Table 2.

Geometric means of 8-epi-prostaglandin F_2α (8-epiPGF_2α) in lung cancer cases and control subjects by smoking status, The Shanghai Cohort Study 1986–2013

Subject group	Cases		Controls		P for cases versus controls
	N	8-epiPGF2αa (pg/mg creatinine)	N	8-epiPGF2αa (pg/mg creatinine)
Total subjects	610	456 (434–479)	610	402 (382–422)	<0.001
By smoking status
Never smokers	116	248 (226–273)	116	254 (231–280)	0.743
Former smokers	58	293 (256–335)	58	222 (194–255)	0.005
Current smokers	436	573 (545–602)	436	488 (464–512)	<0.001
P for current versus never smokers		<0.001		<0.001	P for interaction = 0.019†
P for current versus former smokers		<0.001		<0.001
P for former versus never smokers		0.113		0.051

^aGeometric means (95% confidence intervals) and P values were derived from the two-way analysis of variance with log (8-epiPGF_2α) as dependent variable and lung cancer status and smoking status as the two main factors with the following covariates: age, year of biospecimen collection, neighborhood of residence at baseline, level of education and body mass index (kg/m²).

^†Two-sided P for interaction between smoking status (current versus never) and lung cancer status on log (8-epiPGF_2α).