Table 5.

Incidence of invasive ovarian cancer and borderline ovarian tumor according to successful (childbirth) and unsuccessful (no childbirth) ART cycles, excluding the first year of follow-up

Successful/unsuccessful ART cycles	Invasive ovarian cancer				Borderline ovarian tumor
	No. of cancers	No. of women	Adj. HR (95% CI)a	P b	No. of tumors	No. of women	Adj. HR (95% CI)a	P b
Successful ART cycle(s)c
0 cycles	75	13 272	1 (Referent)		42	13 272	1 (Referent)
1 cycle	28	9743	0.54 (0.34 to 0.87)		23	9743	0.79 (0.45 to 1.39)
≥2 cycles	12	7550	0.37 (0.18 to 0.73)	.001	14	7550	0.67 (0.33 to 1.35)	.21
Unsuccessful ART cycle(s)c
0 cycles	12	6005	1 (Referent)		13	6005	1 (Referent)
1 ART cycle	24	5761	1.20 (0.57 to 2.53)		13	5761	0.87 (0.39 to 1.95)
2 ART cycles	26	5323	1.29 (0.61 to 2.75)		12	5323	0.79 (0.34 to 1.84)
3 ART cycles	21	5505	0.83 (0.37 to 1.87)		16	5505	0.94 (0.41 to 2.17)
≥4 ART cycles	32	7971	0.88 (0.41 to 1.88)	.25	25	7971	0.92 (0.42 to 2.00)	.69

^aCox regression analyses incorporating the numbers of successful and unsuccessful ART cycles as separate time-dependent variables into 1 model, using age (in years) as time scale. Analyses are adjusted for age at start treatment or first visit to gynecologist and number of spontaneous births (for borderline tumors additionally for tubal subfertility). Analyses include 30 452 ART-treated women. Adj. HR= adjusted hazard ratio; ART = assisted reproductive technology; CI = confidence interval.

^b P value of trend test. Trend tests were based on the P value of the category-specific mean as a continuous variable.

^cSuccessful ART cycles were defined as cycles leading to the birth of a child, unsuccessful cycles as ART cycles that did not result in a childbirth.