Q1: What is cancer?
Cancer refers malignant tumors. It’s a general term for a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. The root cause of cancer can be attributed to the accumulation of DNA mutations, which leads to mass expression of proteins that promote cell growth, destruction of the function of tumor suppressor genes and cell cycle disorder.
Q2: What is hereditary tumor?
There are two major reasons for the ocurrence of tumor: acquired factors and congenital genetic factors. Tumor caused by congenital genetic factors is called hereditary tumor. All tumors are associated with genetic abnormalities. Hereditary tumors are caused by abnormal/defective genes carried by an individual. A gene that causes a hereditary tumor to occur after a defect occurs in it is called a tumor susceptibility gene. Through detection of hereditary tumor genes, we can learn whether the subjects carry hereditary tumor susceptibility genes with abnormal mutation to see if their genes are normal, and how much they are at risk for certain hereditary tumors. Detection of hereditary tumor genes can help to identify potential health risks and offer early warning before tumor occurs in an individual.
Q3: What is tumor driver gene?
Changes (mutations, amplification, rearrangement, etc.) in some important genes that regulate cell growth lead to the activation of proto-oncogenes and the inactivation of tumor suppressor genes. These changed genes that cuase normal cells to transform into tumor genes are called tumor driver genes. A certain type of cancer may be caused by different tumor driver genes. For example, in the case of non-small cell lung cancer, the common tumor driver genes are EGFR, ALK, HER2, MET, RET, ROS1, BRAF, KRAS and so on.
Q4: What is liquid biopsy?
Liquid biopsy is a new technique which uses high-throughput sequencing technology to detect small DNA fragments in blood. When a tumor cell dies, it releases into the blood a portion of its DNA, which carries genetic mutation information associated with the tumor. Unlike traditional biopsies, liquid biopsies remove the need for invasive surgeries and procedures by allowing medical professionals to test for signs of cancer from a simple blood-draw. We mainly detect two types of genes: one is domestically and internationally recognized genes that are related to tumor drug use; the other is genes that are closely related to the occurrence of tumors.
ctDNA refers to DNA fragments of tumor genome in human blood circulation system. It is a new type of highly sensitive and specific tumor marker that can be used to assess mutation of key genes of cancer. A large amount of researches indicate that result of detection of ctDNA in blood are 60% to 95% consistent with that of tissue detection.
Q5: What is targeted therapy and targeted drugs?
Targeted therapy usually refers to molecularly targeted therapy or targeted cancer treatment, i.e. the use of drugs or other substances to inhibit the molecular targets involved in the growth, proliferation and migration of cancer cells. Targeted therapy targets specific molecules associated with cancer, most agents for targeted therapy are biopharmaceuticals.
Targeted drugs are designed to target genetic mutations that cause cancer, which can only act on patients carrying targeted genetic mutations that are specific to a targeted drug. For patients with different types of cancer, corresponding molecular detection may be carried out to see if genetic mutations needing targeted drug therapy have occurred in them. Targeted drugs are not effective for everyone, and only patients with specific genetic mutations have better treatment outcomes. Therefore, targeted drugs must be used under the guidance of a professional doctor. Without genetic testing, blind use of targeted drugs can lead to increase of patients’ financial burden and missed optimal treatment time.
Q6: Why does drug resistance occur afetr patients taking targeted drugs? How to deal with drug resistance?
Molecularly targeted drugs are used to inhibit the growth of tumor cells and eventually kill them to achieve therapeutic goals. Specific molecularly targeted drugs work on one protein or one molecule of a certain type of cancer cells, inhibiting only one pathway of tumor growth. When a pathway is inhibited, the tumor cells constantly select other pathways to synthesize the materials needed for their growth and thus develop resistance.
The underlying cause of drug resistance of tumor is change in genetic mutation of the tumor. The tumor area that was targeted for treatment decreased, the tumor area that was not treated increased, and then new type of genetic mutation was developed. The best way to deal with drug resistance of tumor is to get tested again.
Q7: Genetic testing means testing a lot of genes?
Genes carry all the genetic information of the human body, and their chemical nature is DNA, or deoxyribonucleotide. When some genes appear abnormal, they can affect the physiological activities of the human body, which can lead to disease. Genetic mutation is the root cause of cancer.
The occurence of many type of cancers is controlled by more than a single gene. For example, the pathogenesis of non-small cell lung cancer is affected by a series of driver genes. Different targeted drugs have been developed for each type of mutation and are gradually being used in clinical treatment. Common targets include EGFR, eml4-alk, BRAF, KRAS, PIK3CA, MET, ROS1, etc.
The purpose of genetic testing is to help patients search for targeted drugs. Some types of genetic mutations are common, many types of mutations occur only in a small number of people. But as long as they can be detected, it means appropriate medication can be applied to the treatment of cancer patients. Comprehensive genetic testing may provide therapeutic potential for cancer treatment with targeted drugs that are still in clinical trials.