Association of partner vasectomy, depot medroxyprogesterone acetate and intrauterine contraceptive devices with ovarian cancer

Common myths and misconceptions surrounding hormonal contraception

Numerous community and professional myths and misconceptions around hormonal contraception exist, many promulgated through social media. As a result of these and other factors, people are moving away from hormonal methods and potentially exposing themselves to increased risk of unintended pregnancy. A number of key myths and misconceptions have been identified in a range of papers and here we summarise the evidence around the basis for these misunderstandings. The themes we explore are the physical side effects, the mental health effects, the impact on sexuality, the concerns about infertility, the concept of "unnaturalness", concerns about menstruation, concerns about safety and destigmatisation of side effects. For many of these themes, there is some evidence justifying the concern, but overall for most people, we argue that the benefits of hormonal contraception outweigh the disadvantages.

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.

Method of contraception and risk of ovarian cancer data

The data presented here were obtained for a New Zealand nationwide population-based case-control analysis undertaken to assess the association between ovarian cancer and depot medroxyprogesterone acetate (DMPA), intrauterine contraceptive devices (IUDs), and vasectomy of a woman's sexual partner (Chesang et al., 2021). The research involved women aged 35 to 69 years. Controls were randomly selected from the New Zealand electoral roll. Cases were women with a diagnosis of incident ovarian cancer recruited from the New Zealand Cancer Registry and had to be listed on the electoral roll. Data collection was conducted between 1st May 2013 and 31st October, 2015. A structured postal questionnaire was used to gather information. Data were analysed using IBM Statistical Package for the Social Sciences (IBM SPSS statistics 22). Odds ratios adjusted for age were calculated using the method of Mantel and Haensze (Rosner et al., 2007). For multivariable analyses, binary logistic regression was used. Description of study participants and age-adjusted and multivariable analyses of the association between ever-use and specifics of use of DMPA, IUDs, and vasectomy were presented in a journal article (Chesang et al., 2021). Here, we present data from analyses of the risk of ovarian cancer by histological type associated with the use of DMPA, IUDs and ever having had a vasectomised partner. In addition, analyses assessing the association between ovarian cancer and these contraceptives restricted to ever-users and never-users of hormonal contraceptives (defined as oral contraceptives or DMPA) are presented. Data from analyses of the association between history of tubal ligation and the risk of ovarian cancer are also presented. These data, including the findings of a related study (Chesang et al., 2021) and the raw data, can be included in a collaborative analysis of existing studies undertaken to assess the association between IUDs, long-acting progestogen-based contraceptives, and partner vasectomy and the risk of ovarian cancer.