New study findings presented at the 2017 Multidisciplinary Thoracic Cancers Symposium point towards using circulating cells as a biomarker for lung cancer recurrence. Specifically, the results suggest that circulating tumor cells, or CTCs, could detect the progression or recurrence of lung cancer for individuals with locally advanced non-small cell lung cancer (LA-NSCLC). The information comes from the largest prospective clinical trial thus far surrounding CTCs.
“CTC monitoring in patients undergoing chemoradiation for locally advanced NSCLC is feasible. 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. 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.”
-Lead author, Chimbu Chinniah, research fellow in radiation oncology at the Perelman School of Medicine at the University of Pennsylvania, Philadelphia
In the study, 48 individuals with stage I to stage III LA-NSCLC, who had been treated with concurrent chemoradiation, were monitored for changes in CTC levels. The most common cancer types were squamous cell carcinoma and adenocarcinoma, with a median primary tumor size of 3.7 cm. The majority of individuals had stage IIIA or IIIB LC, and had cN2 or cN3 nodal disease.
A Liquid Biopsy?
CTCs were used as a liquid biopsy of sorts, which is a technique that is gaining traction for many different cancer types over the past several years. Blood samples to measure CTC levels were taken before treatment, during treatment, and after treatment. The samples during treatment were taken during weeks 2, 4, and 6, and the after treatment samples were taken during months 1, 3, 6, 12, 18, and 24 post-treatment. CT and CT/PET scans were taken to assess lung cancer recurrence and/or progress every 3 months.
The median follow-up time was 10.9 months, and 46% of patients experienced lung cancer recurrence. The median time for this recurrence was 7.6 months. The most notable part of the study comes from the blood sample results for the patients with recurrence. Elevated CTC counts were found after treatment for 20 out of 22 patients with recurrence. Further, a median lead time of 4.7 months was found between CTC level increases and imaging evidence of lung cancer recurrence. Essentially, this means that for most patients, recurrence could be detected earlier by monitoring CTC levels in the blood.
Further testing needs to be completed to strengthen this potential link, and to determine how it could contribute to improving health outcomes for individuals with lung cancer. While there is still much more to be done, many are very excited with the potential discovery of a new, reliable biomarker.1