Introduction
Helicobacter pylori (H. pylori) infection has been recognized as a major pathogen of gastric cancer [1]
[2]. Correspondingly, several reports have indicated that H. pylori eradication therapy mediates a preventive effect against gastric cancer development
[3]
[4]
[5]
[6]. However, gastric cancer was still found to persist in some cases. Therefore, a
more simple and straightforward observation method is necessary to monitor gastric
cancer following H. pylori eradication.
Histological gastric atrophy and intestinal metaplasia (IM) are regarded as precancerous
lesions, and are recognized as risk factors both before and after H. pylori eradication [2]
[7]. Endoscopic atrophy classification (EAC) according to Kimura and Takemoto [8] has frequently been used to evaluate the atrophic degree of gastric mucosa. Moreover,
the degree of EAC has been found to correlate with the degree of histological atrophy
[8]
[9]. However, these studies do not mention the correlation between EAC and atrophy and
IM after eradication. In addition, EAC is associated with the incidence of gastric
cancer after eradication [10], and provides a noninvasive method for predicting gastric cancer after eradication
compared with biopsy of gastric mucosa [10]
[11].
While H. pylori eradication has been shown to reduce the degree of gastric atrophy and IM [12]
[13]
[14]
[15], the correlation between EAC and post-H. pylori eradicated gastric mucosa and, in particular, atrophy and IM status has not been
investigated yet. Therefore, in this study, the relationship between EAC and histological
gastric atrophy and IM not only before but also after H. pylori eradication was examined in order to evaluate the usefulness of EAC for detecting
the risk of gastric cancer following H. pylori eradication.
Patients and Methods
A total of 325 patients who underwent upper gastrointestinal endoscopy and had examination
for detection of H. pylori at Oita University Hospital between January 1995 and December 2010 were enrolled
in this study. The patients with H. pylori infection subsequently underwent H. pylori eradication. These subjects were examined repeatedly with endoscopy more than 3 years
after H. pylori eradication in order to survey gastric mucosal alteration after eradication. All study
protocols were approved by an institutional review board. To detect H. pylori, patients underwent at least one of the following assays: a rapid urease test (RUT),
histology, culture testing, and/or a urea breath test (UBT). A subset of patients
underwent all of the assays. Only histology and culture tests were used for H. pylori diagnosis until RUT and UBT were developed.
After confirming the safety of eradication therapy and obtaining further informed
consent, patients with H. pylori were administered a proton pump inhibitor-based combination therapy. Briefly, between
4 weeks and 6 months after completing eradication therapy, RUT, histology, cultures,
and/or UBT examinations were repeated. H. pylori eradication was considered successful if all tests were negative. H. pylori-negative cases and cases involving H. pylori recrudescence or reinfection were excluded. Endoscopies were also repeated for patients
who underwent successful H. pylori eradication. The endoscopic findings performed 78.05 ± 36.72 (range 36 – 153) months
after eradication were evaluated for this study.
Endoscopic evaluation
The endoscopic examinations were performed using an Olympus electroscope (model Q-240,
260, HQ-260, and others; Tokyo, Japan). Endoscopic atrophy was defined using an endoscopic-atrophic-border
scale previously reported by Kimura and Takemoto [8]. This scale correlates with histological results [8]
[9] and includes the following classifications: 1) close-type, when the atrophic border
remains on the lesser curvature of the stomach; and 2) open-type, when the atrophic
border extends along the anterior and posterior walls of the stomach and is not associated
with the lesser curvature of the stomach. Close-type and open-type atrophy were further
classified as none (C0), mild (C1, 2), moderate (C3, O1), and severe (O2, 3) atrophy
([Fig. 1]). In this study, atrophy grade were also scored as C0: 0, C1: 1, C2: 2, C3: 3, O1:
4, O2: 5, and O3: 6 respectively, with 0 representing an absence of atrophy and 6
indicating severe atrophy.
Fig. 1 Extension of atrophic border of Kimura-Takemoto classification [8]. The atrophy range was shown with light gray.
Histological evaluation
Biopsies were performed prior to eradication in order to diagnose H. pylori. Biopsy specimens were obtained from the greater curvature of the antrum and the
greater curvature of the corpus, which are two of five points recommended by updated
Sydney system [16]. Gastric mucosa samples were subsequently evaluated according to updated Sydney
system with the degree of inflammation, neutrophil activity, atrophy, and IM classified
as: 0, ‘normal’; 1, ‘mild’; 2, ‘moderate’; and 3, ‘marked’. Grade of histological
gastritis was evaluated with this score 0, 1, 2, and 3. Histological evaluations were
performed by two experienced pathologists from Oita University Hospital. Correlations
between endoscopic atrophy classification scores and histological atrophic scores
were evaluated before and after H. pylori eradication.
Statistical analysis
Statistical analyses were performed using SPSS software (PASW Statistics 18, SPSS
Japan), and data are expressed as the mean ± standard deviation. Student’s t-test was performed to compare updated Sydney system scores before and after eradication.
The Mantel-Haenszel test for trend was used to compare endoscopic atrophic degree,
histological gastric atrophy, and IM. P-values less than 0.05 were considered significant.
Results
Disease history
Of 325 subjects, those who were H. pylori-negative or had unsuccessful eradication or recurrence of H. pylori infection were excluded ([Fig. 2]). Forty-three cases were lost during observation. A total of 230 patients (137 males,
93 females) were analyzed. The mean age of this cohort at the time of eradication
was 58.0 ± 11.8 y. The cohort was also characterized by a history of chronic gastritis
(n = 105), gastric ulcers (n = 54), duodenal ulcers (n = 45), gastroduodenal ulcers
(n = 13), gastric cancer (n = 7), gastric adenoma (n = 1), and mucosal-associated
lymphoid tissue lymphoma (n = 5).
Fig. 2 Follow-up flowchart of patients
Endoscopic gastric atrophy
Prior to H. pylori eradication, the endoscopic atrophic grades assigned to the cohort included: C1 (n = 22),
C2 (n = 47), C3 (n = 41), O1 (n = 61), O2 (n = 36), and O3 (n = 23). After eradication,
endoscopic findings that were performed 78.05 ± 36.72 (range 36 – 153) months after
eradication were evaluated. The results of endoscopic examination at the beginning
and the end of the observation period were assessed. The endoscopic grades were C1
(n = 20), C2 (n = 58), C3 (n = 59), O1 (n = 50), O2 (n = 31), and O3 (n = 12). Compared
with the grades assigned before eradication, an improvement in endoscopic grade was
observed following successful eradication in 94 cases, while no change or exacerbation
of atrophy was observed in 78 cases and 58 cases, respectively. The mean endoscopic
gastric atrophy score for all of the cases was 3.46 ± 1.43 before eradication and
significantly reduced to 3.20 ± 1.33 after eradication (P = 0.026).
Histological atrophy and IM
The mean atrophy scores before and after eradication for all of the cases were: 1.45 ± 0.05
and 0.92 ± 0.05 at the antrum (P < 0.001) and 0.50 ± 0.05 and 0.07 ± 0.02 at the corpus (P < 0.001), respectively in each case. The mean IM scores before and after eradication
were 0.55 ± 0.06 and 0.47 ± 0.05 at the antrum (P = 0.154) and 0.09 ± 0.02 and 0.05 ± 0.02 at the corpus (P = 0.096), respectively in each case. Atrophy scores at both the antrum and the corpus
showed significant improvement following eradication. However, IM scores showed no
significant change at either site.
Comparison of endoscopic and histological findings
[Fig. 3] presents the endoscopic and histological atrophy and IM before and after eradication.
Seven years after successful eradication, EAC improved from O2 ([Fig. 3 a, b]) to C3 ([Fig. 3 c, d]). Histological atrophy also improved 2 to 0 after eradication at both the antrum
([Fig. 3 f, h]) and the corpus ([Fig. 3 e, g ]). Similarly, the IM score at the antrum improved from 2 to 0 ([Fig. 3 f, h]). [Fig. 4] presents another case. Seven years after successful eradication, this case did not
show improvement in EAC, with scores of O2 ( [Fig. 4 a, b]) to O2 ([Fig. 4 c, d]). However, histological atrophy improved from 2 to 0 after eradication at both the
antrum ([Fig. 4 f, h]) and corpus ([Fig. 4 e, g]). The IM score at the antrum also improved from 1 to 0 ([Fig. 4 f, h]).
Fig. 3 Relationship between endoscopic and histological findings. Endoscopic findings before (a, b) and 7 years after eradication (c, d) (white arrows: atrophic border) showed atrophy improvement. Histological findings
at the corpus (e) and antrum (f) before eradication showed improvement at the corpus (g) and antrum (h) after eradication.
Fig. 4 Relationship between endoscopic and histological findings. Another case of endoscopic
findings before eradication (a, b) and 7 years after eradication (c, d) (white arrows: atrophic border) showed no improvement. Histological findings at
the corpus (e) and antrum (f) before eradication improved at the corpus (g) and antrum (h) after eradication.
Comparison of endoscopic and histological atrophy and IM scores
At the antrum, the histological atrophy scores before and after eradication for each
endoscopic grade were: C1: 1.05 and 0.74 (P = 0.104); C2: 1.32 and 0.90 (P = 0.004); C3: 1.40 and 0.91 (P = 0.003); O1: 1.56 and 1.05 (P < 0.001); O2: 1.53 and 0.92 (P = 0.003); O3: 1.63 and 1.20 (P = 0.059), respectively ([Fig. 5 a]). Atrophy scores, except C1 and O3, showed significant reductions following eradication.
At the corpus, the histological atrophy scores before and after eradication for each
endoscopic grade were: C1: 0.26 and 0.00 (P = 0.028); C2: 0.28 and 0.02 (P = 0.003); C3: 0.51 and 0.04 (P < 0.001); O1: 0.56 and 0.11 (P < 0.001); O2: 0.70 and 0.04 (P < 0.001); O3: 0.74 and 0.50 (P = 0.29), respectively ([Fig. 5 b]). Atrophy scores, except for O3, showed significant reductions following eradication.
Fig. 5 Relationship between endoscopic atrophy scores and histological atrophy scores before
and after H. pylori eradication. Each degree of endoscopic atrophy showed significant improvement of
histological atrophy following eradication, except for C1 and O3 at the antrum, and
O3 at the corpus. Endoscopic atrophy classification showed significant correlation
with histological atrophy except antral site after eradication.
The P-value for the Mantel-Haenszel test for trend was 0.008 before eradication and 0.069
after eradication at the antrum, and was 0.004 before eradication and 0.031 after
eradication at the corpus. The trend in EAC and histological atrophy was significant
before eradication and after eradication, except at the antrum after eradication ([Fig. 5 a, b]). At the antrum, the histological IM scores before and after eradication for each
endoscopic grade were: C1: 0.21and 0.21 (P = 0.50); C2: 0.31and 0.26 (P = 0.35); C3: 0.72 and 0.47 (P = 0.11); O1: 0.56 and 0.59 (P = 0.43); O2: 0.73 and 0.69 (P = 0.45); O3: 0.90 and 1.10 (P = 0.32), respectively ([Fig. 6 a]). At the corpus, the histological IM scores before and after eradication for each
endoscopic grade were: C1: 0.00 and 0.05 (P = 0.17); C2: 0.02 and 0.00 (P = 0.16); C3: 0.08 and 0.00 (P = 0.092); O1: 0.09 and 0.06 (P = 0.38); O2: 0.18 and 0.08 (P = 0.18), O3: 0.26 and 0.50 (P = 0.27), respectively ([Fig. 6 b]). None of the IM scores after eradication for any of EAC levels exhibited any significant
improvement at both the antrum and the corpus. The P-value for the Mantel-Haenszel test for trend was 0.005 before eradication and < 0.0001
after eradication at the antrum, and 0.048 before eradication and 0.027 after eradication
at the corpus. EAC and histological IM showed a significant trend both before and
after eradication ([Fig. 6 a, b]).
Fig. 6 Relationship between endoscopic atrophy scores and histological IM scores before and
after H. pylori eradication.Each degree of endoscopic atrophy showed no significant improvement of
IM after eradication. Endoscopic atrophy classification showed significant correlation
with histological IM at both sites before and after eradication.
Discussion
Although H. pylori eradication has the potential to prevent gastric cancer, recurrence of gastric cancer
has been observed following H. pylori eradication [4]
[5]
[6]
[17]
[18]. Therefore, the incidence of gastric cancer recurrence after H. pylori eradication remains to be fully characterized. Although molecular factors predictive
of gastric cancer are useful [19]
[20], simpler methods are believed to be desirable. Atrophy and IM have been recognized
as risk factors for gastric cancer following H. pylori eradication [10]
[11]
[21]
[22]
[23]. Intestinal-type gastric cancer, appears to undergo a multistep carcinogenic process,
from atrophic gastritis to IM to dysplasia [7]. To identify high-risk factors for cases of gastric cancer that develop after H. pylori eradication, a minimally invasive method, such as endoscopic findings without biopsy,
is needed. In general, annual endoscopy has been reported to be useful in detecting
most new tumors, and is associated with improved rates of survival [24]. Therefore, endoscopic surveillance after eradication is considered to be very important.
Current results cannot identify the surveillance period that is optimal in each individual
case. Further examination is necessary to identify the optimal surveillance period
for low-risk and high-risk patients. The use of specific wavelengths of light, such
as magnifying narrow-band imaging [25]
[26]
[27] for performing endoscopies has been used recently. Currently, this method is very
useful for gastric cancer surveillance. However, we hypothesize that a more basic
and cost-effective observation method may help evaluate gastric cancer development
following H. pylori eradication. In the current study, a significant correlation between EAC and histological
atrophy before eradication was identified, and this result is consistent with that
of previous reports [8]
[9]
[28]. However, to our knowledge, this is the first study to identify a correlation between
EAC and histological atrophy both before and after H. pylori eradication. Patients with severe endoscopic atrophy have a high risk of gastric cancer
after eradication [10]
[22]
[23], and our previous study indicated that patients who develop gastric cancer after
eradication exhibit severe endoscopic atrophy and histological antral atrophy compared
with patients without gastric cancer [11]. Furthermore, a more severe grade of IM has been observed in gastric cancer cases
following eradication [23]. Therefore, it has been hypothesized that EAC is valid to judge gastric cancer risk
before H. pylori eradication. Although the endoscopic index of successful eradication was evaluated
[29], EAC and histological IM have not been compared over a long period of time following
eradication. In the current study, EAC and histological atrophy were significantly
correlated at the corpus. In addition, almost every degree of endoscopic atrophy that
was observed in the current cohort following eradication was accompanied by a significantly
low level of histological atrophy compared with levels prior to eradication. These
results suggest that there is less improvement in endoscopic atrophy than in histological
atrophy following eradication. In [Fig. 4], histological atrophy and IM are shown to be improved after eradication, while an
improvement in endoscopic atrophy was not observed. Thus, the degree of histological
atrophy after eradication was milder than that observed before eradication for a similar
endoscopic atrophy range.
There was also no significant relation between EAC and histological atrophy at the
antrum following eradication. This result is attributed to the observation that severe
histological atrophy was remarkably improved following eradication. However, histological
IM exhibited a significant correlation with endoscopic atrophy degree at the antrum
both before and after eradication. Therefore, as the degree of endoscopic atrophy
becomes more extensive, histological IM at the antrum also becomes more extensive,
even after H. pylori eradication. Moderate-to-severe endoscopic atrophy has been reported to exhibit extensive
incomplete IM [30], which is consistent with the IM distribution observed in the current study. Unlike
histological atrophy, no significant difference in the degree of histological IM was
observed before and after eradication. Many studies have indicated that the gastric
mucosa undergoes alterations following H. pylori eradication [12]
[13]
[14]
[15]. However, in two recent meta-analyses, improvement in atrophic gastritis, but not
in IM, was observed following H. pylori eradication [13]
[14]. In our previous study, histological atrophy was found to improve, however, IM only
improved at the lesser curvature of the corpus following eradication [15]. In the current study, no significant alterations in IM before and after eradication
were observed, consistent with results of these previous studies. Because the long
observation period may have influenced the results of this study, further study of
cases involving surveillance during a narrower time period may be necessary.
Regarding the strong correlation between EAC and histological IM, it has been suggested
that EAC is a useful index for long-term gastric cancer risk following H. pylori eradication. In general, IM does not improve following eradication, neither does dysregulation
of micro-RNAs in IM [31]. Taken together, these results suggest that IM should be regarded as one of the
most informative factors predictvie of gastric cancer following H. pylori eradication. Furthermore, because gastric cancer tends to develop more frequently
at the antrum than at the corpus following H. pylori eradication [23], the strong association between EAC and histological IM at the antrum may indicate
that EAC may not depend on whether screening for gastric cancer is performed before
or after H. pylori eradication. In conclusion, EAC exhibited a significant correlation with histological
atrophy and IM at the antrum and corpus in the gastric mucosa before and after H. pylori eradication, except for antral atrophy after eradication. Thus, EAC may be useful
for observations of histological atrophy and IM degree independent of invasive biopsies,
and it may also be beneficial for evaluating the risk of gastric cancer after H. pylori eradication.
