Is it useful to combine sputum cytology and low-dose spiral computed tomography for early detection of lung cancer in formerly asbestos-exposed power industry workers?

Table 1 Asbestos exposure and other risk factors in the study group (n =187)

	Mean	SD	Range
Age (years)	65.8	5.8	46 – 78
Time since first exposure (years)	40.4	7.8	26 – 60
Duration of asbestos exposure (years)	29.5	7.7	15 – 49
Pack years	44.7	47.9	0 – 118