Table 4.
Invasive ovarian cancer or borderline ovarian tumor risk for ART vs non-ART treatment within risk factor subgroups, excluding first year of follow-up
| Ovarian tumor risk factors | Invasive ovarian cancer |
Borderline ovarian tumor |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ART group |
Non-ART group |
Adj. HR for ART vs non-ART (95% CI)b | P c | ART group |
Non-ART group |
Adj. HR for ART vs non-ART (95% CI)b | P c | |||||
| No. of ovarian cancersa | No. of womena | No. of ovarian cancersa | No. of womena | No. of ovarian tumorsa | No. of womena | No. of ovarian tumorsa | No. of womena | |||||
| Parity | ||||||||||||
| Nulliparous | 60 | 10 787 | 18 | 2508 | 0.93 (0.55 to 1.58) | 38 | 10 787 | 2 | 2508 | 5.54 (1.33 to 22.99) | ||
| Parous | 55 | 19 665 | 18 | 7323 | 1.30 (0.76 to 2.22) | .38 | 41 | 19 665 | 15 | 7323 | 1.19 (0.66 to 2.16) | .05 |
| Start yeard | ||||||||||||
| 1983-1989 | 9 | 1818 | 16 | 3040 | 0.87 (0.38 to 1.99) | 11 | 1818 | 8 | 3040 | 2.25 (0.90 to 5.63) | ||
| 1990-2000 | 106 | 28 747 | 21 | 6932 | 1.09 (0.68 to 1.75) | .64 | 68 | 28 747 | 9 | 6932 | 1.91 (0.95 to 3.85) | .78 |
| Time since 1st ART treatment or 1st visit to the gynecologist, y | ||||||||||||
| <10 | 20 | 29 958 | 8 | 9504 | 0.65 (0.29 to 1.49) | 24 | 29 958 | 3 | 9504 | 2.40 (0.72 to 7.99) | ||
| 10-19 | 65 | 28 996 | 14 | 9654 | 1.27 (0.71 to 2.26) | .20 | 40 | 28 996 | 8 | 9654 | 1.73 (0.80 to 3.72) | .63 |
| ≥20 | 30 | 22 440 | 15 | 8136 | 1.07 (0.57 to 2.02) | .35 | 15 | 22 440 | 6 | 8136 | 1.44 (0.56 to 3.74) | .50 |
| Age at 1st ART treatment or 1st visit to the gynecologist, y | ||||||||||||
| <35 | 53 | 20 438 | 26 | 7697 | 0.81 (0.50 to 1.31) | 57 | 20 438 | 12 | 7697 | 2.18 (1.16 to 4.10) | ||
| ≥35 | 62 | 10 127 | 11 | 2275 | 1.48 (0.76 to 2.85) | .18 | 22 | 10 127 | 5 | 2275 | 1.16 (0.44 to 3.08) | .29 |
| Attained age, ye | ||||||||||||
| <50 | 41 | 30 565 | 21 | 9972 | 0.62 (0.36 to 1.05) | 47 | 30 565 | 8 | 9972 | 2.08 (0.98 to 4.42) | ||
| ≥50 | 74 | 25 060 | 16 | 8243 | 1.76 (1.01 to 3.07) | .01 | 32 | 25 060 | 9 | 8243 | 1.42 (0.67 to 2.99) | .48 |
Not all numbers add up to 100%, because of missing values. Adj. HR = adjusted hazard ratio; ART = assisted reproductive technology; CI = confidence interval.
Cox regression analyses: models with age (in years) as time scale and adjusted for parity (and additionally for tubal subfertility in borderline ovarian tumor analysis). Analyses includes 4537 women, 30 565 ART-treated women, and 9972 non-ART–treated women.
P of interaction terms.
ART treatment regimens before 1990 included gonadotropins with or without clomiphene. After 1989, the most often used ART treatment regimen consisted of gonadotropins in combination with gonadotrophin-releasing hormone agonists.
Analyses for attained age younger than 50 years comprise all person-years of women until their 50th birthday or date of any first cancer diagnosis, date of death, date of completeness of cancer registry (July 1, 2018), date of bilateral oophorectomy, or date of questionnaire completion for women who refused linkage with the Netherlands Cancer Registry, whichever came first. Analyses for attained age 50 years or older comprise only person-years of women who were 50 years or older at end of follow-up, starting at their 50th birthday, until date of any first cancer diagnosis, date of death, date of completeness of cancer registry (July 1, 2018), date of bilateral oophorectomy, or date of questionnaire completion for women who refused linkage with the Netherlands Cancer Registry, whichever came first.