Circulating tumor cells (CTCs) could be a promising biomarker for progressive or recurrent disease in locally advanced non-small cell lung cancer (LA-NSCLC), according to new findings presented at the 2017 Multidisciplinary Thoracic Cancers Symposium.
In what is described as the largest prospective clinical trial to date evaluating the use of CTCs in lung cancer, CTCs detected recurrences of lung cancer before imaging showed any evidence of it.
"CTC monitoring in patients undergoing chemoradiation for locally advanced NSCLC is feasible," said lead author, Chimbu Chinniah, a research fellow in radiation oncology in the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.
"CTC elevations in many patients meaningfully precede radiologic evidence of disease recurrence and may be a promising biomarker of progressive or recurrent disease to help guide early salvage therapeutic strategies," Chinniah said during a press briefing.
The idea of using CTCs as a "liquid biopsy" to monitor treatment and assess outcomes has been gaining momentum in cancer research over the past few years, and for several cancer types.
This latest study was a prospective clinical trial that included 48 patients with stage I to III LA-NSCLC who had been treated with concurrent chemoradiation. Within this group, 48% had squamous cell carcinoma and 46% had adenocarcinoma, and the median primary tumor size was 3.7 cm (range, 1.5 to 10.0 cm).
More than half (54%) of the patients had stage IIIA disease, and 33% had stage IIIB with cN2 (60%) or cN3 (23%) nodal disease.
Blood samples were obtained before the patients underwent treatment, during treatment (at weeks 2, 4, and 6), and after treatment ended (at months 1, 3, 6, 12, 18, and 24). Surveillance scans with computed tomography (CT) or positron emission tomography (PET)/CT were obtained at 3-month intervals.
At a median follow-up of 10.9 months, disease recurred in 22 patients (46%). The median time to recurrence was 7.6 months (range, 1.3 to 32 months).
Blood samples were obtained after chemoradiation therapy for 20 of the 22 of the patients whose disease recurred.
Of these 20 patients, 15 had elevated CTC counts after treatment, with a median lead time of 4.7 months (range, 1.2 months to 1 year) between the increase in CTCs and radiographic evidence of recurrence.
"Two thirds of recurrent patients demonstrated a rise in CTC counts an average of 6 months before PET/CT or CT scans detected the recurrence," said Chinniah.
One patient who experienced an early recurrence (at 4.7 months) had persistently elevated CTC levels both during and after treatment, and 4 patients experienced recurrences that were detected with imaging before their CTC levels began to rise.
"Future research is needed to test whether the early detection of disease recurrence afforded by CTC analysis translates to improved outcomes," concluded Chinniah.
Commenting on the study, press briefing moderator Ravi Salgia, MD, PhD, from the City of Hope, Duarte, California, noted that "we need to pay attention to individualized therapy."
"And as we go forward with individualized therapy, we need to be looking out for biomarkers," he said. "How do we go forward in this era of genomics and precision medicine?"
"Breast cancer has been ahead of us but now lung cancer is catching up," Dr Salgia explained. "Circulating tumor cells in lung cancer are here to stay and we have to look at them as a biomarker."
Mr. Chinniah has no disclosures; several of the coauthors have relationships with industry as noted in the abstract.
2017 Multidisciplinary Thoracic Cancers Symposium.