Table 2 . Summary of evidence about the association between genetic factors and ESCC .
| Genetic factors | Location | Tumor abnormality | Risk factors may be associated with gene expression | Study Type/method (reference) | Association and Risk )Reference) | ||
| other regions | Golestan | other regions | Golestan | ||||
| EGFR | 17p13 |
-Oncogene -Amplification/ overexpression |
-Benzopyrenediol
epoxide
(BPDE), a
carcinogen present
in tobacco
&environmental
pollution - bile acid (a tumor promoter in gastrointestinal cancer) |
Systematic review/ metaanalysis | Direct sequencing |
In EGFR overexpression: -positive in 722 of 1, 150 - higher depth of invasion - vascular invasion - poor prognosis 65 |
- EGFR mutations:
rare in high
incidence areas -Rare activating mutations (2.6%), frequent EGFR protein over-expression (65%) 66 |
| Cyclin D1 | 11q13 |
-Oncogene -Amplification |
-------------- | Immunohistochemistry 108 | --------------- |
In cyclin D1
positive tumors: -prevalence: 86.7% - adventitia invasion: 88.2% -lymph node metastasis :87.5% -poorly differentiated :92.9% 108 |
-------------- |
| P53 | 17p13 |
Tumor
suppressor
genes: Point mutation; LOH |
-Environmental
carcinogens
(PAH) -Temperature and composition of tea -Cigarette smoking |
PCR and DNA sequencing71 | Immunohistochemical staining 73,76,109,110 | - p53 gene mutations in 56.5% tumors 71 |
-TP53 mutations in
89.9% of ESCC73 -P53protein overexpression in 74.2% of ESCC cases76 - one or more p53gene point mutations in 65% 109 - Positive expression of p53 protein in 56.2% of ESCC cases 110 |
| P21 | 6p21.2 | Tumor suppressor | Cigarette smoking | Immunohistochemical |
-Case control75 -Immunohistochemical staining110 |
-The incidences of grade 3 were 67% and 20% in the cases with a positive and negative p21 expression, respectively (p=0.0213) 111 |
-None of the p21
genotypes were
significantly associated
with risk of
ESCC
(p=0.52, OR=1.24,
95% CI: 0.63-
2.42) 75 -p21 overexpression was associated with poorer clinical outcome in ESCC (p= 0.009) 110 |