Circulating tumor cells monitored over time in lung cancer patients

Abstract

11025 Background: Circulating tumor cell (CTC) detection and enumeration is a valuable tool for monitoring cancer patient status and outcome. While many current techniques employ immunomagnetic-enrichment based protocols focused on the importance of a particular CTC number as the indicator of patient status or outcome, we employ a cytometric, enrichment free approach using an immunofluorescent protocol to monitor CTC counts in patients with non-small cell lung cancer (NSCLC) over the course of treatment. Methods: Eligible patients had progressive stage IV NSCLC. The histological subtypes in the 42 cases for which the data was available included adenocarcinoma (22/42), squamous cell carcinoma (6/42), large cell undifferentiated carcinoma (3/42), and non-small cell lung carcinoma not further described, poorly differentiated, or with a mixed pattern (11/42). Blood samples were collected 3 wks, 3 mo, 6 mo, 9 mo, and 1 yr after the initial sample. CTCs were identified via immunofluorescence and cytometric analysis. Patient response to therapy was determined by RECIST every 3 months between time 0 and time 12 mo. Results: 80 of 109 patient samples have CTCs (73%) and all of the 52 patients tested have CTCs. 13 of 52 patients have CTC data for time 0 and 3 wks. Only 4 of these patients (30.8%) show a correlation linking CTC count change between time 0 and 3 wks and clinical assessment. 13 patients have CTC data for time 0 and 3 mo, 10 of whom show a correlation linking CTC count change between time 0 and 3 mo and clinical assessment. 7 of the 8 patients (87.5%) showing stable or partial response at 3 mo show a decrease in CTC count between time 0 and 3 mo. Five of the 6 patients (83.3%) clinically showing progressive disease at the 3 mo time point show an increase in CTC count between time 0 and 3 mo. The patients that do not show a correlation linking CTC count change between time 0 and 3 mo and clinical assessment at 3 mo show a correlation at the 6 mo time point. Conclusions: CTCs can be effectively enumerated in metastatic NSCLC patients, with the majority demonstrating CTCs in the setting of progressive disease. The change in CTC count at 3 mo, but not at 3 wks, correlates with radiographic response to chemotherapy. Further follow-up will determine the predictive value of CTC enumeration on survival. No significant financial relationships to disclose.