Why is genetic testing so important for colorectal cancer?

Why is genetic testing so important for colorectal cancer? What role does genetic testing play in colorectal cancer?

Colorectal cancer has become top 5 in cancer incidence and mortality in many countries. It poses a serious threat to the health of the people. As the understanding of cancer continues to deepen, the notion that cancer is related to mutations in related genes has become popular. As a result, genetic testing for cancer has become more and more popular. What role does genetic testing play in colorectal cancer? Let’s find out together.

01 Causes of colorectal cancer

Many cancers are often the result of multiple factors at the same time, and colorectal cancer is no exception. The pathogenesis of colorectal cancer has the following points:

Dietary factors

High fat, high protein, low dietary fiber intake; vitamin deficiency; intestinal flora imbalance; intake of nitrite compounds;

Family genetic factors

Some genetic diseases include Lynch syndrome, familial adenomatous polyposis, juvenile polyposis syndrome, sawtooth polyposis syndrome, pigmented polyp syndrome, Lee-Fumeni syndrome and Cowden syndrome, MUTYH association Polyposis can also cause colorectal cancer.

Some family genetic factors that cause colorectal cancer can generally be found through genetic testing.

02  Why do genetic testing for colorectal cancer?

Genetic testing is of great significance for colorectal cancer and people at risk of colorectal cancer:

Contribute to the diagnosis of the disease

Colorectal cancer can have no symptoms in the early stage, and timely genetic testing can detect it in the early stage of the disease and intervene. At present, the detection of genetic markers for cancer is regarded as the most effective early warning method.

Prompt the patient’s prognosis

For colorectal cancer, some patients have a good prognosis and some patients have a poor prognosis. This difference is also related to genes. For example: BRAF mutant colorectal cancer has a high degree of malignancy, a high rate of lymph node metastasis and a high incidence of locally advanced stages; patients with highly unstable microsatellites (MSI-H) have a relatively good prognosis.

Contribute to the screening of risk groups

A part of the colorectal is genetically caused, the most typical example is Lynch syndrome. Lynch syndrome is also known as hereditary non-polyposis colorectal cancer. People with Lynch syndrome have a 70%-80% risk of colorectal cancer. Lynch syndrome can be detected by detecting the MMR gene (that is, mismatch repair gene), so that relevant risk groups can take preventive measures in time.

Able to choose a more appropriate treatment plan

With the same medicine, the effect on patients with mutations in some genes becomes unsatisfactory. This is also a major reason for genetic testing. Drugs for cancer are becoming more and more precise, and genetic testing allows doctors to choose the most suitable drugs for patients

03 What are the differences in treatment and medication for colorectal cancer patients with different gene mutations?

Some gene mutations are very important for the selection of drugs, especially chemotherapeutics and targeted drugs, such as:

(1) There are no mutations in the three genes of KRAS, NRAS and BRAF, and chemotherapy drugs such as 5-FU (pentafluorouracil) can work. For patients with stage II colorectal cancer with highly unstable microsatellites, 5 -FU can hardly work;

(2) For patients with colorectal cancer with NTRK fusion, TRK inhibitors such as larotinib and entricinib can be used;

(3) It is the KRAS and NRAS mentioned above. Patients without mutations can use cetuximab or panitumumab. For patients with mutations, the application of cetuximab may even have a negative impact on the overall efficacy.

04 What genes need to be tested for colorectal cancer patients?

Generally, patients should first check mismatch repair protein (MMR) and microsatellite stability (MSI). Patients with metastatic or recurrent colorectal cancer who need chemotherapy are recommended to do RAS, KRAS, NRAS and BRAF gene tests. In addition, , HER2 and NTRK inspections also play a certain role in finding effective drugs.

05 Who needs genetic testing for colorectal cancer?

For suspected hereditary colorectal cancer, hereditary non-polyposis colorectal cancer (HNPCC), familial adenomatous polyposis (FAP), attenuated FAP (AFAP), PJS syndrome, juvenile polyp syndrome (JPS) Patients with PTEN hamartoma syndrome and high-risk groups are recommended to carry out related gene testing to determine whether they carry related gene mutations, so as to achieve early detection, early prevention, and early intervention to reduce morbidity and mortality.

(source:internet, reference only)

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