Genomic testing for cancer involves analyzing the complete set of DNA within cancer cells to identify specific changes or mutations. This approach is becoming increasingly important in modern cancer care, offering a detailed understanding of a tumor’s biological characteristics. By examining the cancer cell’s unique genetic blueprint, doctors can gain insights into how a tumor might behave and respond to different treatments. This advanced testing method helps to personalize treatment strategies for individual patients.
Understanding Genomic Testing
Genomic testing analyzes the entire genetic makeup of a cancer cell, rather than just a few individual genes. This comprehensive analysis helps pinpoint the specific DNA alterations that drive tumor growth and development. Cancer is fundamentally a disease of the genome, arising from DNA changes that lead to uncontrolled cell growth. Understanding these changes provides a detailed molecular profile of the tumor.
It is important to distinguish genomic testing from genetic testing. Genetic testing typically looks for inherited changes in a person’s germline DNA, often to assess cancer risk that can be passed down through families. In contrast, genomic testing for cancer specifically examines the DNA of tumor cells, identifying acquired changes unique to the cancer. These acquired changes, known as somatic mutations, guide cancer treatment.
The Process of Genomic Testing
The process typically begins with obtaining a sample from the patient’s cancer, often through a biopsy or surgery. For some patients, when a tissue biopsy is difficult or not possible, a blood sample can be used for a “liquid biopsy.” Liquid biopsies detect circulating tumor DNA (ctDNA) shed by cancer cells into the bloodstream, offering a less invasive method for analysis.
Once collected, DNA is extracted from the cancer cells and analyzed using advanced sequencing technologies, such as next-generation sequencing. These technologies read millions of DNA fragments simultaneously, identifying alterations like point mutations, insertions, deletions, and gene fusions. The data is then processed by specialized computer programs and interpreted by a team of experts, including molecular pathologists and oncologists, to identify relevant genetic changes that influence treatment decisions.
Genomic Insights for Cancer Treatment
Information from genomic testing helps personalize cancer treatment, a practice known as precision medicine. Identifying specific genomic alterations in a tumor guides the selection of targeted therapies. These drugs attack cancer cells based on their genetic changes, often resulting in fewer side effects compared to traditional chemotherapy. For example, mutations in genes like EGFR, BRAF, or ALK can indicate a patient’s cancer might respond well to particular targeted drugs.
Genomic testing also helps predict how a patient might respond to various treatments, including chemotherapy and immunotherapy. Some genomic profiles indicate whether a cancer is likely to be sensitive or resistant to certain chemotherapy drugs, allowing doctors to choose the most effective option. For immunotherapy, which harnesses the body’s immune system to fight cancer, genomic tests identify biomarkers that suggest a patient is likely to benefit. This includes assessing tumor mutational burden (TMB) or microsatellite instability (MSI), which can predict response to immune checkpoint inhibitors.
Genomic insights can also reveal potential mechanisms of resistance to current treatments, informing therapy adjustments. They can also identify a patient’s eligibility for clinical trials exploring new treatments based on their specific genomic profile. This personalized approach aims to optimize treatment outcomes by matching the right therapy to the right patient, based on the unique molecular characteristics of their cancer.
When Genomic Testing is Considered
Genomic testing is often considered for patients with advanced, metastatic, or difficult-to-treat cancers, particularly when standard treatments have not been effective. Understanding the specific genomic alterations can open up new treatment avenues, including targeted therapies or immunotherapies. It is also recommended for certain cancer types where specific genomic alterations are “actionable,” meaning approved therapies directly target those changes.
The decision to pursue genomic testing is a collaborative one, involving the patient and their care team. It is based on several factors, including the type and stage of cancer, previous treatment history, and the potential availability of targeted therapies or clinical trials. While not every cancer type routinely undergoes comprehensive genomic profiling, its utility is growing, especially for solid tumors that are advanced or have spread. This testing helps ensure that patients receive a personalized and potentially effective treatment strategy.