Genomic Testing in Cancer Care
Next-generation sequencing techniques, also referred to as genomic testing, allow medical professionals to analyze a person's entire DNA or genome. By looking at the genetic changes in a tumor sample compared to normal cells, genomic testing can provide crucial information about the molecular characteristics of a patient's specific cancer. This personalized molecular profile can help guide treatment decisions and identify targeted therapies that may work best based on a tumor's genomic alterations.
What Types of Genomic Testing Are Used in Cancer Care?
There are a few main types of Genomic Cancer Testing that are increasingly being used in clinical oncology to characterize cancers at a molecular level:
Targeted gene panels sequence a predefined set of genes known to be drivers of specific cancer types or tumor signaling pathways. This focused approach analyzes the most important and actionable gene regions for a particular cancer.
Comprehensive genomic profiling sequences all of the DNA across a patient's entire genome or hundreds of cancer-related genes simultaneously. This broad scope allows an unbiased look at all potential genomic alterations in a tumor sample beyond predetermined gene panels.
Whole genome sequencing analyzes the complete DNA sequence of all three billion base pairs in a person or tumor's genome. This most in-depth genomic test provides an unparalleled understanding of all mutations, including structural variants and newly identified cancer genes, but comes at a higher cost than targeted panels or profiling.
What Information Can Genomic Testing Reveal for Cancer Patients?
Genomic analysis of cancer tumor DNA can reveal important clinical insights that can directly impact treatment decisions:
Molecular Profiling for Precision Medicine
By characterizing the genomic alterations that are driving a patient's specific cancer, genomic testing facilitates precision or personalized treatment approaches. Matching a patient's molecular profile to targeted drugs designed for their tumor's genetic abnormalities and pathways can significantly improve response rates compared to conventional chemotherapy alone.
Detection of Biomarkers for Immunotherapy
Genomic analysis can identify biomarkers like microsatellite instability (MSI) or tumor mutational burden (TMB) that predict whether a patient may benefit from immune checkpoint inhibitors like pembrolizumab or nivolumab. Such immunotherapy biomarkers are playing an increasing role in multiple cancer types.
Identification of Rare Genomic Alterations
Rare genomic variants that may be druggable targets can be discovered through comprehensive genomic profiling techniques. Finding these "needles in a haystack" allows more patients to receive matched targeted therapies through ongoing clinical trials or expanded access programs.
Assessment of Prognosis and Risk Prediction
Genomic classifiers developed from large patient datasets have demonstrated utility in cancer subtyping as well as predicting risk of disease recurrence or progression after standard therapies. These molecular prognosis tools allow for more informed clinical management decisions.
Monitoring of Minimal Residual Disease
Serial genomic blood or liquid biopsies allow noninvasive monitoring to detect residual or recurrent cancer at an early, potentially curable stage through monitoring for cancer-specific genomic alterations. This emerging application shows promise for improving treatment response assessments.
How Are Genomic Testing Results Used in Treatment Planning?
Actionable genomic results from broad profiling have been directly integrated into clinical decision making through several approaches:
1. Matching molecular alterations to available targeted drugs: Patients may receive FDA-approved or clinical trial therapies directly targeting genomic abnormalities specifically detected in their tumor. Examples include EGFR or ALK inhibitors for lung cancers.
2. Enrolling in genomic-matched clinical trials: Often referred to as "biomarker-selected" or "molecularly-driven" trials, these studies test targeted drugs based on genomic eligibility criteria rather than tumor type alone.
3. Access to expanded therapies: Compassionate use programs and commercial molecular tumor boards allow treatment access predicated on an unusual or rare "actionable" genomic finding, not just standard-of-care biomarker tests.
4. Optimizing sequential therapy regimens: As cancer inevitably develops resistance, repeated genomic profiling of recurrent disease enables switching between multiple targeted treatment lines guided by each sample's separate molecular profile.
5. Future planning based on prognosis and recurrence risk: While initially only a prediction, time will tell whether management guided by genomic prognosis tools results in meaningfully altered outcomes. Concurrent research continues refining their accuracy and implementation.
Genomic cancer testing is enabling a new era of oncology where molecular characterizations of an individual's specific cancer are leveraged to provide the most customized therapy options available. Paired with constantly improving interpretation and clinical validation, genomic testing promises to transform cancer care into a form of personalized medicine. With deeper understanding comes the potential for improved survival rates through targeted, molecularly-guided treatment strategies.
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