Table 2

Associations between cigarette smoking and rectal cancer risk in men and women

MenWomen
Cases (n)Controls (n)OR (95% CI)aCases (n)Controls (n)OR (95% CI)
Cigarette smoking
 Never2092971.02323281.0
 Former2292721.2 (0.9–1.6)931181.0 (0.7–1.5)
 Current (<5 yr)1181031.5 (1.1–2.1)67861.0 (0.7–1.5)
Age started smoking
 Never2092971.02323281.0
 ≤16 yr1531661.2 (0.9–1.7)50561.1 (0.7–1.7)
 17–20 yr1371331.5 (1.1–2.0)65831.1 (0.7–1.6)
 >20 yr60771.1 (0.8–1.7)46651.0 (0.6–1.5)
Years, Since stopping
 Never smoked2092971.02323281.0
 ≥15 yrs1702001.2 (0.9–1.6)66801.1 (0.7–1.6)
 5–14 yrs59721.1 (0.8–1.7)27381.0 (0.6–1.7)
 Current (<5 yr)1181031.5 (1.1–2.1)67861.0 (0.7–1.5)
Pack-yearsb
 Never2112981.02333291.0
 ≤201321941.0 (0.7–1.3)731080.9 (0.6–1.3)
 >202151791.7 (1.3–2.3)83921.2 (0.8–1.7)
Usual number cigarettes/day
 Never smoked2092981.02323281.0
 <202582761.3 (1.01–1.7)1301721.0 (0.7–1.4)
 ≥20921001.3 (0.9–1.8)30301.2 (0.7–2.2)
  • a Adjusted for age, physical activity level, alcohol intake, and body size.

  • b People who smoked <0.5 pack-years were classified as never having smoked, thus numbers across categories differ slightly.