Objective: The aim of the present prospective study was to evaluate the correlation between the change of serum c-reactive protein (CRP) levels and response to chemotherapy in patients with locally advanced or metastatic non-small cell lung cancer.
Material and Method: Patients with locally advanced or metastatic non-small cell lung cancer who received the first line chemotherapy were measured serum CRP levels prior to treatment. Chemotherapy regimen was given to patients according to physicians and radiologic imaging was evaluated after two or three cycles of treatment. Serum CRP levels were measured first time at pre-treatment and second time in patients who had pre-treatment serum CRP levels greater than normal range (3 mg/l) at the time of response assessment or clinical progression. The primary end point was the correlation between change of serum CRP levels and radiologic response. The secondary end point was the prevalence of elevated CRP levels in advanced NSCLC patients and correlation between initial CRP levels and progression free survival (PFS).
Results: Fifty four patients were enrolled. Prevalence of elevated CRP levels in advanced NSCLC was 76%. Thirty patients had serial serum CRP measured. There was correlation between change in serum CRP levels and response to treatment (r = 0.43, p = 0.018, spearman rank). There was significant correlation between response to treatment and decrease in CRP levels greater than 50% (p = 0.009, Fisher’s exact test). In contrast there was no correlation between progression and increase in CRP levels (p = 0.640, Fisher’s exact test). All patients with serial CRP levels decreased to normal range (< 3mg/l) had response to chemotherapy. High pre-treatment CRP levels (> 100 mg/l) correlated with poor PFS. Median PFS for patients with pre-treatment CRP levels of 3-30 mg/l, 30-100 mg/l and >100 mg/l was 23.0 weeks, 13.0 weeks and 6.3 weeks, respectively. Patients with serial CRP levels less than 3 mg/l had greater PFS than patients with serial CRP levels higher than 3 mg/l (p = 0.026, log rank test).
Conclusion: The present study suggested that high levels of pre-treatment serum CRP and persistent CRP in serum was a poor prognostic factor. The decrease in CRP levels greater than 50% was a simple method to predict the response to treatment in patients with locally advanced or metastatic non-small lung cancer.

Keywords: C-reactive protein, Lung cancer