The current standard of care for identifying targetable mutations in cancer treatment is to conduct molecular profiles on tumour tissue samples, but a study published Monday in JAMA Network Open indicates that adding liquid biopsy testing for circulating tumour DNA mutations increases targetable mutation detection rates.

For example, in patients with breast cancer, fragments of DNA circulating in the bloodstream released from cancer cells had significantly higher detection rates than tissue samples for an ESR1 mutation, indicating resistance to a common breast cancer treatment.

The liquid biopsy detection rate was 24.7% higher for the ESR1 mutation than the tissue sample rate.

“This large database study demonstrates the clinical utility of completing both liquid and tissue biopsies in patients with cancer in order to optimise identification of important cancer mutations that impact treatment decisions,” said Wade Iams, MD, assistant professor of Medicine at Vanderbilt-Ingram Cancer Center, first author of the study.

Researchers performed next generation sequencing on tumour tissue and blood samples from 3,209 patients to check for mutations that impact guideline-based treatment decisions.

The patient sample was ethnically diverse.

White patients comprised 48% of the group, African American patients, 9%, Latino patients, 5.6%, Asian patients, 3% and other self-identified ethnicities, 3%. The ethnicity was unknown for 31.4% of patients.

The study is believed to be the largest advanced multicancer, solid tumour study to date that examines the results of concurrent next generation sequencing for both circulating tumour DNA and tumour tissue.

The patients, whose medical records were deidentified, had metastatic non-small cell lung cancer, breast cancer, prostate cancer, or colorectal cancer.

Although variant detection by both testing methods was largely concordant, for each cancer type, unique mutations that impact treatment decisions were seen in both tissue and liquid biopsies.

The researchers concluded that the study indicates that concurrent testing with both liquid biopsies and tissue samples is “feasible and clinically beneficial for detecting more actionable variants among patients with advanced cancer.”

Source: Vanderbilt-Ingram Cancer Center