LUNG CANCER INCIDENCE AND SURVIVAL IN CHROMIUM EXPOSED INDIVIDUALS WITH RESPECT TO EXPRESSION OF ANTI-APOPTOTIC PROTEIN SURVIVIN AND TUMOR SUPPRESSOR P53 PROTEIN

Objective: Workers chronically exposed to hexavalent chromium have elevated risk of lung cancer. Our study investigates the incidence of lung cancer types, age at onset of the disease, and survival time among chromium exposed workers with respect to the expression of anti-apoptotic p53 and pro-apoptotic survivin proteins. Material and methods: 67 chromium exposed workers and 104 male controls diagnosed with lung cancer were analyzed. The mean exposure time among workers was 16.7 +/- 10.0(SD) years (range 1- 41 years). To investigate the possible regulation of survivin by p53 we examined the expression of both proteins using immohistochemical visualization. Results: Chromium exposure significantly decreases the age of onset of the disease by 3.5 years (62.2 +/- 9.1 in the exposed group vs. 65.7 +/- 10.5 years in controls; P=0.018). Small cell lung carcinoma (SCLC) amounted for 25.4% of all cases in chromium exposed workers and for 16.3% in non-exposed individuals. The mean survival time in the exposed group was 9.0 +/- 12.7 vs. 12.1 +/- 21.9 months in controls, but this difference was not significant. Survivin was predominantly expressed in both cell nucleus and cytoplasm, whereas p53 was expressed in the nucleus. There was a negative correlation between survivin and p53 expression. A decreased intensity of expression and fewer cells positive for survivin was detected in SCLC compared with other types of lung cancer. p53 was expressed in 94.1% and survivin in 79.6% of the samples analyzed. Conclusion: The study calls attention to decreased expression of survivin, as opposed to p53, in small cell lung carcinoma.