Table 2. Smoking prevalence in lung cancer patients.

Variable	Smoke			Non-smoke
	Case number (%)	Smoking history (pack-year)		Case number (%)
Male	2,941 (80.2)			725 (19.8)
SCLC	363 (88.3)	44.6±27.8#		48 (11.7)
SCC	1,199 (89.5)	48.1±27.9#		140 (10.5)
ADC	1,167 (70.5)	36.6±25.5		488 (29.5)
Female	54 (2.7)			1,982 (97.3)
SCLC	6 (8.2)	22.2±18.2		67 (91.8)
SCC	16 (13.8)	31.0±15.6		100 (86.2)
ADC	31 (1.8)	23.3±28.3		1,739 (98.2)

^#, P<0.05 compared to ADC group. SCLC, small cell lung cancer; SCC, squamous cell carcinoma; ADC, adenocarcinoma.