Background: The use of molecular markers in staging non-small cell lung cancer (NSCLC) has been supported in retrospective prognostic models but has not been evaluated in predicting sites of metastases.
Methods: Pathologic specimens were collected from 202 patients after complete resection for stage I NSCLC, who were subsequently found to have no metastases at 5 years (n = 108), isolated brain metastases (n = 25), or other distant metastases (n = 69). A panel of eight molecular markers of metastatic potential was chosen for immunohistochemical analysis of the tumor: p53, erbB2, angiogenesis factor viii, EphA2, E-cadherin, urokinase plasminogen activator (UPA), UPA receptor, and plasminogen activator inhibitor.
Results: Patients with isolated brain relapse had significantly higher expression of p53 (p = 0.02) and UPA (p = 0.002). The quantitative expression of E-cadherin was used to predict the site of metastases using recursive partitioning: 0 of 92 patients with E-cadherin expression of 0, 1, or 2 developed isolated cerebral metastases; 0 of 33 patients with E-cadherin expression of 3 with UPA of 1 or 2 and ErbB2 of 0 developed brain metastases. Of the remaining patients at risk (UPA = 3), the risk of isolated cerebral metastases was 21 of 57 patients (37%).
Conclusions: This study demonstrates that molecular markers may predict the site of relapse in early stage NSCLC. If validated in an ongoing prospective study, these results could be used to select patients with isolated brain metastases for adjuvant therapy, such as prophylactic cranial irradiation.