Ras p21 protein levels in human plasma from patients with chronic obstructive pulmonary disease (COPD) compared with lung cancer patients and healthy controls

To explore the value of an increase in ras p21 proteins in plasma as a biomarker for the carcinogenic process or for the general disease state, we have directly analysed for ras p21 proteins, plasma samples from Polish human patients with chronic obstructive pulmonary disease (COPD). They were compared with appropriate controls and also with the Polish lung cancer patients previously examined before treatment [D. Anderson, J.A. Hughes, A. Cebulska-Wasilewska, E. Nizankowska, B. Graca, Ras oncoproteins in human plasma from lung cancer patients and healthy controls, Mutat. Res. 349 (1996) 121-126]. An elevated level of ras p21 proteins was considered to be greater than 2 standard deviations (SD) above the mean negative control values. Nine out of 20 COPD patients (mean age = 65.9 years) had increased ras p21 protein levels when compared with 20 age-matched (mean age = 62.4 years) controls of the present study with a mean + 2 SD of 0.70, Eighteen out of 40 lung cancer patients (mean age = 60.1 years) had increased ras p21 protein levels compared with their concurrent controls (mean age = 40.2 years) with a mean + 2 SD of 2.53. However when compared with the age-matched controls of this present study, there were 35 out of 40 (87.5%) with increased levels. When the COPD patients and lung cancer patients were compared with 101 historical controls (age range 25-76 years, of those whose age was recorded) from unexposed healthy populations from Poland, Estonia and Spain with a mean + 2 SD of 1.83, then 4 out of 20 (20%) COPD patients and 30 out of 40 (75%) lung cancer patients had increased levels. Whether using concurrent controls, age-matched controls or historical controls, the data would suggest that an increase in ras p21 protein levels in plasma from lung cancer patients could be a possible prognostic marker or biomarker for lung cancer. COPD patients when compared with historical controls or age-matched controls had lower ras p21 protein values than cancer patients. Their ras p21 protein values might also be a biomarker for cancer. It is possible that some of these COPD patients were in the process of developing cancer or perhaps would die from COPD before cancer develops. It cannot be ruled out that the increases could be a biomarker of exposure since many of the lung cancer patients and most of the COPD patients were smokers. (C) 1998 Elsevier Science B.V. All rights reserved.