Should three slide-touch print cytology replace pleural lavage cytology for detection of pleural micrometastases in cases of bronchogenic carcinoma?

A prospective study, including 112 patients, designed to estimate the sensitivity and specificity of slide-touch and pleural lavage cytology for diagnosis of pleural micrometastases in operable non-small cell lung cancer (NSCLC). Histopathologically, excised tumors showed P0 in 22 patients (19%), P1 in 44 patients (39%), P2 in 32 patients (29%), P3 in 14 patients (13%). Cytological examination of the three slide-touch prints from visceral pleura overlying the tumor (slide 1), parietal pleura facing tumor (slide 2), parietal pleura in paravertebral gutter (slide 3) resulted in: slide 1: positive in 60% (66/112) [this included p0 (2 out of 22), p1 (22 out of 44), p2 (32 out of 32) and p3 (10 out of 14)], slide 2: positive in 13% (14/112); all of them had P3, and slide 3 positive in 8% (9/112). Total positive slides 62% (70/112). Pleural lavage: positive in 19% (22/112), all of them were detected with slide 1 and/or slide 2. During follow-up, patients with negative slides had no local or distant metastases (truly negative), six recurrences among those with positive slide 1, including four with positive lavage. Thus, slide touch print is more sensitive than lavage cytology, both of prognostic significance. Slide 1 is a highly sensitive detector of visceral pleural micrometastases; slide 2 is a more sensitive detector of parietal pleural invasion; slide 3 is the least.