Risk of endometrial cancer in women treated with ovary-stimulating drugs for subfertility.

BACKGROUND: Medical treatment for subfertility principally involves the use of ovary-stimulating agents, including selective oestrogen receptor modulators (SERMs), such as clomiphene citrate, gonadotropins, gonadotropin-releasing hormone (GnRH) agonists and antagonists, as well as human chorionic gonadotropin. Ovary-stimulating drugs may act directly or indirectly upon the endometrium (lining of the womb). Nulliparity and some causes of subfertility are recognized as risk factors for endometrial cancer. OBJECTIVES: To evaluate the association between the use of ovary-stimulating drugs for the treatment of subfertility and the risk of endometrial cancer. SEARCH METHODS: A search was performed in CENTRAL, MEDLINE (Ovid) and Embase (Ovid) databases up to July 2016, using a predefined search algorithm. A search in OpenGrey, ProQuest, ClinicalTrials.gov, ZETOC and reports of major conferences was also performed. We did not impose language and publication status restrictions. SELECTION CRITERIA: Cohort and case-control studies reporting on the association between endometrial cancer and exposure to ovary-stimulating drugs for subfertility in adult women were deemed eligible. DATA COLLECTION AND ANALYSIS: Study characteristics and findings were extracted by review authors independently working in pairs. Inconsistency between studies was quantified by estimating I2. Random-effects (RE) models were used to calculate pooled effect estimates. Separate analyses were performed, comparing treated subfertile women versus general population and/or unexposed subfertile women, to address the superimposition of subfertility as an independent risk factor for endometrial cancer. MAIN RESULTS: Nineteen studies were eligible for inclusion (1,937,880 participants). Overall, the quality of evidence was very low, due to serious risk of bias and indirectness (non-randomised studies (NRS), which was reflected on the GRADE assessment.Six eligible studies, including subfertile women, without a general population control group, found that exposure to any ovary-stimulating drug was not associated with an increased risk of endometrial cancer (RR 0.96, 95% CI 0.67 to 1.37; 156,774 participants; very low quality evidence). Fifteen eligible studies, using a general population as the control group, found an increased risk after exposure to any ovary-stimulating drug (RR 1.75, 95% CI 1.18 to 2.61; 1,762,829 participants; very low quality evidence).Five eligible studies, confined to subfertile women (92,849 participants), reported on exposure to clomiphene citrate; the pooled studies indicated a positive association ( RR 1.32; 95% CI 1.01 to 1.71; 88,618 participants; very low quality evidence), although only at high dosage (RR 1.69, 95% CI 1.07 to 2.68; two studies; 12,073 participants) and at a high number of cycles (RR 1.69, 95% CI 1.16 to 2.47; three studies; 13,757 participants). Four studies found an increased risk of endometrial cancer in subfertile women who required clomiphene citrate compared to a general population control group (RR 1.87, 95% CI 1.00 to 3.48; four studies, 19,614 participants; very low quality evidence). These data do not tell us whether the association is due to the underlying conditions requiring clomiphene or the treatment itself.Using unexposed subfertile women as controls, exposure to gonadotropins was associated with an increased risk of endometrial cancer (RR 1.55, 95% CI 1.03 to 2.34; four studies; 17,769 participants; very low quality evidence). The respective analysis of two studies (1595 participants) versus the general population found no difference in risk (RR 2.12, 95% CI 0.79 to 5.64: very low quality evidence).Exposure to a combination of clomiphene citrate and gonadotropins, compared to unexposed subfertile women, produced no difference in risk of endometrial cancer (RR 1.18, 95% CI 0.57 to 2.44; two studies; 6345 participants; very low quality evidence). However, when compared to the general population, an increased risk was found , suggesting that the key factor might be subfertility, rather than treatment (RR 2.99, 95% CI 1.53 to 5.86; three studies; 7789 participants; very low quality evidence). AUTHORS' CONCLUSIONS: The synthesis of the currently available evidence does not allow us to draw robust conclusions, due to the very low quality of evidence. It seems that exposure to clomiphene citrate as an ovary-stimulating drug in subfertile women is associated with increased risk of endometrial cancer, especially at doses greater than 2000 mg and high (more than 7) number of cycles. This may largely be due to underlying risk factors in women who need treatment with clomiphene citrate, such as polycystic ovary syndrome, rather than exposure to the drug itself. The evidence regarding exposure to gonadotropins was inconclusive.

Risk for childhood leukemia associated with maternal and paternal age.

The role of reproductive factors, such as parental age, in the pathogenesis of childhood leukemias is being intensively examined; the results of individual studies are controversial. This meta-analysis aims to quantitatively synthesize the published data on the association between parental age and risk of two major distinct childhood leukemia types in the offspring. Eligible studies were identified and pooled relative risk (RR) estimates were calculated using random-effects models, separately for childhood acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Subgroup analyses were performed by study design, geographical region, adjustment factors; sensitivity analyses and meta-regression analyses were also undertaken. 77 studies (69 case-control and eight cohort) were deemed eligible. Older maternal and paternal age were associated with increased risk for childhood ALL (pooled RR = 1.05, 95 % CI 1.01-1.10; pooled RR = 1.04, 95 % CI 1.00-1.08, per 5 year increments, respectively). The association between maternal age and risk of childhood AML showed a U-shaped pattern, with symmetrically associated increased risk in the oldest (pooled RR = 1.23, 95 % CI 1.06-1.43) and the youngest (pooled RR = 1.23, 95 % CI 1.07-1.40) extremes. Lastly, only younger fathers were at increased risk of having a child with AML (pooled RR = 1.28, 95 % CI 1.04-1.59). In conclusion, maternal and paternal age represents a meaningful risk factor for childhood leukemia, albeit of different effect size by leukemia subtype. Genetic and socio-economic factors may underlie the observed associations. Well-adjusted studies, scheduled by large consortia, are anticipated to satisfactorily address methodological issues, whereas the potential underlying genetic mechanisms should be elucidated by basic research studies.

Circulating leptin levels and risk of colorectal cancer and adenoma: a case-control study and meta-analysis.

PURPOSE: Equivocal results regarding the role of leptin in colorectal cancer (CRC) and adenoma (CRA) have been reported. A case-control study investigating the association of leptin with CRC risk and clinicopathological characteristics along with meta-analysis of published data on both CRC and CRA were conducted. METHODS: Pubmed and Embase were searched for the meta-analysis, comprising 28 case-control studies amounting 3,614 CRC and 1,215 CRA cases, along with 5,220 controls. Meticulous contact with the authors of individual studies was undertaken for the provision of additional data. Pooling of standardized mean differences (SMD), relative risks (RR) and 95 % CI (random effects models), subgroup, sensitivity, and meta-regression analyses were conducted. RESULTS: The meta-analysis suggested positive association of serum leptin with CRA (RR, 95 % CI 1.35, 1.03 to +1.76), but not CRC either at the pooled analysis on SMDs or RRs (SMD, 95 % CI 0.18, -0.04 to +0.40; RR, 95 % CI 1.04, 0.65 to +1.65). Significant heterogeneity between studies on CRC as well as between studies on CRA providing SMD was noted. Subgroup, meta-regression and sensitivity analyses highlighted potential methodology-, design-, size- and quality-related effect modifiers. CONCLUSIONS: Meta-analysis of current evidence suggests positive association of serum leptin with CRA but not with CRC risk. Given the case-control nature of available studies, the limited number of studies on serum leptin and CRA, and the heterogeneity of CRC studies, carefully designed, prospective studies preferably reporting RRs adjusted for a variety of confounders may be warranted.

Serum adiponectin levels and tissue expression of adiponectin receptors are associated with risk, stage, and grade of colorectal cancer.

Adiponectin has been associated with colorectal cancer (CRC) risk. This study aims to investigate the association of both adiponectin and tissue expression of its receptors with CRC risk as well as clinicopathological characteristics, notably stage and grade. Determination of serum adiponectin and immunohistochemical expression of adiponectin receptors in adenocarcinoma/normal colorectal tissue was performed in samples from 104 newly diagnosed CRC patients and 208 age- and sex-matched controls. Multiple logistic regression odds ratios and 95% confidence intervals for CRC risk were derived, controlling for a series of covariates. Serum adiponectin was negatively associated with CRC risk (odds ratio, 0.72; confidence interval, 0.53-0.99) and also with tumor grade (P = .05). Expression of both adiponectin receptors was stronger in adenocarcinoma vs normal tissue (P = .001). AdipoR1 expression was negatively associated with nodal stage (P = .03); AdipoR2 expression was positively associated with tumor, node, metastasis stage (P = .01). Established positive associations with red meat consumption and diabetes, and negative associations with physical exercise and plant food consumption were confirmed along with a more than 60% higher risk associated with central obesity. Adiponectin levels and tissue expression of hormonal receptors seem to be associated not only with CRC risk but also with components of clinicopathological characteristics; given power limitations, these results should be interpreted with caution. The exact nature of the association and the underlying pathophysiological mechanisms need to be further examined in large prospective studies assessing adiponectin and its receptors as novel targets for exploring CRC growth.