VIDEO: Circulating tumor DNA testing shows real-world limits

GENEVA – Circulating tumor DNA currently has one role to play in routine management of lung cancer patients: To check at the time of diagnosis for a treatment-defining mutation in the tumor’s epidermal growth factor receptor gene, but only when the DNA available from the tumor biopsy is inadequate for analysis, Dr. Egbert F. Smith said in a video interview at the European Lung Cancer Congress. That happens for about 10%-25% of newly diagnosed lung-cancer patients, he said.

Dr. Smit, the designated discussant for the Europe-Japan Diagnostic Study for EGFR [epidermal growth factor receptor] Testing (ASSESS) – a study that ran mutational analysis of the EGFR genes in 1,162 patients using circulating tumor (ct) DNA – highlighted the main limitation of this method in the routine-practice setting used by ASSESS: The test’s low sensitivity of 46%.

He attributed this in part to the wide range of methods used to perform the ctDNA analyses in the international study. “Some methods are sensitive, and some are not so sensitive,” said Dr. Smit, professor of pulmonary medicine at VU University Medical Center, Amsterdam.

“You have to think about the limits of your [ctDNA] test, and the analytical sensitivity of the laboratory,” he said. These factors can make a ctDNA test unreliable for ruling out an EGFR mutation. “Do not think that patients do not have an EGFR mutation based only on their plasma circulating DNA,” Dr. Smit advised.

He had no relevant disclosures.

[email protected]

On Twitter @mitchelzoler

GENEVA – Circulating tumor DNA currently has one role to play in routine management of lung cancer patients: To check at the time of diagnosis for a treatment-defining mutation in the tumor’s epidermal growth factor receptor gene, but only when the DNA available from the tumor biopsy is inadequate for analysis, Dr. Egbert F. Smith said in a video interview at the European Lung Cancer Congress. That happens for about 10%-25% of newly diagnosed lung-cancer patients, he said.

Dr. Smit, the designated discussant for the Europe-Japan Diagnostic Study for EGFR [epidermal growth factor receptor] Testing (ASSESS) – a study that ran mutational analysis of the EGFR genes in 1,162 patients using circulating tumor (ct) DNA – highlighted the main limitation of this method in the routine-practice setting used by ASSESS: The test’s low sensitivity of 46%.

He attributed this in part to the wide range of methods used to perform the ctDNA analyses in the international study. “Some methods are sensitive, and some are not so sensitive,” said Dr. Smit, professor of pulmonary medicine at VU University Medical Center, Amsterdam.

“You have to think about the limits of your [ctDNA] test, and the analytical sensitivity of the laboratory,” he said. These factors can make a ctDNA test unreliable for ruling out an EGFR mutation. “Do not think that patients do not have an EGFR mutation based only on their plasma circulating DNA,” Dr. Smit advised.

He had no relevant disclosures.

[email protected]

On Twitter @mitchelzoler

GENEVA – Circulating tumor DNA currently has one role to play in routine management of lung cancer patients: To check at the time of diagnosis for a treatment-defining mutation in the tumor’s epidermal growth factor receptor gene, but only when the DNA available from the tumor biopsy is inadequate for analysis, Dr. Egbert F. Smith said in a video interview at the European Lung Cancer Congress. That happens for about 10%-25% of newly diagnosed lung-cancer patients, he said.

Dr. Smit, the designated discussant for the Europe-Japan Diagnostic Study for EGFR [epidermal growth factor receptor] Testing (ASSESS) – a study that ran mutational analysis of the EGFR genes in 1,162 patients using circulating tumor (ct) DNA – highlighted the main limitation of this method in the routine-practice setting used by ASSESS: The test’s low sensitivity of 46%.

He attributed this in part to the wide range of methods used to perform the ctDNA analyses in the international study. “Some methods are sensitive, and some are not so sensitive,” said Dr. Smit, professor of pulmonary medicine at VU University Medical Center, Amsterdam.

“You have to think about the limits of your [ctDNA] test, and the analytical sensitivity of the laboratory,” he said. These factors can make a ctDNA test unreliable for ruling out an EGFR mutation. “Do not think that patients do not have an EGFR mutation based only on their plasma circulating DNA,” Dr. Smit advised.

He had no relevant disclosures.

[email protected]

On Twitter @mitchelzoler