CLINICOPATHOLOGICAL FEATURES AND MICROSATELLITE INSTABILITY STATUS OF GASTRIC CARCINOMA IN THE UNIVERSITY COLLEGE HOSPITAL, IBADAN – A TWELVE-YEAR RETROSPECTIVE STUDY

Abstract

Background & Aims: The most recent study on the clinicopathological features of gastric
carcinoma from the University College Hospital (UCH), Ibadan, was done in 2000. The aims of
this study were to (i) update the knowledge on the clinicopathological features of gastric
carcinoma diagnosed in the Pathology Department of the UCH Ibadan between 2000 and 2011
(ii) define the rate of MSI in gastric carcinoma (iii) compare the clinicopathological features of
MSI and MSS tumours.
Materials & Methods: The clinical and demographic data and histological diagnoses of
patients diagnosed between 2000 and 2011 were retrieved from the UCH Cancer Registry, the
Pathology Department records and from the UCH Medical Records. Also, slides were made from
archival samples of the same patients and reviewed to confirm the histological diagnoses,
subtype the tumour and determine the presence/ absence of other clinicopathological parameters.
MSI was assessed on 47 archival samples (formalin-fixed, paraffin-embedded gastric carcinoma
tissue samples) using High Resolution Melt Curve Analysis on BAT 25 and BAT 26
microsatellite loci. Statistical analyses were done using SPSS version 19.
Results: A total of 117 cases of gastric carcinoma were histologically diagnosed at the Pathology
Department of UCH, Ibadan, between 2000 and 2011 giving a relative frequency ratio of 1.38%.
This represented 18.4% (118 out of 636) of all gastrointestinal tract malignancies diagnosed in
the same period. There was a male preponderance with male:female ratio of 1.72:1. The middle
age and elderly make up about 76.1%. The modal age group was 51-60 years; mean age was
53.36+ 15.31 years. The disease was clinically and histologically advanced in 92.8% of cases.
Gastric tumours were predominantly antral/pyloric in 60 out of 75 cases (80%), exophytic in 32
out of 53 cases (62.3%), and intestinal histotype in 55 out of 117 cases (46.5%); although a rise
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in the diffuse histological type was observed. The exophytic and ulcero-infiltrative tumours were
more significantly associated with intestinal type than the flat/diffusely infiltrating. Also, the
female gender was significantly associated with the less differentiated tumours than the male
gender. MSI was found in 12 out of the 47 cases (25.5%) of gastric carcinomas tested in this
study. However, there was no significant association between the microsatellite status and the
clinicopathological features of gastric carcinoma.
Conclusions: The relative frequency ratio of gastric carcinoma in Ibadan between 2000 and
2011 is lower than results from previous studies done in this centre. There is a fall in the rate of
the intestinal type of gastric carcinoma relative to the diffuse type compared to a previous study
from our centre. About a quarter of gastric carcinoma from our cohort is MSI-positive, although
no association was found between the microsatellite status of the tumours and the
clinicopathological features, probably due to the small sample size used in this study. The
implication of this finding is that DNA mismatch repair defect is a pathogenetic mechanism of
gastric carcinoma in a significant proportion of our patients. Lastly due the mismatch repair
defect this proportion of our gastric carcinoma patients may show poor response to cisplatin
based chemotherapy.

CLINICOPATHOLOGICAL FEATURES AND MICROSATELLITE INSTABILITY STATUS OF GASTRIC CARCINOMA IN THE UNIVERSITY COLLEGE HOSPITAL, IBADAN – A TWELVE-YEAR RETROSPECTIVE STUDY