Abstract
Background: While several studies have reported varying associations between tubal ligation and ovarian cancer, no recent meta‐analysis has been conducted. In addition, past meta‐analyses have not examined whether study factors, such as study design, or individual factors, such as age at procedure, modify the relationship between ovarian cancer and tubal ligation.
Methods: We sought to identify all English‐language articles in the PubMed database with quantitative data on the effect of tubal ligation and ovarian cancer using the keywords “ovarian cancer” and “tubal ligation” or “tubal sterilization”. We identified 21 articles which provided estimates of the risk of ovarian cancer in relation to tubal ligation and six articles which reported stratum‐specific estimates of ovarian cancer risk by age at and years since tubal ligation. The summary relative risk (RR) estimate and the 95% confidence interval (CI) for the summary estimate were calculated using a random‐effects model. Tests for homogeneity were used to evaluate the consistency of findings among studies, and Begg's and Egger's tests were used to assess publication bias.
Results: The RRs for ovarian cancer comparing women who had a tubal ligation to those who did not ranged from 0.20 to 2.40 across the studies. The summary RR was 0.68 (95% CI: 0.62–0.75), demonstrating a statistically significant protective effect of tubal ligation on ovarian cancer. We found no evidence of heterogeneity by study design (e.g., cohort versus case‐control) or residence of participants (United States vs. non‐United States) as well as no evidence of publication bias. In secondary analyses based on four studies, we did not detect a difference in the risk of ovarian cancer between women who had a tubal ligation less than 20 years ago versus 20 or more years ago (p for heterogeneity = 0.65). Similarly, we did not detect effect modification by age (<35 years of age, >35 years of age) at tubal ligation (p for heterogeneity = 0.92). Though data were insufficient to calculate summary RRs by histologic subtype, a qualitative examination of study results demonstrated a stronger protective effect of tubal ligation for endometroid tumors.
Conclusions: Observational epidemiologic evidence strongly suggests that there is a decreased risk of ovarian cancer among women who have had a tubal ligation. We found a 30 percent reduction in ovarian cancer among women who had ever had a tubal ligation compared to women who have never had a tubal ligation. This estimate did not vary by study design or residence of participants. In addition, we did not detect any effect modification by age at tubal ligation or years since tubal ligation. While there is some evidence that the effect of tubal ligation varies by histologic subtype, further research is needed in this area.
Citation Information: Cancer Prev Res 2010;3(1 Suppl):B134.
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