Table 1.

Characteristics of the NCCCS I and NCCCS II study populations by case status (N = 3,676)

CharacteristicsNCCCS I
NCCCS II
Cases (n = 637)Controls (n = 1,044)Cases (n = 1,007)Controls (n = 988)
Diabetes133 (20.88)185 (17.72)183 (18.17)158 (15.99)
African American race290 (45.53)434 (41.57)255 (25.32)168 (17.00)
Mean age (SD), y63.69 (10.07)66.06 (9.49)61.88 (10.22)63.86 (9.77)
Sex, female307 (48.19)529 (50.67)436 (43.30)400 (40.49)
Smoking status*
    Current105 (16.56)187 (17.91)182 (18.09)141 (14.36)
    Former277 (43.69)412 (39.46)447 (44.43)463 (47.15)
    Never252 (39.75)445 (42.62)337 (37.48)378 (38.49)
Family history*,126 (19.81)102 (9.83)119 (12.93)97 (10.40)
Highest level of education*
    High school degree or less409 (64.21)600 (57.53)543 (53.92)426 (43.12)
    Some college122 (19.15)224 (21.48)245 (24.33)254 (25. 71)
    College degree or more106 (16.64)219 (21.00)219 (21.75)308 (31.17)
NSAID use*,
    Never73 (11.46)74 (7.09)244 (24.23)167 (16.92)
    Occasional254 (39.87)316 (30.27)440 (43.69)410 (41.54)
    Frequent310 (48.67)654 (62.64)323 (32.08)410 (41.54)
Colorectal cancer screening,§277 (43.49)632 (60.54)388 (39.31)684 (70.23)
BMI*
    Normal (<25 kg/m2)142 (22.87)278 (27.63)226 (23.32)285 (29.69)
    Overweight (25-29.9 kg/m2)255 (41.06)401 (39.86)350 (36.12)382 (39.79)
    Obese (≥30 kg/m2)224 (36.07)327 (32.50)393 (36.12)293 (30.52)
Mean energy intake (SD), kcal/d*2,041.69 (862.75)1,795.16 (687.83)2,447.08 (1,228.20)2,209.92 (967.80)
Mean calcium intake (SD), mg/d*791.22 (469.69)850.37 (495.49)844.80 (418.18)844.93 (406.27)
  • * In the NCCCS I, data were missing for smoking (n = 3), family history (n = 7), education (n = 1), BMI (n = 54), energy intake (n = 9), and calcium intake (n = 53); in the NCCCS II, data were missing for smoking (n = 7), family history (n = 142), NSAID use (n = 1), screening (n = 34), BMI (n = 66), energy intake (n = 16), and calcium intake (n = 16).

  • Family history of colorectal cancer was defined as a first-degree relative having been diagnosed with colorectal cancer.

  • NSAID use was defined as “frequent” for use of NSAIDs at least 15 times/mo, “occasional” for use <15 times/mo, and “never” for no use.

  • § Colorectal cancer screening was defined as having undergone one of the following tests for screening purposes: colonoscopy, sigmoidoscopy, barium enema, or fecal occult blood test.