Table 5.

Relative risk of different histological types of ovarian cancer associated with hormonal contraception (full cohort), by categories of hormonal contraception use

Histology and use category	No of person years	No of cancer events	Adjusted relative risk (95% CI)*
Epithelial ovarian cancer
Any epithelial ovarian cancer	—	902	—
Never use	8 150 250	566	1.00
Current or recent use	8 839 374	155	0.58 (0.47 to 0.70)
Former use	4 505 157	181	0.75 (0.62 to 0.91)
Clear cell epithelial ovarian cancer	—	61	—
Never use	8 150 250	41	1.00
Current or recent use	8 839 374	9	0.59 (0.28 to 1.27)
Former use	4 505 157	11	0.68 (0.32 to 1.41)
Endometrioid epithelial ovarian cancer	—	135	—
Never use	8 150 250	93	1.00
Current or recent use	8 839 374	21	0.58 (0.35 to 0.96)
Former use	4 505 157	21	0.64 (0.38 to 1.06)
Mucinous epithelial ovarian cancer	—	204	—
Never use	8 150 250	107	1.00
Current or recent use	8 839 374	45	0.65 (0.44 to 0.97)
Former use	4 505 157	52	0.96 (0.65 to 1.41)
Serous epithelial ovarian cancer	—	502	—
Never use	8 150 250	325	1.00
Current or recent use	8 839 374	80	0.55 (0.42 to 0.72)
Former use	4 505 157	97	0.72 (0.56 to 0.93)
Non-epithelial ovarian cancer
No of ovarian cancer events	—	73	—
Never use	8 150 250	33	1.00
Current or recent use	8 839 374	21	0.64 (0.34 to 1.20)
Former use	4 505 157	19	1.09 (0.57 to 2.08)
Malignant tumour not otherwise specified
No of ovarian cancer events	—	274	—
Never use	8 150 250	172	1.00
Current or recent use	8 839 374	58	0.57 (0.41 to 0.80)
Former use	4 505 157	44	0.73 (0.50 to 1.05)

^*Adjusted for calendar year, parity, age, education, tubal sterilisation, hysterectomy, endometriosis, polycystic ovary syndrome, and family history of breast or ovarian cancer.