Table 1.

Characteristics of ovarian cancer cases and controls in the NECC and the NHS

CharacteristicNECC
NHS*
CasesControlsPCasesControlsP
N1,1751,202210600
Mean (SD)
    Age (y)51 (13)51 (13)0.3762 (8)62 (8)0.93
    Parity among parous women2.5 (1.3)2.8 (1.5)<0.0013.0 (1.3)3.4 (1.5)0.004
    Duration oral contraceptive use (mo)§52 (54)61 (55)0.00646 (42)53 (49)0.22
    BMI (kg/m2)26.3 (6.3)25.7 (5.5)0.0225.7 (5.0)25.7 (4.5)0.94
    Duration PMH use (mo)§78 (86)74 (71)0.6496 (84)85 (68)0.18
    Duration of lactation (mo)5.0 (10.0)7.3 (13.2)<0.0016.0 (10.3)7.2 (9.7)0.17
Percent of study population
    Parous6881<0.00189930.05
    Ever user of oral contraceptives4860<0.00142450.57
    History of tubal ligation14180.00714210.02
    Ever user of PMH17200.1471630.02
    Family history of ovarian cancer5.12.80.0049.13.70.002
    Any history of genital talc use29240.00340390.79
    Regular genital talc use (once a week or more)2720<0.00129240.15
    Daily genital talc use16120.00618130.08
Genotype frequencies, %
    GSTM1 null51530.4248520.36
    GSTT1 null21220.8519210.45
    NAT2 slow acetylator63640.7459670.05
  • * In the NHS, duration of lactation was collected in 1986, family history of ovarian cancer was first collected in 1992, and history of genital talc use was collected in 1982; for variables collected on multiple questionnaires, the value from two cycles (2-4 y) before the date of diagnosis for each case was used for the case and their matched controls.

  • P values calculated using proc t test (continuous variables) or a χ2 test (binary variables).

  • Cases and controls in each study population were matched (NHS) or frequency-matched (NECC) on age.

  • § Duration of oral contraceptive use and PMH use among ever users.

  • Total duration among parous women.

  • NAT2 acetylation genotype based on analysis of three single nucleotide polymorphisms, I114T, R197Q, and G286E.