained tissue slides of carcinoma of stomach,chronic gastritis and histological normal gastric mucosa were examined by light microscopy. Carcinoma of stomach was typed into intestinal and diffuse varieties according to Lauren'sclassification 6; in intestinal carcinoma cohesive malignant cellclusters form glands with distinct lumina, where as diffuse typecarcinoma shows dissociate neoplastic cells which lackglandular lumina. In chronic gastritis, grading of density ofchronic inflammation, active inflammation (neutrophils),atrophy, intestinal metaplasia and H. pylori was done intonormal, mild, moderate, and marked in the guidelines of updated Sydney System aided by the provision of visualanalogue scale.7 The histological parameters were assessed at a time in a particular or combination of stains. The histological finding of cases of carcinoma of stomach, chronic gastritis and histological normal gastric mucosa were entered in performaI, II and III respectively. Frequency and percentage were computed for qualitativeand categorical variables (gender, densities of H. pylori,morphological types of carcinoma of stomach), and meanand standard deviation for quantitative variable (age). Test of proportion was used for comparison of qualitative variable in three groups (Carcinoma of stomach, chronicgastritis and normal gastric mucosa). Analysis of variance(ANOVA) was applied for comparison of age (Mean ± S.D.)in three groups (Carcinoma of stomach, chronic gastritisand normal gastric mucosa). In all statistical analysis only Pvalue <0.05 was considered significant.

Results

The age of patients ranged from 20 to 75 years witha mean age of 49 +15.5 years which was similar to both types of controls (chronic gastritis and normal gastricmucosa). However, the patients of gastric carcinoma were older than chronic gastritis and normal gastric mucosa. The age and gender distribution of all 3 groups is shown in Table1. In all three groups gastric antrum was the predominant anatomical site.H. pylori was identified in 35 cases (70%) ofcarcinoma of stomach, in 42 cases (84%) of chronicgastritis, and in 12 cases (24%) of normal gastric mucosa.The prevalence of H. pylori in carcinoma of stomach andchronic gastritis was highly significant (p<0.001) ascompared to normal gastric mucosa. Chronic gastritis wasseen in the non-neoplastic mucosa in 48 cases (96%) ofcarcinoma; and thirty (69%) of these had moderate chronicinflammation. Mucosal atrophic changes were seen in 41cases (82%) of carcinoma with predominance of mild grade.Of 19 cases (38%) with intestinal metaplasia in carcinoma

Gastritis and Normal Gastric Mucosa cases.

 

Carcinoma

of stomach

Chronic

Gastritis

Normal Gastric

Mucosa

 

(n=50)

(n=50)

(n=50)

AGE (Years):

20 75

10 70

19 75

Range

**

   

Mean t S.D.

49 t 15.5

39 t 15.3

44 t 15.0

SEX: Males

30(60%)

27(54%)

25 (50%)

Females

20(40%)

23(46%)

25 (50%)

**Significant (Pa0.01) as compared to Chronic Gastritis.

 

Table 2. Densities of H. pylori in Carcinoma of stomach, Chronic Gastritis and Normal Gastric Mucosa cases.

Densities of

H. pylori

Carcinoma

of stomach

(n= 50)

Chronic

Gastritis

(n= 50)

Normal Gastric

Mucosa

(n= 50)

Normal

15 (30%)

8(16%)

38(76-/.)

Mild

20(40-/.)

14(28-/.)

12(24-/.)

Moderat

12(24-/.)

13(26-/.)

000 (%)

Marked

3 (6%)

15 (30%)

000 (%)

Difference between Carcinoma of stomach, chronic Gastritis and Normal Gastric Mucosa were

Table 3. Prevalence of H. pylori according to morphological variables of Gastritis in Carcinoma of stomach cases according to type of cancer.

Morphological varibales

(n=35)

H.pylori

Number +ve (%)

(n=15)

H.pylori

Number +ve (%)

Chronic gastritis

33 22 (67)

15 11 (73)

Active inflammation

12 9 (75)

4 4 (100)

Atrophy

26 17 (65)

15 11 (73)

Intestinal Metaplasia

13 8 (62)

6 5 (83)

Table 4. Topographical distribution of atrophy and intestinal metaplasia with prevalence of H. pylori in Carcinoma of stomach cases according to type of Cancer.

**** TYPE OF CANCER ****

Morphological variables

site of biopsies

Atrophy:

H.pylori

Number

+ve (%)

Number

H.pylori

+ve

(%)

Body / Fundus

4 3

(75)

7

5

(71)

Antrum

22 14

(64)

8

6

(75)

Intestinal Metaplasia

         

Body / Fundus

1 1

(100)

2

2

(100)

Antrum

12 7

(58)

4

3

(75)

group, 16 cases (84%) had mild to moderate metaplasia. The density of H. pylori showed mild grade in most cases (57%) of gastric carcinoma which was significantly different (P <0.01) from grades of densities in control subjects (Table 2). The biopsy site (antrum, body,fundus) had no influence in the occurrence of bacteria in all the three groups.

In fifty cases of carcinoma of stomach, intestinal type was found in 35 cases (70%), and diffuse type in 15

significant (Pa0.01).

**** TYPE OF CANCER ****

Intestinal

Diffuse

Intestinal (n=35)

No significant difference.

group, 16 cases (84%) had mild to moderate metaplasia.The density of H. pylori showed mild grade in most cases(57%) of gastric carcinoma which was significantly different (P<0.01) from grades of densities in controlsubjects (Table 2). The biopsy site (antrum, body,fundus) had no influence in the occurrence of bacteria in all the three groups.In fifty cases of carcinoma of stomach, intestinaltype was found in 35 cases (70%), and diffuse type in 15 cases (30%). Helicobacter pylori were seen in 24 of 34cases (69%) of intestinal type, and 11 of 15 cases (71%) ofdiffuse type carcinoma. No significant difference was notedin the prevalence of H. pylori between intestinal and diffuse type of carcinoma. The mean age in intestinal type was 50years, and 44 years in diffuse type. Young age of diffuse type carcinoma was significant (P<0.01). Males werepredominant in both types of gastric carcinoma. Chronic inflammation was noted in the non-neoplastic mucosa in 33of 35 cases (94%) of intestinal type and 100% of diffuse type carcinoma. Atrophic mucosal changes were present in26 of 35 cases (74%) of intestinal and all 15 cases of diffuse type. Mild to moderate grade of intestinal metaplasia wasseen in 11 of 13 cases (85%) with intestinal type and 05 of06 cases (83%) with diffuse type carcinoma. There was nosignificant difference in the prevalence of H. pylori in the morphologic variables of gastritis (Table 3). Mucosalatrophy and intestinal metaplasia in intestinal type was mostly  observed in the antrum. Same morphology showed almost equal distribution in diffuse type carcinoma.Anatomical site had no influence of H. pylori in atrophy andmetaplasia in both type of gastric carcinoma (Table 4).

Discussion

In this study the association of H. pylori with carcinoma of stomach was investigated. Gastric carcinogenesis is a multi step and multi factorial process.8 Helicobacter pylori is classified as a group I carcinogen and is linked to gastric carcinoma in humans.9 In the present study, the prevalence of H. pylori in carcinoma of stomach was 70% with no significance difference in the prevalence of organisms between intestinal (69%) and diffuse (71%)type carcinoma. Our results concur with the histological studies from Europe10and Saudi Arabia11which reported the bacterial prevalence of 59% and 79.8% respectively;and in both studies no significant difference in the occurrence of H. pylori was found in both types of gastriccarcinoma. Where as in a similar retrospective study fromUnited States, the frequency of H. pylori in intestinal type gastric carcinoma was 89.2% compared with 31.8% indiffuse type gastric carcinoma.12 In the present study, the H.pylori prevalence in intestinal and diffuse type carcinoma  was significantly higher as compared to 24% in controls with normal gastric mucosa (P<0.001). This high yield was due to high prevalence of bacteria in patients with chronicgastritis and peptic ulcer disease in our population.13,14Various other important studies have used specific serumanti bodies against H. pylori, and two prospective case-control serological studies from Britain15and Hawaii 4 showed significant bacterial prevalence of 69% and 94% respectively in patients of gastric carcinoma. The overall prevalence of 70% in patients with gastric carcinoma in this study is comparable with the serological-based studies of H.pylori in patients with gastric carcinoma.4,15 Intestinal typeof gastric carcinoma is the predominant type in differentstudies10; in our study the intestinal type was 2.3 times more common than diffuse type (35:15). The advantage of selecting histological examination of gastric mucosa for the detection of H. pylori was to correlate its presence orabsence with the morphological changes of gastritis. The"gold standard" for H. pylori status is examination of at least two biopsies.16 In the present study 5.6 and 1.4 good-sized tissue blocks were taken from gastrectomy specimens of carcinoma cases. The number of biopsies was 2.4 and 2.2 incontrol cases of chronic gastritis and normal gastric mucosarespectively.  The mean age in this study was 49 years for patients with gastric carcinoma, which was a decade older than patients of chronic gastritis. In a study from Britain, the mean age at the time of diagnosis was 60 years (range 47-76 years).15The prevalence of H. pylori in the present study was 83 % (05 of 06 cases) in gastric patients under 30 years of  age, compared to 73% (11 of 15 cases) in controls with chronic gastritis. This suggests that the acquisition of H.pylori infection occurred earlier in life in gastric carcinomapatients. High rates of gastric cancer have been reported in areas in which H. pylori infection is common in early childhood.17 Gastric cancer occurs more frequently in males18.Male predominance was found in this study with afrequency of 60% in both types of carcinoma of stomachand there was no significant difference in the prevalence of H. pylori in either sex. Majority of intestinal type gastriccarcinoma were located in the gastric antrum, which is ingeneral agreement with western reports.19 In diffuse typecarcinoma the anatomical site showed no influence in theoccurrence of neoplasia. Similar result was observed byothers.20 The location of tumors does not affect thefrequency of H. pylori infection.12,13The association between H. pylori and chronicgastritis is well known.14-21 Helicobacter pylori associated chronic gastritis was the background lesion in majority ofthe intestinal and diffuse type of gastric carcinoma in thisstudy. The bacteria act directly via the release of enzymes ortoxins, or by the inflammatory response, which it provokes,and is thought to cause epithelial damage. Several studieshave suggested the role of H. pylori in gastriccarcinogenesis through stages of chronic gastritis tomucosal atrophy to intestinal metaplasia more so with intestinal type carcinoma.5,20However, a recent researchindicates that H. pylori infection is associated with DNAdamage in gastric epithelial cells, which could be a risk forgastric cancer in humans.22 Although mucosal atrophicchanges were present in significant number of intestinal and diffuse type of gastric cancer but there was no obviouscorrelation of mucosal atrophy and intestinal metaplasia with H. pylori in gastric carcinoma cases in the present study. In a report from Japan, no precursor lesions were found in the margins of microcarcinoma.23Hence, it was postulated that gastric atrophy and intestinal metaplasiaappear to be an indicator of long-standing proliferation, butare not necessarily specific precancerous lesions.24Strainvariation has impact on gastroduodenal diseases and it is shown that patients infected with H. pylori CagAstrains had increased rate of gastric epithelial cell proliferation.25

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