Cytoplasmic and nuclear parathyroid hormone-related proteins are opposing prognostic factors in patients with non-small-cell lung cancer who have undergone curative resection

Abstract

Objective: Parathyroid hormone-like related protein was a prognostic factor for non-small-cell lung cancer, but the results were conflicting. The present study was to examine the role of cytoplasmic and nuclear parathyroid hormone-like related protein in patients with non-small-cell lung cancer who have undergone surgical therapy.

Methods: The expression of parathyroid hormone-like related protein was examined by immunohistochemical staining in 56 patients with resectable non-small-cell lung cancer. The impact of parathyroid hormone-like related protein expression on cancer recurrence and survival was assessed in combination with clinicopathologic features.

Results: Patients with a high expression of cytoplasmic parathyroid hormone-like related protein had a significantly unfavorable prognosis in both disease-free survival (median 16.7 vs. 58.0 months, P = 0.029) and overall survival (median 31.6 months vs. not reached, P = 0.046). In contrast, the patients with high expression of nuclear parathyroid hormone-like related protein had favorable disease-free survival (median 35.1 vs. 19.9 months, P = 0.069) and a significantly better overall survival (median not reached vs. 36.9 months, P = 0.033). There was no correlation between the expression of cytoplasmic and nuclear parathyroid hormone-like related protein (P = 1.00). Furthermore, multivariate analysis using a Cox regression model confirmed that high expression of cytoplasmic parathyroid hormone-like related protein (disease-free survival, hazard ratio: 1.973, P = 0.079; overall survival, hazard ratio: 2.461, P = 0.067) and nuclear parathyroid hormone-like related protein (disease-free survival, hazard ratio: 0.436, P = 0.029; overall survival, hazard ratio: 0.375, P = 0.018) were independently prognostic factors for disease-free survival and overall survival.

Conclusion: Cytoplasmic and nuclear parathyroid hormone-like related protein play opposing prognostic roles for the disease-free survival and overall survival of patients with early non-small-cell lung cancer who have undergone curative resection.

Keywords: PTHrP; non-small-cell lung cancer; prognostic factor.