PURPOSE: Several reports have suggested the importance of pleural lavage cytology examined at the operation (PLC) for a prognostic indicator. But its reliability is still in argumentation. The purpose of this study is to evaluate a usefulness of PLC examined in clinical practice.
METHODS: Multi-institutional retrospective database analysis was performed and 1830 cases were registered from 6 institutes, in which PLC have been routinely examined immediately after thoracotomy for non small cell lung cancer. Cases with pleural effusion were excluded. Out of 1830, 106 cases were PLC positive and all PLC negative cases were registered in control group. Survival difference is assessed by logrank test and significance of eight prognostic factors is analyzed with Cox proportional hazard model (Cox analysis).
RESULTS: Age and stage have a statistical difference (p=0.016 and p=0.008, respectively) in background analysis. Survival curve of PLC positive group was significantly worse in both over-all survival (p=0.002) and disease free survival (p< 0.001). The incidence of recurrence with pleuritis carcinomatosa was significantly high (p< 0.001). Cox analysis revealed age, gender, tumor size, N score and PL score are significant (p< 0.001) for overall survival, and tumor size, N score and PL score are significant (p< 0.001) for disease free survival. Positive PLC is not a good prognostic factor by itself (p=0.328), but is useful increasing the accuracy of PL score. The PLC positive curve is similar to that of stage IIB in survival curve analysis. By Cox analysis, F value is largest (F=34.40) when PL score is adjusted to PL2 for PLC positive case. But adjustment to PL3 is also acceptable (F=34.35), whereas F value is 32.19 in unadjusted condition and 31.32 in PL4. These results suggested that PLC positive should be evaluated as PL3.
CONCLUSION: PLC is not a good prognostic factor by itself, but useful to increase the accuracy of PL sore.
CLINICAL IMPLICATIONS: PLC positive is a preliminary state connecting to the malignant pleural effusion and should be evaluated as PL3.
DISCLOSURE: Masanori Kaneda, No Financial Disclosure Information; No Product/Research Disclosure Information