OBJECTIVETo investigate the prognostic significance of micrometastasis (MM) in peripheral blood of patients with non-small cell lung cancer (NSCLC) treated by chemo-radiation therapy.

METHODSPeripheral blood was taken from 67 NSCLC patients before and after definitive chemo-radiation therapy. CK19 mRNA of the peripheral blood was measured by nested RT-PCR and both their relationship with clinicopathological features and prognostic significance were further investigated.

RESULTSThe micrometastasis-positive rates were 65.7% (44/67) and 32.8% (22/67), respectively, before and after the treatment. The micrometastasis-positive rate before treatment was closely in correlation with N-stage (P = 0.014). In contrast, it turned out to be more closely related with histological types (P = 0.019), weight loss (P = 0.01), KPS status (P = 0.027) as well as N-stage (P = 0.032) after chemo-radiation therapy. 4-yr distant metastasis rates (DMR) for micrometastasis-positive and -negative patients were 78.3% and 70.4%, respectively, before the treatment (P = 0.544) while they were 100% and 62.9%, respectively, after the chemoradiation (P < 0.001). The median survival time (MST) and 4-yr overall survival rate (OSR) for pretreatment micrometastasis-positive and -negative patients were 13.8 months and 17.6 months, and 18.2% and 17.4%, respectively (P = 0.619), while for post-treatment micrometastasis-positive and -negative patients they were 7.8 months and 27.6 months and 0 and 26.4%, respectively (P < 0.001). Multivariate analysis showed that the post-treatment positive micrometastasis was an independent unfavorable prognostic factor (P = 0.000).

CONCLUSIONDetection of micrometastasis in peripheral blood may possess a prognostic significance after definitive chemo-radiation therapy. Micrometastasis-negative patients have better prognosis compared to those with positive micrometastasis.