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Table 1 Selected characteristics of the study population at enrollment, stratified by cohort, among 602,242 Norwegian men and women (1972–2003)

From: Smoking increases rectal cancer risk to the same extent in women as in men: results from a Norwegian cohort study

Characteristics Oslo study Ia(1972–1973) Norwegian counties study (1974–1987) 40 years cohort (1985–1999) CONOR (Cohort of Norway) (1994–2003) All (1974–2003)
  Men Men Women Men Women Men Women Men Women
Subjects 16,946 41,913 41,573 185,037 199,730 55,480 61,563 299,376 302,866
Person- years of follow-up 476,518 1, 058, 699 1,079, 213 2,424,435 2,595, 800 462,398 516,186 4,422, 049 4,191,200
Age at enrollment, mean, SD 45 ± 6 40 ± 7 40 ± 7 43 ± 5 43 ± 5 48 ± 14 48 ± 15 44 ± 8 44 ± 8
Age at rectal cancer diagnosis, mean, SD 66 ± 8 62 ± 8 63 ± 8 57 ± 10 55 ± 9 66 ± 11 66 ± 14 62 ± 10 59 ± 11
Year of birth, median, (Range) 1929(1925–1931) 1938(1932–1944) 1939(1932–1944) 1951(1948–1954) 1951(1948–1954) 1954(1940–1960) 1955(1941–1960) 1950(1944–1954) 1951(1946–1955)
Number of cases 286 366 281 504 426 180 133 1,336 840
Follow-up years, median, (Range) 32(24–33) 28(20–30) 30(20–31) 13(10–16) 13(10–16) 9(6–10) 9(6–10) 13(10–18) 12(9–17)
≥13 years of educationb, (%) 24 14 12 26 22 21 21 23 20
Body mass index (BMI), mean, (kg/m2) 25 25 24 26 24 26 25 26 25
Level of physical activity, heavyc (%) 20 31 11 35 21 38 28 34 21
Ever smokers (%) 79 74 54 66 61 62 56 67 59
Current smokers (%) 55 51 40 40 40 31 32 41 38
Former smokers (%) 24 23 14 26 21 31 24 26 21
  1. SD standard deviation, Range interquartile range. aIncluded only men. bNot at enrollment. cHeavy physical activity: Light sports or heavy gardening ≥ 4 hours per week, heavy exercise or daily competitive sports.