Cancer is the malignant menace that has affected humanity for centuries, it is not a single disease but a collection of disorders with a common trait – uncontrolled cell growth. For a long time, the mysteries locked within our genetic code seemed impenetrable. But today, thanks to an advanced technology called Next Generation Sequencing (NGS), we are closer than ever to cracking cancer’s code. For those who like a longer read or deeper delve into the topic, I recommend “The Emperor of All Maladies”, “The Song of the Cell” and “The Gene” by Dr Mukherjee. For everyone else, I hope this article helps patients and families understand genetic testing and its utility in the clinic, especially for those dealing with metastatic disease.
What is Next Generation Sequencing (NGS)?
Imagine reading a book – an exceptionally long book, three billion letters long, with no space or punctuation. That is what our DNA looks like. NGS is like a powerful magnifying glass, able to read this book with incredible precision. Traditional sequencing methods could only read small parts of this book at a time. But NGS allows scientists to read millions of DNA strands simultaneously, generating a huge amount of data, identifying mutations or variations that could be leading to uncontrolled cell growth – the hallmark of cancer. It is like looking under the hood of the car and finding the specific alteration that can be targeted from a therapeutic standpoint.
How is NGS performed with Tumor Tissue or Liquid Biopsies?
Next, let us talk about where we get the ‘book’ for sequencing. Two main sources are tissue and blood samples. Tissue samples are obtained directly from the tumor, typically via a biopsy or during surgery. These samples are then processed in a laboratory where the DNA is extracted and sequenced. Think of it as obtaining a copy of the ‘book’ straight from the main library. Sometimes we can use tissues already obtained from a previous biopsy or surgery. Most often, it is best to use fresh tissue. On the other hand, liquid biopsies, a less invasive method, involve drawing blood and looking for fragments of tumor DNA circulating in the bloodstream. These DNA fragments can be thought of as ‘borrowed books’ from the main library, floating freely for us to find and read. After the analysis is complete, a complete report is sent to the ordering physician or medical oncologist. To most folks who are looking at the report, it may appear to look like an “alphabet soup” collection with words like EGFR, BRAF, HER2, ALK, ROS, fusions, deletions, insertions, amplifications, etc. To most medical oncologist, this has become more common place with potentially uncovering biomarkers for better treatments beyond just traditional chemotherapy.
Where Can NGS be Done?
Think of NGS as a powerful microscope that needs a specialized lab and skilled technicians. These facilities are usually located in research institutions and certain hospitals. However, various third-party vendors, like Illumina or 10x Genomics, also provide NGS services. It is like taking our ‘book’ to a professional proof-reader, ensuring the task is performed with utmost accuracy. Today, there are many third-party companies that complete this within 3-4 weeks. Foundation One, Tempus, Altera, etc. Many cancer centers, including our hospital can do this in house.
Why Do Medical Oncologists Order NGS?
Picture your oncologist as a detective trying to solve a mystery. The ‘clues’ lie in the tumor’s DNA, and NGS helps find these clues. By identifying specific mutations in a tumor, oncologists can select the most effective treatment strategies, monitor disease progression, and even identify minimal residual disease after treatment. Moreover, it could also reveal opportunities for patients to participate in specific clinical trials. It is ok to review this report with your oncologist. Do not be afraid to ask why the report was or was not helpful in your case.
How does NGS Help Patients and Providers in Cancer Treatment?
NGS ushers in a new era of personalized medicine, enabling treatment to be tailored to the unique genetic profile of a patient’s tumor. It is like having a custom-made key for a particular lock, increasing the chances of successful treatment. By understanding a tumor’s genetic composition, oncologists can deploy targeted therapies or immunotherapy, increasing effectiveness and reducing side-effects. Additionally, NGS allows monitoring disease response to treatment, and changes in the tumor’s DNA over time can indicate whether a treatment is working or if the disease is progressing.
The field of oncology stands on the brink of a revolution, propelled by technologies like Next Generation Sequencing. While it is not a magic bullet that will cure all cancers, it represents a significant leap towards understanding and managing this complex set of diseases more effectively. The hope is that one day, with the help of NGS and personalized medicine, we will transform cancer from a deadly disease into a manageable condition.
About the author
Dr. Sajeve Thomas is a distinguished medical professional and a compassionate guide in the field of oncology. With over a decade of dedicated experience as a board-certified medical oncologist/internal medicine specialist, Dr. Thomas has become a trusted expert in the treatment of melanoma, sarcoma, and gastrointestinal conditions. Currently practicing at the renowned Orlando Health Cancer Institute, he brings a wealth of expertise to the complex and challenging world of oncology.