Unlike advanced ADCL, the role of cfDNA in operable ADCL is unclear and this study was aimed to evaluate the feasibility for identification of cfDNA in pleural lavage fluid and its correlation with plasma in resectable ADCL.
Consecutively resected ADCL within a period of 24 months were evaluated for cfDNA levels in preoperative plasma (Pre-P), intraoperative pleural lavage (IP-L) and postoperative (at 1 month) plasma sample (Post-P). CfDNA was isolated from the stored pleural lavage and plasma using QIAamp DNA Blood Mini Kit (QIAGEN). DNA extracted plasma and pleural lavage DNA were measured quantitatively by qPCR in a TaqMan probe detection approach using the human β-actin gene as the amplifying target.
All of the study patients (n=23) were negative for malignant cells in IP-L cytology. The median cfDNA levels in Pre-P, IP-L and Post-P were 83.1ng/ml, 153.5ng/ml and 88.0ng/ml respectively. A positive correlation was demonstrated between Pre-P and IP-L levels (correlation coefficient r= 0.478, p=0.007). A significant overall survival (OS) and disease-free survival (DFS) was recorded for patients with cfDNA level cut-offs at 125ng/ml, 175ng/ml and 100ng/ml respectively for Pre-P, IP-L and Post-P. The area under the curve (AUC) for IP-L with DFS was found to be at a significant range (AUC=0.901, Standard error rate=0.050). Tumors with stage >T2 produced significantly more cfDNA levels in IP-L (p=0.033). The median OS was 23.7 months. Patients with raised cfDNA in Pre-P (>125ng/ml) and IP-L (>175ng/ml) had a significantly poorer 2-year OS, p=0.026 and p=0.037 respectively. The hazards (OS) were also higher for those with raised cfDNA in IP-L (HR=6.821, 95%CI=0.989-12.796, p=0.050). The median DFS was 16.9 months. A raised IP-L (>175ng/ml) correlated significantly with poorer DFS at 2-years (p=0.003) and a significant increase in hazards of DFS (HR=11.455, 95% CI=1.395-24.434, p=0.023). Multivariate analysis suggested higher IP-L as a poor prognostic factor for both OS and DFS.
Among patients with operable ADCL, cfDNA in pleural lavage can be a reliable biomarker for both recurrence and overall survival, with IP-L cfDNA levels possibly a better indicator than plasma cfDNA levels.
Legal entity responsible for the study
Has not received any funding.
All authors have declared no conflicts of interest.