Table 2.

Cause-specific hazard ratios of risk factors for second primary lung cancer in the final proposed risk prediction model in the Multiethnic Cohort^a

Factors	No.	Cause-specific Cox hazards model
		HR (95% CI)	P b
Histology of IPLC
Squamous cell	1185	Referent
Large cell	2053	2.01 (0.88 to 4.57)	.01
Adenocarcinoma	163	1.15 (0.76 to 1.75)	.51
Small cell	624	0.79 (0.23 to 2.66)	.70
Non–small cell carcinoma, NOS	473	0.88 (0.30 to 2.57)	.82
Otherc	856	0.99 (0.52 to 1.89)	.97
Prior history of cancerd
No	3949	Referent
Yes	1405	1.44 (1.00 to 2.06)	.047
Met the 2013 USPSTF criteriae
No	3539	Referent
Yes	1815	1.74 (1.15 to 2.63)	.008
Smoking intensity, cigarettes per day	5354	1.01 (0.99 to 1.04)	.25
Surgery for IPLC
No	2525	Ref
Yes	3414	2.10 (1.23 to 3.59)	.007
Stage of IPLC
Early stagef	2254	Referent
Advanced stage	3100	0.48 (0.21 to 1.07)	.07
Stage of IPLC × Met the 2013 USPSTF Criteriae		0.28 (0.06 to 1.36)	.11

^aBased-on participants (n = 5354) with complete data for the variables in the proposed prediction model. CI = confidence interval; HR = hazard ratio; IPLC = initial primary lung cancer; NOS = not otherwise specified; USPSTF = US Preventive Services Task Force.

^b P value by 2-sided Wald for the cause-specific Cox hazards model.

^cClassification of “other” histology based on International Classification of Diseases–O-3 codes including 8000, 8001, 8010, 8020, 8022, 8030-8033, 8200, 8240, 8244, 8246, 8249, 8560, 8800, 8810, 8890, and 8980; all confirmed lung cancer diagnosis.

^dHistory of cancer, other than lung, before the time of IPLC diagnosis.

^eAged 55-80 years, smoked ≥30 pack-years of smoking, and ≤15 years since cessation.

^fDisease extent was defined using Surveillance, Epidemiology, and End Results Extent of Disease as local and regional for early stage and distant for advanced stage.