ELEVATIONS OF SERUM C-REACTIVE PROTEIN OCCUR INDEPENDENTLY OF CIRCULATING INTERLEUKIN-6 CONCENTRATIONS IN PATIENTS WITH LUNG-CANCER

It has been suggested that a proportion of patients with cancer have a n ongoing acute phase response indicated by a raised C-reactive protei n (CRP). To examine whether an acute phase protein response is associa ted with circulating interleukin-6 (IL-6) concentrations in patients w ith lung cancer, we measured serum levels of CRP and interleukin (IL)- 6 in 176 patients with lung cancer and 48 patients with other pulmonar y diseases (28 diffuse pulmonary infiltrates, 15 benign lung tumors, a nd 5 bronchial asthmas). Serum CRP was detectable (greater-than-or-equ al-to 2.5 mg/liter) in 57.4% of patients with lung cancer, 78.6% of pa tients with diffuse pulmonary infiltrates, 46.7% of patients with beni gn lung tumors, and 40.0% of patients with bronchial asthma. Serum IL- 6 was detectable in all patients by a highly sensitive enzyme-immunoas say, the concentration ranging from 0.126 to 35.115 pg/ml. Although th ere was no significant difference in serum IL-6 levels among the histo logic types of lung cancer, the IL-6 concentration was significantly h igher in patients with advanced cancers than in those with early ones. Correlation analyses showed that there was no significant relationshi p between the CRP and IL-6 concentrations in the 176 patients with lun g cancer (r=0.212, P=0.1243), while a highly significant correlation b etween both levels was observed in the 28 patients with diffuse pulmon ary infiltrates (r=0.783, P=0.0005). These results indicate that the s erum IL-6 level in patients with lung cancer is closely associated wit h the disease stage, but that a raised CRP concentration occurs indepe ndently of circulating IL-6 concentrations in patients with lung cance r.