Impact of visceral pleural invasion on the survival of patients with non-small cell lung cancer.

BACKGROUND

In this study, we investigated visceral pleural invasion (VPI) as a poor prognostic factor in patients with non-small cell lung cancer (NSCLC) according to the 7th edition of the TNM classification.

METHODS

Between January 2000 and December 2007, 886 consecutive patients with pathological T1a-T2b NSCLC underwent complete resection with systematic lymph node dissection in Tokyo Medical University. We statistically analyzed the association between VPI and clinicopathologic factors, or clinical outcomes.

RESULTS

The 5-year overall survival (OS) rates of the pl0, pl1, and pl2 patients were 80.8%, 63.7%, and 49.6%, respectively, with significant differences between pl0 and pl1 (p=0.002), pl1 and pl2 (p=0.03). Thus, the pl1 and pl2 patient groups were defined as patients with VPI. VPI was found to be a significant independent prognostic factor by multivariate survival analysis (p=0.0002). In patients with tumors ≤3 cm, especially with tumors ≤2 cm, VPI was significantly associated with an increased rate of lymph node metastasis, compared with non-VPI (p=0.0003 and p=0.015, respectively). Analysis of the OS of patients stratified by tumor size (≤3 cm, 3.1-5 cm, 5.1-7 cm) and VPI status showed that in any nodal status, patients with 3.1-5 cm/VPI tumors had significantly worse survival than patients with ≤3 cm/VPI tumors (p=0.019) and patients with 3.1-5 cm/non-VPI tumors (p=0.001). On the other hand, there was no significant difference in the OS between patients with 3.1-5 cm/VPI tumors and patients with 5.1-7 cm tumors regardless of lymph node metastasis (T2b tumors). Similar relationships were observed among these groups with N0 disease.

CONCLUSION

We identified the presence of VPI as an independent poor prognostic factor in patients with NSCLC of ≤7 cm. Tumors 3.1-5cm with VPI should be upstaged to T2b tumors in the future in the TNM classification of the Union of International Cancer Control staging system. In addition, the surgical strategy involving more extensive lymph node dissection for patients with ≤3 cm/VPI tumors, especially ≤2 cm/VPI, is warranted owing to more frequent lymph node metastasis.