Transcript عوامل مستعد كننده

Gastric Cancer
Remains the most common
malignancy in Japan and China .
It was the first-ranked malignancy
in the United States in the 1930s to
1940s, but it has rapidly declined
in more recent decades
Gastric neoplasms are predominantly
Malignant , and nearly 90 to 95 %
of cases are adenocarcinomas.
Less frequently observed malignancies
Include lymphomas, especially
non-Hodgkin’s lymphoma, as well as
sarcomas, such as leiomyosarcoma.
ADENOCARCINOMA OF THE STOMACH
Epidemiology:
There is great geographic variation in
the incidence of gastric cancer worldwide,
strongly indicating that environmental
factors influence the pathogenesis of
gastric carcinogenesis
Gastric adenocarcinoma localized to
the distal stomach has declined,
the incidence rate of proximal gastric,
gastro -esophageal adenocarcinomas
has been steadily increasing in the
United States
The incidence of gastric cancer
T
is variable
in different parts of
h
the word .
In japan 75 to 100 new cases
per 100,000 per year. other
areas of high prevalence
include chile and Scandinavia.
Epidemiologic studies of high-risk
populations have also suggested that
genotoxic agents such as N-nitroso
compounds may play a role in gastric
tumorigenesis. N-nitroso compounds
can be formed in the human stomach
by nitrosation of ingested nitrates,
which are common constituents of
the diet.
Etiology:
Risk factors for the development
of gastric adenocarcinoma can be
divided into environmental and
genetic factors as well as precursor
conditions
‫اتيولوژي كانسرمعده‬
‫‪ -1‬عوامل محيطي‬
‫‪ -2‬عامل ژنيتيك‬
‫‪ -3‬عوامل مستعد كننده‬
Typically, gastric cancer occurs
between ages 50 to 70 years and
is uncommon before age 30 years.
The rates are higher in males than
females by 2 to 1.
The achlorhydria associated
with gastritis related to
H. pylori,
pernicious anemia,
or other causes favors the growth
of bacteria capable of converting
nitrates to nitrites.
In united states is 7 cases per
100,000 per yr. It is the 10 th most
common cause of cancer in USA .
Increase in incidence of
adnocarcinoma of the distal
esophagus and cardia of the
stomach.
)‫(عوامل مستعد كننده‬
Patients with familial
adenomatous polyposis
also have a risk approximately
three time higher than that of
the general population of
developing gastric cancer.
)‫(عوامل مستعد كننده‬
Blood group antigens have also
been associated with gastric
cancer .
With the incidence highest in
persons with blood type A and
lowest in persons with blood
type O.
Etiology :
Dietary factor:
Salted Smoked fish
Pickled vegetables
Well-cooked meats
Fruit and fiber have been found to be
protective.
Vit C is thought to protect against some of the
mutagens present especially in smoked foods
)‫(عوامل مستعد كننده‬
Atrophic gastritis and gastric
cancer share a number of common
environmental risk factors.
It is likely that atrophic gastritis
and intestinal metaplasia represent
intermediary steps to gastric cancer.
)‫(عوامل مستعد كننده‬
.
Pernicious anemia
Peptic ulcer disease
Iron deficiency
N-nitroso compounds
H2 antagonists
)‫(عوامل مستعد كننده‬
Aspirin
Nonsteroidal antiinflamatory Drugs
have been associated with
a decreased risk of gastric cancer.
‫طرح پژوهشي شماره ‪1010‬‬
800
Cancer in Men
700
600
500
400
300
200
100
0
Skin
Lymphoma
Stomach
Colon
rectum
esophagus
blood
lung
bladder
prostst
800
700
‫نسبت وفور سرطان در زنان‬
600
500
400
300
200
100
0
skin
Stomach
Blood
esophagus
Breast
Lymphoma
Colon
rectum
Lung
Othrers