. Author manuscript; available in PMC: 2014 Sep 2.

Published in final edited form as: Cancer Causes Control. 2014 Feb 1;25(4):479–489. doi: 10.1007/s10552-014-0350-1

Table 2.

Relative risks and 95 % CIs for endometrial carcinoma risk in relation to cigarette smoking among 110,304 women in the NIH–AARP Diet and Health Study, 1995–2006

	Non-cases n = 108,828		Endometrial carcinoma cases n = 1,476
	Person years	n (%)	n (%)	RR (95 % CI)^a
Smoking history
Never	470,730	45.0	772 (52.3)	1 (Ref)
Former	385,016	37.9	559 (37.9)	0.89 (0.80, 1.00)
Current	165,376	17.1	145 (9.8)	0.65 (0.55, 0.78)
Intensity
Former smokers
≤20 cigarettes/day	265,252	25.9	382 (25.9)	0.91 (0.81, 1.03)
>20 cigarettes/day	119,763	12.0	177 (12.0)	0.85 (0.72, 1.00)
Current smokers
≤20 cigarettes/day	122,013	12.4	102 (6.9)	0.64 (0.52, 0.78)
>20 cigarettes/day	43,662	4.6	43 (2.9)	0.70 (0.51, 0.95)
Time since quitting among former smokers^b
Cessation ≥10 years ago	273,108	32.1	422 (31.7)	0.95 (0.84, 1.07)
Cessation 5–9 years ago	69,172	8.3	93 (7.0)	0.81 (0.66, 1.01)
Cessation 1–4 years ago	42,735	5.2	44 (3.3)	0.65 (0.48, 0.89)

Adjusted for race (white, non-white), age at menarche (≤12, 13–14, ≥15), BMI (normal, overweight, obese), parity (nulliparous, 1–2, ≥3), oral contraceptive use (never, ever), age at menopause (premenopausal,<45, 45–49, 50–54, ≥55), menopausal hormone use (never, current, former), diabetes (never, ever), physical activity (never/rarely, 1–3 times/month, 1–2 times/week, 3–4 times/week, ≥5 times/week). Unknown was set as a separate category within each factor

Current smokers excluded