Objective To systematically assess literature regarding the relationship between ovulation induction and the risk of ovarian cancer. Methods We searched MEDLINE, EMbase, The Cochrane Library, CBM and CNKI (from inception to Feb, 2012). Cohort or case-control studies were identified according to the inclusion and exclusion criteria. Then the quality of the included studies was assessed, and the data was extracted. Meta-analysis was performed by RevMan 5.0 software. The incorporated RR (relative risk) and 95%CI (confidence interval) of the included cohort studies and incorporated OR (odds ratio) and 95%CI of case-control studies were calculated, respectively. Results Four cohort studies and four case-control studies were included. Result of meta-analysis on cohort studies showed ovulation induction didn’t increase the risk of ovarian cancer (RR=1.07, 95%CI 0.81 to 1.42, P=0.63). Besides, result of meta-analysis on case-control studies showed ovulation induction was not associated with the incidence of ovarian cancer (OR=1.28, 95%CI 0.78 to 2.08, P=0.33). But the risk of borderline ovarian tumors increased when compared with general population controls (OR=1.71, 95%CI 1.05 to 2.79, P=0.03). Conclusion Ovulation induction does not increase the risk of ovarian cancer, but may relate to the incidence of borderline ovarian cancer. However, more high-quality studies, especially perspective cohort studies are required because of the limited quantity of the included studies.
Objective To evaluate the effectiveness and safety of aromatase inhibitors in ovulation induction for women with unexplained infertility. Methods The databases such as CNKI (1994 to June 2011), WanFang Data (1982 to June 2011), PubMed (1966 to June 2011) and The Cochrane Library (Issue 6, 2011) were searched to collect randomized controlled trials (RCTs) and quasi-randomized controlled trials (quasi-RCTs) for the comparison between aromatase inhibitors (AIs) and clomiphene citrate (CC). The quality of the retrieved trials was critically appraised and meta-analyses were conducted using RevMan 5.0.1 software. Results Nine studies were included; all of them were published in English. The results of meta-analyses showed there were no significant differences between AIs and CC in the pregnancy rate (RR=1.02, 95%CI 0.71 to 1.47), miscarriage rate (RR=1.00 95%CI 0.61 to 1.63), multiple pregnancy rate (RD= –0.02, 95%CI –0.07 to 0.03), and incidence rate of adverse events (RD=0.00, 95%CI –0.01 to 0.01); there were still no significant differences between the AIs+gonadotropin (Gn) group and the CC+Gn group in the pregnancy rate (RR=0.98, 95%CI 0.68 to 1.42), miscarriage rate (RR=1.23, 95%CI 0.70 to 2.15), multiple pregnancy rate (RD=0.00, 95%CI –0.10 to 0.10), and incidence rate of adverse events (RD=0.00, 95%CI –0.10 to 0.01). Conclusion Whether aromatase inhibitors can replace clomiphene citrate in ovulation induction for women with unexplained infertility is still an issue that has to be identified by performing well-designed large scale RCTs with longer follow-up duration.
Objective To assess the effectiveness of letrozole in ovulation induction treatment. Methods We searched CBMdisc (1979 to 2009), Wanfang (1994 to 2009), CNKI (1994 to 2009), VIP(1989 to 2009), PubMed (1997 to 2009), PML (1997 to 2009), FMJS(2000 to 2009) and 9 relevant journals to identify randomized controlled trails (RCTs) comparing letrozole with clomiphene citrate in ovulation induction treatment. The quality of the included trials was critically appraised. RevMan 4.2.7 software was used for statistical analyses. Results Ten RCTs involving 3100 patients were included, among which 5 RCTs were graded A, 4 were graded B, and 1 was graded C. Five RCTs showed that endometrial thickness at the time of human chorionic gonadotrophin (HCG) administration in the letrozole group was significantly higher than that in the clomiphene group. One RCT showed that endometrial thickness at the time of HCG administration in the letrozole group was significantly lower than that in the clomiphene group. Three RCTs showed no significant differences between the two groups. Four RCTs showed that the number of dominant follicle at the time of HCG administration in the letrozole group was signficantly lower than that in the clomiphene group. One RCT showed that the number of dominant follicle at the time of HCG administration in the letrozole group was significantly higher than that in the clomiphene group. Two RCTs showed no significant differences between the two groups. Compared with clomiphene citrate, the pregnancy rate in the letrozole monotherapy group was slightly lower at the RR 1.03 and 95%CI 0.82 to 1.29, pregnancy rate in the combination group was higher at RR 1.73 and 95%CI 1.37 to 2.18. The ovulation rate in the letrozole group was higher and no significant differences were found between the two groups at RR 1.23 and 95%CI 0.97 to 1.57. Conclusions There may be differences between letrozole and clomiphene citrate in ovulation induction treatment in terms of endometrial thickness, number of dominant follicle, ovulation rate, and pregnancy rate, but no significant differences. Letrozole can make up for the shortcomings of clinical clomiphene in ovulation induction and serve as an alternative. This conclusion needs to be further confirmed through more well-designed, multi-centered, large-sample RCTs.