BACKGROUND
Colorectal cancer (CRC) is common in elderly patients. Mismatch repair (MMR) protein deletion is one of the causes of CRC. The
RAS
(
KRAS/NRAS
),
BRAF
, and
PIK3CA
genes are important gene targets in CRC treatment and are closely related to the prognosis and survival of patients. However, little is known regarding the relationship between the expression of MMR,
RAS, BRAF, PIK3CA
and the clinicopathological features in CRC patients.
AIM
To analyze the relationship between the expression of MMR,
RAS, BRAF, PIK3CA
and the clinicopathological features in CRC.
METHODS
A total of 327 elderly patients with CRC were enrolled, and immuno-histochemistry was used to detect the MMR protein. Real-time quantitative polymerase chain reaction was used to detect the
RAS
(
KRAS/NRAS
),
BRAF
, and
PIK3CA
genes. The clinicopathological data of the patients were recorded and analyzed by SPSS 19.0 statistical software.
RESULTS
In 327 elderly patients with CRC, the rate of MMR protein loss was 9.79% (32/327), and the deletion rate of four MMR proteins (MSH2, MSH6, MLH1, PMS2) was 1.83% (6/327), 3.06% (10/327), 7.65% (25/327), and 7.65% (25/327), respectively. There were no significant differences between MMR protein deletion and sex, pathological type, tumor morphology, differentiation degree or lymph node metastasis (
P
> 0.05), but there was a significant difference between MMR protein deletion and tumor diameter and tumor location (
P
= 0.048/
P
= 0.000). The mutation rates of the
KRAS, NRAS, BRAF
and
PIK3CA
genes in elderly CRC patients were 44.95% (147/327), 2.45% (8/327), 3.36% (11/327) and 2.75% (9/327), respectively; the
KRAS
gene mutation was closely related to tumor morphology (
P
= 0.002) but not to other clinicopathological features (
P
> 0.05), and there were no significant differences between
NRAS
gene mutation and clinicopathological features (
P
> 0.05). The
BRAF
gene mutation showed a significant difference in pathological type, tumor location, differentiation degree and lymph node metastasis (
P
< 0.05), but was not correlated with sex, tumor size and tumor morphology (
P
> 0.05). The
PIK3CA
gene mutation showed no significant differences in the above clinicopathological characteristics (
P
> 0.05). Significant differences were observed betwe...