Table 2.

Characteristics of participants in the NECC and the NHS by history of regular genital talc use (at least once a week)

CharacteristicNECC
NHS*
No regular talc useRegular talc usePNo regular talc useRegular talc useP
Mean (SD)
    Age (y)50 (13)53 (12)<0.00161 (8)62 (8)0.64
    Parity among parous women2.7 (1.4)2.7 (1.4)0.643.2 (1.4)3.3 (1.5)0.42
    Age at first birth among parous women25.0 (5.1)24.6 (4.9)0.2225.0 (3.5)24.4 (3.0)0.03
    Duration oral contraceptive use (mo)58 (55)54 (54)0.2453 (49)43 (42)0.08
    BMI (kg/m2)25.7 (5.7)27.0 (6.4)<0.00125.6 (4.6)26.2 (4.8)0.13
    Duration PMH use (mo)75 (74)78 (86)0.6890 (74)83 (70)0.38
    Duration of lactation (mo)§6.4 (12.1)5.8 (11.5)0.327.2 (10.2)6.3 (9.6)0.34
    Physical activity (h/wk)2.8 (5.0)2.4 (3.8)0.063.0 (2.3)3.1 (2.4)0.61
Percent of study population
    Parous74750.7593920.81
    Ever user of oral contraceptives55500.0344440.96
    History of tubal ligation16160.9722130.008
    Postmenopause4554<0.00181810.86
    Ever user of PMH1726<0.00166640.73
    Ever smoker53550.3557470.02
    Family history of ovarian cancer3.94.10.824.56.40.31
Genotype frequencies, %
    GSTM1 null52520.7251490.66
    GSTT1 null21220.5922170.15
    NAT2 slow acetylator63660.2365630.58
  • * 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 ttest (continuous variables) or a χ2 test (binary variables).

  • 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.