Intrauterine device use and risk of ovarian cancer: Results from the New England Case-Control study and Nurses' Health Studies

Association of levonorgestrel-releasing intrauterine device with gynecologic and breast cancers: a national cohort study in Sweden

BACKGROUND

The levonorgestrel-releasing intrauterine device (LNG-IUD) is widely used for the treatment of menorrhagia, dysmenorrhea, and for contraception. However, the association between the use of LNG-IUD and the risk of site-specific gynecologic and breast cancers remains inconclusive.

OBJECTIVE

We aim to address this knowledge gap by investigating whether the use of LNG-IUD is associated with a significant risk of site-specific gynecologic and breast cancers. This will be achieved by accessing the nationwide Swedish Registers, with consideration given to the influence and potential interaction of family history of cancer.

STUDY DESIGN

A total of 514,719 women aged 18 to 50 years who have used LNG-IUD between July 2005 and December 2018 were identified from the Swedish Prescribed Drug Register and randomly matched with 1,544,157 comparisons who did not use LNG-IUD at a ratio of 1:3. The propensity score was calculated and matched among women who used LNG-IUD and the matched comparisons. The follow-up period started from the date of the first prescription of LNG-IUD for users as well as for their matched comparisons and ended at the date of diagnosis of gynecologic and breast cancers, date of death from any cause, and the end of the study period, whichever came first. The Cox proportional hazard model with a competing risk analysis was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). Additive interaction was calculated as the relative excess risk for interaction, while multiplicative interaction was calculated by including a product term in the regression model.

RESULTS

The use of LNG-IUD was associated with a 13% higher risk of breast cancer (adjusted HR, 1.13; 95% CI, 1.10-1.17), a 33% lower risk of endometrial cancer (adjusted HR, 0.67; 95% CI, 0.56-0.80), a 14% lower risk of ovarian cancer (adjusted HR, 0.86; 95% CI, 0.75-0.99), and a 9% reduced risk of cervical cancer (adjusted HR, 0.91; 95% CI, 0.84-0.99) compared to women who did not use LNG-IUD. A significant additive interaction between LNG-IUD use and family history of cancer was observed in breast cancer, indicating a relative 19% excess risk for interaction (P<.002), and 1.63 additional cases per 10,000 person-years.

CONCLUSION

The risk of gynecologic and breast cancers exhibits a site-specific effect among LNG-IUD users. It is important to note that the observed effect is small for breast cancer and the results are limited by the observational study design. Clinical recommendations regarding the use of LNG-IUD should carefully weigh its potential benefits and risks. Close monitoring is advisable for the potential development of breast cancer, particularly among women with a family history of breast cancer.

Reevaluating the Role of Progesterone in Ovarian Cancer: Is Progesterone Always Protective?

Ovarian cancer (OC) represents a collection of rare but lethal gynecologic cancers where the difficulty of early detection due to an often-subtle range of abdominal symptoms contributes to high fatality rates. With the exception of BRCA1/2 mutation carriers, OC most often manifests as a post-menopausal disease, a time in which the ovaries regress and circulating reproductive hormones diminish. Progesterone is thought to be a "protective" hormone that counters the proliferative actions of estrogen, as can be observed in the uterus or breast. Like other steroid hormone receptor family members, the transcriptional activity of the nuclear progesterone receptor (nPR) may be ligand dependent or independent and is fully integrated with other ubiquitous cell signaling pathways often altered in cancers. Emerging evidence in OC models challenges the singular protective role of progesterone/nPR. Herein, we integrate the historical perspective of progesterone on OC development and progression with exciting new research findings and critical interpretations to help paint a broader picture of the role of progesterone and nPR signaling in OC. We hope to alleviate some of the controversy around the role of progesterone and give insight into the importance of nPR actions in disease progression. A new perspective on the role of progesterone and nPR signaling integration will raise awareness to the complexity of nPRs and nPR-driven gene regulation in OC, help to reveal novel biomarkers, and lend critical knowledge for the development of better therapeutic strategies.

Incessant ovulation: a review of its importance in predicting cancer risk

Estrous cycles are recurring changes in therian mammals induced by estrogen, progesterone, and other hormones culminating in endometrial proliferation, ovulation, and implantation if fertilization occurred. In women, the estrous cycle is the menstrual cycle; but, unlike most mammals, the end of an infertile cycle is marked by endometrial sloughing and the start of another without an anestrous phase. Women stop cycling at menopause, while in most mammals, cycles continue until death. Epidemiologic studies identified menarche, menopause, births, lactation, and oral contraceptive (OC) use as key risk factors for ovarian, breast, and endometrial cancers. A composite variable was created to estimate the number of cycles not interrupted by events that stop ovulation. Captured by the phrase "incessant ovulation", repetitive cycles were first postulated to affect ovarian cancer risk and later extended to breast and endometrial cancers. These associations could be explained by cumulative effects of repetitive tissue changes within reproductive organs, immune consequences of repetitive ovulation through the glycoprotein mucin 1, and residual effects of past ovulations that enhance ovarian production of testosterone. The latter two pathways could affect the risk for cancers in other organs not considered "reproductive".

Association between intrauterine device use and endometrial, cervical, and ovarian cancer: an expert review

The intrauterine device is one of the most effective forms of contraception. Use of the intrauterine device has increased in the United States over the last 2 decades. Two formulations are commercially available in the United States: the levonorgestrel-releasing intrauterine device and the copper intrauterine device. The levonorgestrel intrauterine device releases progestin, causing endometrial suppression and cervical mucus thickening, whereas the primary mechanism of action of the copper intrauterine device is to create a local inflammatory response to prevent fertilization. Whereas the protective effects of combined hormonal contraception against ovarian and endometrial cancer, and of tubal sterilization against ovarian cancer are generally accepted, less is known about the effects of modern intrauterine devices on the development of gynecologic malignancies. The best evidence for a protective effect of intrauterine device use against cancer incidence pertains to levonorgestrel intrauterine devices and endometrial cancer, although studies suggest that both copper intrauterine devices and levonorgestrel intrauterine devices reduce endometrial cancer risk. This is supported by the proposed dual mechanisms of action including both endometrial suppression and a local inflammatory response. Studies on the relationship between intrauterine device use and ovarian cancer risk show conflicting results, although most data suggest reduced risk of ovarian cancer in intrauterine device users. The proposed biological mechanisms of ovarian cancer reduction (foreign-body inflammatory response, increased pH, antiestrogenic effect, ovulation suppression) vary by type of intrauterine device. Whereas it has been well established that use of copper intrauterine devices confers a lower risk of cervical intraepithelial neoplasms, the effect of levonorgestrel intrauterine device use on cervical cancer remains unclear. Older studies have linked its use to a higher incidence of cervical dysplasia, but more recent literature has found a decrease in cervical cancer with intrauterine device use. Various mechanisms of protection are postulated, including device-related inflammatory response in the endocervical canal and prostaglandin-mediated immunosurveillance. Overall, the available evidence suggests that both levonorgestrel intrauterine devices and copper intrauterine devices reduce gynecologic cancer risk. Whereas there is support for the reduction of endometrial cancer risk with hormonal and copper intrauterine device use, and reduction of cervical cancer risk with copper intrauterine device use, evidence in support of risk reduction with levonorgestrel intrauterine device use for cervical and ovarian cancers is less consistent.

Beyond the pill: contraception and the prevention of hereditary ovarian cancer

BRCA1 and BRCA2 mutation carriers face an elevated lifetime risk of developing ovarian cancer. Oral contraceptives have been shown to significantly decrease the risk of ovarian cancer by approximately 50% in this high-risk population. Changes in contraceptive formulations and patterns of use over time have introduced lower hormonal dosages, different steroid types and non-oral routes of administration. Specifically, there has been a considerable shift in patterns of contraceptive use and the increase in the uptake of non-oral, long-acting, reversible contraception (e.g., intrauterine devices, implants, injections) has corresponded to a decline in oral contraceptive pill use. Whether or not these other methods confer a protective effect against ovarian cancer in the general population is not clear. To our knowledge, there have been no such studies conducted among BRCA mutation carriers. Furthermore, the impact of these changes on the risk of developing ovarian cancer is not known. In this article, we will review the existing epidemiologic evidence regarding the role of contraceptives and the risk of ovarian cancer with a focus on women with a BRCA1 or BRCA2 mutation. We will discuss recent findings and gaps in the knowledge while extrapolating from studies conducted among women from the noncarrier population.

How NPs can eliminate practice barriers to intrauterine device use

ABSTRACT

Barriers to intrauterine device use include cost, absence of qualified providers, the lack of simplified insertion protocols, cultural hesitation, and misconceptions of appropriateness of use. This article outlines how NPs can eliminate practice barriers to intrauterine device use and prevent unintended pregnancy.