Table 3.
Invasive ovarian cancer risk according to fertility treatment characteristics, excluding the first year of follow-up
| Fertility treatment characteristics | No. of ovarian cancers | No. of women | Adj. HR (95% CI)a |
|---|---|---|---|
| ART exposure | |||
| Non-ART | 37 | 9972 | 1 (Referent) |
| ART | 115 | 30 565 | 1.02 (0.70 to 1.50) |
| Total No. of ART cycles | |||
| 0 | 37 | 9972 | 1 (Referent) |
| 1-2 | 50 | 12 474 | 1.18 (0.76 to 1.82) |
| 3-4 | 39 | 11 586 | 0.87 (0.55 to 1.39) |
| ≥5 | 26 | 6505 | 1.01 (0.61 to 1.68) |
| Total No. of IUI and ART cyclesb | |||
| 0 | 19 | 4574 | 1 (Referent) |
| 1-2 | 27 | 9047 | 0.84 (0.46 to 1.53) |
| 3-4 | 36 | 8688 | 1.06 (0.60 to 1.87) |
| 5-6 | 11 | 4515 | 0.63 (0.30 to 1.35) |
| ≥7 | 35 | 8446 | 1.04 (0.59 to 1.84) |
| Missing | 24 | 5267 | 0.98 (0.53 to 1.81) |
| Response at 1st ART cyclec,d | |||
| Normal response | 60 | 14 943 | 1 (Referent) |
| Poor response | 14 | 4340 | 0.60 (0.33 to 1.07) |
| Missing | 41 | 11 282 | 0.92 (0.62 to 1.37) |
| OHSSd,e | |||
| Never | 111 | 29 602 | 1 (Referent) |
| Ever | 4 | 963 | 1.40 (0.52 to 3.81) |
| Clomiphene used | |||
| Never | 33 | 9712 | 1 (Referent) |
| Ever | 25 | 6515 | 0.93 (0.55 to 1.57) |
| Missing | 57 | 14 338 | 0.98 (0.63 to 1.50) |
| Main subfertility diagnosisf | |||
| Male factor | 38 | 11 572 | 1 (Referent) |
| Tubal factor | 51 | 12 952 | 0.98 (0.64 to 1.50) |
| Unexplained or other factor | 63 | 16 013 | 1.08 (0.72 to 1.61) |
| Endometriosisf,g | |||
| No | 132 | 36 936 | 1 (Referent) |
| Yes | 20 | 3601 | 1.47 (0.92 to 2.36) |
| Parityf | |||
| Nulliparous | 78 | 13 295 | 1 (Referent) |
| Parous | 73 | 26 988 | 0.54 (0.39 to 0.75) |
Analyses include 40 537 women, 30 565 ART treated women, and 9972 non-ART–treated women. Each variable was analyzed in a separate model. All analyses are adjusted for age at start of treatment or visit to gynecologist and parity. Adj. HR = adjusted hazard ratio; ART = assisted reproductive technology; CI = confidence interval; IUI = intrauterine insemination; OHSS = ovarian hyperstimulation syndrome.
Includes stimulated and nonstimulated IUI cycles. Based on information from medical records if available and on information from questionnaires if no medical record information was available. Women with missing data about IUI cycles and with a tubal cause of subfertility were categorized in the 0 IUI cycles category.
Poor response includes canceled first cycles because of anticipated poor response and less than 4 oocytes; normal response includes 4 or more oocytes collected in first cycle.
Among 30 565 ART-treated women only; 115 invasive ovarian cancer cases.
OHSS includes women who had had no ovum pick-up because of (anticipated) OHSS.
Additionally adjusted for ART exposure (yes/no).
Histologically proven endometriosis, based on information from The Nationwide Network and Registry of Histo- and Cytopathology in the Netherlands (PALGA).