Hormonal and reproductive factors and reduction in the risk of colorectal cancer

Association of Hormonal Contraceptive Use With Adverse Health Outcomes: An Umbrella Review of Meta-analyses of Randomized Clinical Trials and Cohort Studies

IMPORTANCE

Meta-analyses have reported conflicting data on the safety of hormonal contraception, but the quality of evidence for the associations between hormonal contraceptive use and adverse health outcomes has not been quantified in aggregate.

OBJECTIVE

To grade the evidence from meta-analyses of randomized clinical trials (RCTs) and cohort studies that assessed the associations between hormonal contraceptive use and adverse health outcomes among women.

DATA SOURCES

MEDLINE, Embase, and the Cochrane Database of Systematic Reviews were searched from database inception to August 2020. Search terms included hormonal contraception, contraceptive agents, progesterone, desogestrel, norethindrone, megestrol, algestone, norprogesterones, and levonorgestrel combined with terms such as systematic review or meta-analysis.

EVIDENCE REVIEW

The methodological quality of each meta-analysis was graded using the Assessment of Multiple Systematic Reviews, version 2, which rated quality as critically low, low, moderate, or high. The Grading of Recommendation, Assessment, Development and Evaluations approach was used to assess the certainty of evidence in meta-analyses of RCTs, with evidence graded as very low, low, moderate, or high. Evidence of associations from meta-analyses of cohort studies was ranked according to established criteria as nonsignificant, weak, suggestive, highly suggestive, or convincing.

RESULTS

A total of 2996 records were screened; of those, 310 full-text articles were assessed for eligibility, and 58 articles (13 meta-analyses of RCTs and 45 meta-analyses of cohort studies) were selected for evidence synthesis. Sixty associations were described in meta-analyses of RCTs, and 96 associations were described in meta-analyses of cohort studies. Among meta-analyses of RCTs, 14 of the 60 associations were nominally statistically significant (P ≤ .05); no associations between hormonal contraceptive use and adverse outcomes were supported by high-quality evidence. The association between the use of a levonorgestrel-releasing intrauterine system and reductions in endometrial polyps associated with tamoxifen use (odds ratio [OR], 0.22; 95% CI, 0.13-0.38) was graded as having high-quality evidence, and this evidence ranking was retained in the subgroup analysis. Among meta-analyses of cohort studies, 40 of the 96 associations were nominally statistically significant; however, no associations between hormonal contraceptive use and adverse outcomes were supported by convincing evidence in the primary and subgroup analyses. The risk of venous thromboembolism among those using vs not using oral contraception (OR, 2.42; 95% CI, 1.76-3.32) was initially supported by highly suggestive evidence, but this evidence was downgraded to weak in the sensitivity analysis.

CONCLUSIONS AND RELEVANCE

The results of this umbrella review supported preexisting understandings of the risks and benefits associated with hormonal contraceptive use. Overall, the associations between hormonal contraceptive use and cardiovascular risk, cancer risk, and other major adverse health outcomes were not supported by high-quality evidence.

Impact of menopausal hormone therapy on colorectal cancer risk-A systematic review

Colorectal cancer (CRC) is the second most frequently diagnosed cancer in females worldwide. Menopausal hormone therapy (MHT) has been proposed as a potential protective factor for the development of CRC. Yet, the available evidence is controversial. Thus, we aimed at summarizing the current evidence on the effect of MHT on CRC through a systematic review. A systematic literature search identified 1001 potentially relevant articles, out of which 57 original studies and nine meta-analyses were deemed eligible for the final synthesis. The evidence synthesis showed the following: (1) MHT showed a heterogeneity in findings for CRC risk with a slight tendency to a neutral or protective effect; (2) MHT effect was either neutral or protective on colorectal adenoma; (3) MHT had no impact on tumour grade, subsite and histologic types; (4) MHT was not associated with CRC mortality; and (5) MHT showed heterogeneous effects on CRC stage and invasiveness, respectively. In summary, despite some evidence pointing towards a protective effect of MHT on CRC, MHT is currently not recommended for primary CRC prevention by international guidelines due to several important, potentially harmful effects.