How Gene Sequencing Works

Gene sequencing — in particular, Next-Generation Sequencing (NGS) — is the newest enhancement to the Swedish Cancer Institute’s tradition of innovation.

The Swedish Cancer Institute is already well known for personalizing treatment plans because of the availability of multiple drug therapies, sophisticated surgical procedures and one of the most extensive selections of radiation therapies on the West Coast.

Now, gene sequencing allows our cancer specialists to personalize their patients’ treatment plans down to the cellular level.

How Does Gene Sequencing Work?

First, a small tissue sample is collected from the tumor. It can come from a biopsy or as a result of surgery to remove or reduce the size of the tumor. The tissue sample is sent to a laboratory where the newest state-of-the-art equipment pulls out the DNA to determine the order (or sequence) of the various components that comprise that specific strand of DNA. This process identifies any abnormalities in the genes in the tumor cell’s DNA.

When gene sequencing was first introduced in the early 1990s, it was a slow and rather cumbersome process. Today, sequencing is accomplished using new technology called Next-Generation Sequencing or NGS. NGS has the ability to evaluate many more strands of DNA in a shorter amount of time.

The Swedish Cancer Institute and its partner CellNetix, the local laboratory where Swedish’s gene sequencing occurs, have specifically selected a panel of 68 genes to study. This panel of genes represents many different types of cancers, including those found in the brain, breast, colon, ovaries, skin and lungs, as well as other types of tumors. It also includes blood cancers, such as leukemia and lymphoma. The panel also represents those gene abnormalities for which there are treatment options that offer promising results. As the research into gene abnormalities and treatments progresses, the panel will be expanded to include additional genes.

How Is Gene Sequencing Used for Cancer Care?

A pathologist analyzes the information collected through gene sequencing and using existing databases looks for other examples of the same abnormality. The databases also contain information about treatments that work best on certain abnormalities and clinical trials of new treatments for that particular type of cancer.

After analyzing the data, the pathologist sends a report to the patient’s cancer specialist. The report contains the gene sequencing information, results of other microscopic studies and tests on the tumor tissue, possible treatment options and available clinical trials.

The cancer specialist uses the report, the patient’s medical and family history, drug tolerance, surgical limitations and results of prior treatments, if any, to create a treatment plan that is personalized for that particular patient.

Why Is Gene Sequencing Important?

Zeroing in on the best treatment — right from the start — is the most effective and efficient way to treat cancer. A gene-sequencing report identifies treatment options that have been effective for other patients with the same gene abnormality. This information helps avoid potentially ineffective treatments and gets the patient on the correct treatment pathway more quickly.

Gene sequencing may also help reduce the side effects that are often associated with treatments that aren’t able to differentiate between cancer cells and healthy cells. A gene-sequencing report lists available therapies that target the identified abnormal gene and have a minimal effect on the patient’s healthy cells.

As these therapies are studied and tested through clinical trials, cancer specialists learn more about how the newest drugs and treatment options might benefit other patients who have had the same or similar gene-sequencing results.