Table 2.
Studied relation | Reference | Type | Level of evidence | Material | Main findings | Relative risk (95% confidence interval) |
---|---|---|---|---|---|---|
Use of COC in relation to risk of epithelial ovarian cancer | Beral et al. [2008] | Meta-analysis | 2 | 23,257 cases 87,303 controls | • Decreased risk in COC ever users | 0.73 (0.70–0.76) |
• A more pronounced effect by duration of use | ||||||
Havrilesky et al. [2013] | Systematic review/meta-analysis | 657,055 women, 3,981,072 women years | • The protective effect lasts at least 30 years after use | 0.73 (0.66–0.81) | ||
Hannaford et al. [2007] | Prospective cohort | 2 | 46,000 women 744,000 women years | • Decreased risk in COC ever-users | 0.54 (0.40–0.71) | |
• A more pronounced effect by duration of use | ||||||
Vessey and Painter [2006] | Prospective cohort | 17,032 women, 540,000 women years | • The protective effect lasts at least 15–20 years | 0.5 (0.3–0.7) | ||
Use of COC in relation to endometrial cancer risk | Gierisch et al. [2013] | Systematic review/meta-analysis | 2 | 308,198 women | • Risk reduction among COC ever-users | 0.57 (0.43–0.77) |
• The effect lasts at least 20 years | ||||||
Use of COC in relation to colorectal cancer risk | Gierisch et al. [2013] | Systematic review/meta-analysis | 2 | 2,969,189 women years | • Risk reduction in COC ever-users | 0.86 (0.79–0.95) |
• Big variation between studies | ||||||
• No established relation between duration of use and effect | ||||||
Use of COC in relation to breast cancer risk | Gierisch et al. [2013] | Systematic review/meta-analysis | 2 | 317,341 women | • Small increase in risk during current use | 1.08 (1.00–1.17) |
• The increased risk declines and disappears 10 years after cessation | ||||||
Collaborative Group on Hormonal Factors in Breast Cancer [1996] | Systematic review/meta-analysis | 2 | 53,297 cases 100,239 controls | • The increased risk is highest among young users | 1.24 (1.15–1.33) | |
Use of COC in relation to cervical cancer risk | Appleby et al. [2007] | Systematic review/meta-analysis | 2 | 16,573 cases 35,509 controls | • Increased risk in current users | ≥5 year 1.9 (1.69–2.13) |
• The increased risk declines and disappears 10 years after cessation | ||||||
Longatto-Filho et al. [2011] | Prospective cohort | 2 | 12,114 women | • Presence of Hr-HPV was related to risk | No independent increased risk in COC usersNo trend if used <5 years; use 5–9 years: 2.82 (1.46–5.42); use >10 years 4.03(2.09–8.02) | |
Gierisch et al. [2013] | Systematic review/heterogeneity made meta-analysis impossible; pooled data from study of good quality | 2 | 1561 cases 1916 controls | • Increased risk only in Hr-HPV positive women |
Hr-HPV, high-risk human papillomavirus