Table 2.
Characteristics of participants in the New England Case-Control Study (NECC) and the Nurses' Health Study (NHS) by history of regular genital talc use (at least once per week)
| Characteristic | NECC |
NHS§ |
||||
|---|---|---|---|---|---|---|
| No Regular Talc Use | Regular Talc Use | P‖ | No Regular Talc Use | Regular Talc Use | P‖ | |
| Mean value (standard deviation) | ||||||
| Age in years | 50 (13) | 53 (12) | <0.001 | 61 (8) | 62 (8) | 0.64 |
| Parity among parous women | 2.7 (1.4) | 2.7 (1.4) | 0.64 | 3.2 (1.4) | 3.3 (1.5) | 0.40 |
| Age at first birth among parous women | 25.0 (5.1) | 24.6 (4.9) | 0.22 | 25.0 (3.5) | 24.4 (3.0) | 0.03 |
| Duration oral contraceptive use (months)* | 58 (55) | 54 (54) | 0.24 | 53 (49) | 43 (42) | 0.08 |
| Body mass index (kg/m2) | 25.7 (5.7) | 27.0 (6.4) | <0.001 | 25.6 (4.6) | 26.2 (4.8) | 0.13 |
| Duration PMH use (months)* | 75 (74) | 78 (86) | 0.68 | 90 (74) | 83 (70) | 0.38 |
| Duration of lactation (months)† | 4.8 (10.8) | 4.3 (10.3) | 0.38 | 3.5 (2.5) | 3.2 (2.4) | 0.20 |
| Physical activity (hours/week) | 2.8 (5.0) | 2.4 (3.8) | 0.06 | 3.0 (2.3) | 3.1 (2.4) | 0.61 |
| Percent of study population | ||||||
| Parous | 74 | 75 | 0.75 | 93 | 92 | 0.81 |
| Ever user of oral contraceptives | 55 | 50 | 0.03 | 44 | 44 | 0.96 |
| History of tubal ligation | 16 | 16 | 0.97 | 22 | 13 | 0.008 |
| Postmenopause | 45 | 54 | <0.001 | 81 | 81 | 0.86 |
| Ever user of PMH | 17 | 26 | <0.001 | 66 | 64 | 0.73 |
| Ever smoker | 53 | 55 | 0.35 | 57 | 47 | 0.02 |
| Family history of ovarian cancer | 3.9 | 4.1 | 0.82 | 4.5 | 6.4 | 0.31 |
| Genotype frequencies, % | ||||||
| GSTM1 null | 52 | 52 | 0.72 | 51 | 49 | 0.66 |
| GSTT1 null | 21 | 22 | 0.59 | 22 | 17 | 0.15 |
| NAT2 slow acetylator‡ | 63 | 66 | 0.23 | 65 | 63 | 0.58 |
Duration of oral contraceptive use and postmenopausal hormone (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
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 (two to four years) prior to 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 chi-square test (binary variables)