Biomarkers of the insulin-like growth factor pathway predict progression and outcome in lung cancer.

Background: Insulin-like growth factor 1 (IGF-I), IGF binding proteins (IGFBP) 1 to 7, and C-peptide have been postulated to predict survival in non-small cell lung cancer (NSCLC). Studying serum levels in NSCLC patients treated with surgical resection may provide information on the aggressiveness of tumors and be predictive of disease recurrence.

Methods: Immunobead assays were used to measure pretreatment serum levels of IGF-I, IGFBP1 to IGFBP7, and C-peptide in 100 NSCLC patients. Of these, 59 had no metastatic progression (T1 to T4 N0 M0), whereas 41 had positive lymph nodes (T1 to T4 N1 to N3 M0). Data were analyzed using the Mann-Whitney two-sided rank sum test or Kaplan-Meier curves.

Results: Low serum IGFBP5 levels correlated strongly with a positive nodal status (p < 0.001) and any incidence of disease recurrence (p = 0.003). Low serum levels of IGFBP5 also predicted poor recurrence-free survivals in the overall cohort (p ≤ 0.001) and in patients with no nodal metastases (p = 0.027). Conversely, a high serum level of IGFBP7 correlated with positive nodal status (p = 0.008), but was not prognostic for recurrence-free survival. No significant correlations were found for IGFBP5 or IGFBP7 for sex, age, race, smoking history, tumor histology, or fasting state.

Conclusions: IGFBP5 and IGFBP7 had value as biomarkers for identifying NSCLC progression and patient outcome.