BACKGROUNDTo evaluate the diagnostic value of flow cytometric DNA analysis of sputum cells in lung cancer patients.

METHODSThe DNA content of sputum cells was determined by flow cytometry in 44 patients (29 patients with lung cancer, and 15 patients with benign pulmonary disease). The results of DNA content of sputum cells were compared with those of cytologic morphology of sputum cells.

RESULTSThe last pathologic diagnosis was used as a diagnostic criterion, the sensitivity of DNA heteroploidy analysis was 82.8% , which was significantly higher than that of sputum cytology (82.8% vs 27.6%, P < 0.005); and the positive rate of heteroploidy in sputum samples in stage III and IV disease was significantly higher than that in stage I and II disease (87.5% to 76.9%, P < 0.002 5). In one case, the heteroploidy was found 10 months in advance of cytometry. In the control, heteroploidy was detected in 33.3% (2/6) patients with inflammatory pseudotumor and 50.0% (2/4) patients with tuberculous nodule, who were found with positive staining of Ki67 and PCNA.

CONCLUSIONSFlow cytometry seems to be a valuable adjunctive method for the diagnosis of lung cancer, and probably for the early diagnosis.There are clonal changes in some inflammatory pseudotumor and tuberculous nodule.