Content Guide

Tumor is a genetic disease. When one ormore genes in a cell are mutated, it may cause tumors.Tumors are verydifferent, even if it is a tumor at the same site, the gene mutation site and thetypes of the primary tumor are not the same.

"Love andhatred" of Gene Mutation and Tumor

If the tumor has metastasized, the genemutation information of the original tumor and the metastatic tumor may also bedifferent. In addition, under the influence of environmental factors such asdrugs, immune system, and internal competitive pressure, the gene mutations oftumors will randomly undergo multiple mutations. With the deepening of geneticand molecular research, more and more tumor cell signaling pathways have beendiscovered. A large number of clinical studies have shown that theamplification/mutation/expression status of specific genes in the pathway isclosely related to the effectiveness of targeting and chemotherapeutic drugs.

Therefore, clinically detecting theamplification/mutation/expression of specific genes in these pathways cantailor a set of the most suitable treatment plan for each patient, therebymaximizing the effectiveness of treatment and reducing toxic side effects ofdrugs, preventing improper medication and delayed treatments.

Clinical TumorApplication of Genetic Testing

At present, the main clinical applicationsof genetic testing in tumors are as follows:

1) Tumor Susceptible gene testing.The occurrence and development of tumors are closely related to heredity. Manygene mutations are inherited in the family. People who carry these mutationshave a higher risk of developing tumors. Genetic testing can predict the riskof corresponding tumors and be used to carry out active health management.

2) Liquid biopsy technology is oneof the tumor screening technologies, which is a method used to achieve earlycancer screening through the sequencing of free DNA. At present, genetictesting is more mature in cancer recurrence screening.

3)The tumor target therapy is atreatment that through the comparison of the patient's tumor tissue DNA andwhole blood DNA, to detect potential gene mutations, and select suitabletargeted therapies that can benefit the patients under current clinicalguidelines.

4) Genetic testing can also be usedfor the detection of tumor invasion and metastasis. Through genetic testing ofmetastases and in situ, it is possible to detect key tumor driving genes andselect suitable target treatments.

The "past andpresent" of family hereditary tumors

Sporadic tumors are polygenic diseases,which are caused by the interaction of multiple genes with different functionsand induced by complex carcinogenic conditions. The complex pathogenesis poseschallenges to the prevention, diagnosis and treatments of tumors.

“Hereditary tumorsare transmitted in families, with 5% to 10% of total tumors patients. Althoughsome tumors are multifactorial, their occurrence and development are caused byinherent gene mutations, which can be traced in the patient's family.”

From Genetic counseling for hereditary tumors, PekingUniversity Medical Press, June 2021 V1 Edition

Among the malignant tumors, colorectalcancer, breast cancer, ovarian cancer and other cancers have a higherproportion that will show familial disease characteristics. Statistics showthat about 5-10% of breast cancer patients and about 10-15% of ovarian cancerpatients are inherited familial diseases. Carriers of BRCA1 and BRCA2 genemutations have a lifetime risk of developing breast cancer at 80% and 45%, andthe risk of ovarian cancer is 54% and 11%.

Hereditary non-polyposis colorectal cancer(HNPCC, also known as Lynch syndrome), is a common hereditary susceptibilitysyndrome of colorectal cancer. HNPCC is mainly caused by germ cell mutations inthe mismatch repair genes MLH1, MSH2, MSH6 and PMS2. Although advancedmalignant tumors are difficult to cure, tumors are indeed preventable, thegenetic information is a critical step.

The 2021 version of the "Recommendationsfor the Screening and Prevention of Common Malignant Tumors for Residents"focuses on the information of prevention and screening of hereditary tumors,especially common hereditary colorectal cancer, colorectal cancer, hereditarybreast cancer and ovarian cancer syndrome.

Highrisk people for hereditary tumors:

1. People with family history.

2. Those who have family relatives with a low age of canceronset.

3. People who have several different types of cancer.

4. Family cancer is manifested in a pair of organs, such ascancer on both kidneys or breasts.

5. Several first-degree relatives (parents, siblings, orchildren) have the same cancer (such as mother, daughter, sisters sufferingfrom breast cancer); family members suffering from breast or ovarian cancer;family members suffering colorectal cancer and endometrial cancer.

6. People who have an unusual type ofcancer in the family (e.g., male breast cancer).

7. People with birth defects known to be related tohereditary cancer syndromes in the family, such as certain benign skin growthand bone abnormalities related to neurofibromatosis type I;

8. As a family member known to have an increased risk of acertain hereditary cancer susceptibility syndrome, and at the same time haveone or more of the above characteristics.

9. Many family members have cancer

10. Carrying currently known genetic mutations and symptomsof cancer 

The aboveinformation is  from 2021 editionof "Recommendations for the Screening and Prevention of Common MalignantTumors in Residents" Shanghai Anti-Cancer Association