. 2002 Mar 2;120(2):38–44. doi: 10.1590/S1516-31802002000200003

Table 7. Joint effect on lung cancer risk of smoking (2 strata) and cancer among first-degree relatives (2 strata).

Smoking (pack-years)	Cancer in relatives¹	Cases (n = 334)	Controls (n = 578)	OR² (95% CI)
0 – 20	No³	67	250	1.00
	Yes	15	71	0.79 (0.42 – 1.47)
≥ 21	No	163	179	3.53 (2.49 – 5.01)
	Yes	76	52	5.29 (3.37 – 8.30)

Any cancer in parents and siblings

Odds ratio adjusted for age and socioeconomic status (four levels)

Reference category.