Cancer is a complex genetic disease. The vast majority of tumors are from joint effects of genetic factors and environmental factors. The formation and development of tumors is the result of accumulated changes of cytogenetics induced by carcinogens.
Somatic mutation is the specific mutation only in tumor cells and occurs in non-germline cells. Somatic mutations will not be passed on to future generations, whereas germline mutations are inherited from the parents, occur during embryonic formation, and exist in both normal tissue and tumor tissue.
Cancer genetic testing can help identify high cancer-risk populations, provide guidance for personalized medicine , predict chemotherapy drug efficacy, resistance and side-effects and screen patients for clinical trial enrollment.
The American Cancer Society (ACS) recommends that when the following conditions exist, you should consider genetic testing for cancer risk assessment:
1. Several first-degree relatives suffer from the same types of cancer (for example, mother/daughter/sister all suffer from breast cancer);
2. Cancers in family members are all associated with the mutation of the same gene (for example, breast cancer, ovarian cancer and pancreatic cancer patients are all BRCA2 mutated);
3. A family member was diagnosed with cancer at very young age;
4. A close relative suffers from a rare cancer, and that cancer is associated with inherited cancer syndromes;
5. Inherited cancer-related symptoms are found during medical examination (for example: many colon polyps);
6. One or more members of the family have a known genetic mutation.
This type of testing is suitable for all solid-tumor patients, including newly diagnosed patients, patients with disease progression or relapse, patients with drug resistance during treatment, patients with metastasis, and patients who need to find new treatment options because current drug treatment is ineffective.
Only a small percentage of patients respond satisfactorily to chemotherapy treatments. Pharmacogenetic and pharmacogenomic testing can predict efficacy and toxicity of chemotherapy and help develop personalized treatment plans for individual patients to improve clinical outcomes.
Mutation frequency refers to the ratio of copy numbers of mutated gene over the total copy numbers of both mutant gene and wild-type gene. Because there is no clear evidence that the mutation frequency has positive correlation with drug sensitivity, priority of medications listed in the report is based on genetic variations and clinical relevance, rather than mutation frequency.