Table 3.

Relative lifetime number of ovulatory cycles and ovarian cancer risk

Lifetime number of ovulatory cycles*
P trend
Low, n (%)Medium, n (%)High, n (%)
Controls223 (33)224 (33)227 (34)
All cases145 (24)182 (30)274 (46)<0.0001
    OR (95% CI)1.25 (0.94-1.67)1.87 (1.42-2.47)1.88 (1.42-2.47)
Serous borderline cases34 (42)24 (30)23 (28)0.54
    OR (95% CI)1.000.80 (0.45-1.42)0.84 (0.47-1.52)
Serous invasive cases60 (24)65 (26)121 (49)0.0005
    OR (95% CI)1.001.01 (0.67-1.51)1.84 (1.27-2.65)
Mucinous cases12 (22)24 (44)19 (35)0.10
    OR (95% CI)1.002.19 (1.06-4.52)1.93 (0.89-4.19)
Endometrioid cases18 (18)22 (22)58 (59)<0.0001
    OR (95% CI)1.001.33 (0.69-2.56)3.92 (2.19-7.04)
Clear cell cases16 (20)28 (35)36 (45)0.002
    OR (95% CI)1.001.91 (0.99-3.66)2.71 (1.42-5.17)
Other cases5 (12)19 (46)17 (42)0.04
    OR (95% CI)1.003.66 (1.34-10.01)3.24 (1.17-8.99)
  • * There are 114 women missing estimated lifetime number of ovulatory cycles because they reported that their menstrual cycles were never regular.

  • Adjusted for reference age (continuous), study center (Massachusetts or New Hampshire), cesarean section, tubal ligation, and hysterectomy.