Early results of a comparative study of techniques for intraoperative pleural lavage cytology in NSCLC : methodology matters

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Poncelet AJ, Coulon C, Cornet J, Noirhomme Ph, Collard Ph, Weynand B

 

Cliniques Universitaires Saint-Luc, Bruxelles

Objectives: Pleural lavage cytology (PLC) positivity has been shown to adversely affect patient survival. The prevalence of positive PLC varies among studies from 4.5% to 17%. We hypothesized that methodology could explain part of those discrepancies

Methods: In Group A (n=73), before any tumor dissection or lobar mobilization, 100ml of 0.9% NaCl solution was added into the thoracic cavity, recovered and immediately fixed in alcohol at a 50% concentration, than centrifuged and stained according to Papanicolaiou’s method (Class 1 to 5). In Group B (n=12), 1000ml of 0.9% NaCl solution was added into the thoracic cavity and recovered. The centrifuged material was fixed in 10% formaldehyde, embedded in paraffin, stained with H&E as well as with specific IHC markers

Results: From 1998 to 2007, we performed PLC in 85 surgical patients (stage I, n= 63 and II, n= 22). All resections were complete. WHO histology showed adenocarcinoma in 50% and squamous cell carcinoma in 41.7%. Tumor differentiation was good, moderate and poor in 30.6%, 48.2% and 21.2%, respectively. Group A and B were similar in terms of stage, histology, grade and surgical procedures. The mean tumor diameter in Group A and B were 4.5± 3.4 and 4.3± 2.8 cm (p= 0.88). The incidence of positive PLC in group A and B were respectively 0% and 14.1% (2/12) (p=0.018- Fisher exact test)

Conclusions: This preliminary study shows that the incidence of positive PLC varies according to the methodology and further highlights the need for technique standardization before any definitive conclusion be made on its prognostic value in NSCLC.