Medical Program: Is There a Link Between IUD Use & Breast Cancer Risk?

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Is There a Link Between IUD Use & Breast Cancer Risk?

Is There a Link Between IUD Use & Breast Cancer Risk?
    Find out more about the link between premenopausal use of hormonal intrauterine treatments for menorrhagia and risk of breast cancer.
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    • Overview

      This episode of Audio Abstracts reviews two studies conducted in Finland that investigated the link between premenopausal use of hormonal intrauterine treatment for menorrhagia and breast cancer incidence rates. 

      The first study, Cancer Risk in Women Using the Levonorgestrel-Releasing Intrauterine System in Finland, examined the incidence rates of several common cancers among intrauterine treatment users. The authors found that the risk of breast cancer increased within this patient population, while all other cancer risk profiles decreased.

      As a follow-up to this study, a second publication titled Levonorgestrel-Releasing Intrauterine System and the Risk of Breast Cancer: A Nationwide Cohort Study, reported that patients using this IUD were at an increased risk of lobular and ductal breast cancers, specifically.

    • Cancer Risk in Women Using the Levonorgestrel-Releasing Intrauterine System in Finland

      Tuuli Soini, MD, Ritva Hurskainen, MD, Seija Grénman, MD, Johanna Mäenpää, MD, Jorma Paavonen, MD, and Eero Pukkala, PhD

      Obstet Gynecol. 2014 Aug;124(2 Pt 1):292-9. doi: 10.1097/AOG.0000000000000356.


      OBJECTIVE: To examine the association between premenopausal use of the levonorgestrel-releasing intrauterine system and cancer incidence in Finland with a special focus on endometrial adenocarcinoma.

      METHODS: All Finnish women aged 30–49 years using a levonorgestrel-releasing intrauterine system for treatment of menorrhagia in 1994–2007 (n 593,843) were identified from the National Reimbursement Registry and linked to the Finnish Cancer Registry data. The incidence of cancers in levonorgestrel-releasing intrauterine system users was compared with that of the general population. 

      RESULTS: A total of 2,781 cancer cases were detected in levonorgestrel-releasing intrauterine system users during the follow-up of 855,324 women-years. The standardized incidence ratio (observed-to-expected ratio) for endometrial adenocarcinoma was 0.50 (95% confidence interval [CI] 0.35–0.70; 34 observed compared with 68 expected cases) after the first levonorgestrel-releasing intrauterine system purchase and 0.25 (95% CI 0.05–0.73; three observed compared with 12 expected cases) after two purchases. The standardized incidence ratio for ovarian cancer was 0.60 (95% CI 0.45–0.76; 59 observed compared with 99 expected cases), for pancreatic cancer 0.50 (95% CI 0.28–0.81; 15 observed compared with 30 expected cases), and for lung cancer 0.68 (95% CI 0.49–0.91; 43 observed compared with 63 expected cases). The standardized incidence ratio for breast cancer among all levonorgestrel-releasing intrauterine system users was 1.19 (95% CI 1.13–1.25; 1,542 observed compared with 1,292 expected cases).

      CONCLUSION: The levonorgestrel-releasing intrauterine system may have a protective effect against endometrial malignant transformation. Using the levonorgestrel-releasing intrauterine system for treatment of menorrhagia during reproductive years was associated with a lower incidence of endometrial, ovarian, pancreatic, and lung cancers than expected. Levonorgestrel-releasing intrauterine system use was associated with a higher than expected incidence of breast cancer.

    • Levonorgestrel-releasing intrauterine system and the risk of breast cancer: A nationwide cohort study

      Tuuli Soini, Ritva Hurskainen, Seija Grénman, Johanna Mäenpää, Jorma Paavonen, Heikki Joensuu & Eero Pukkala 

      Tuuli Soini, Ritva Hurskainen, Seija Grénman, Johanna Mäenpää, Jorma Paavonen, Heikki Joensuu & Eero Pukkala (2016) Levonorgestrel-releasing intrauterine system and the risk of breast cancer: A nationwide cohort study, Acta Oncologica, 55:2, 188-192, DOI: 10.3109/0284186X.2015.1062538


      Background. Prolonged steroid hormone therapy increases the risk of breast cancer, especially the risk of lobular cancer, but the effect of the levonorgestrel-releasing intrauterine system (LNG-IUS) use is controversial. In this study we aimed to test the hypothesis that risk for lobular breast cancer is elevated among LNG-IUS users. 

      Material and methods. We identified from the National Medical Reimbursement Registry of Finland the women aged 30 – 49 who had used LNG-IUS for the treatment or prevention of menorrhagia in 1994 – 2007, and from the Finnish Cancer Registry breast cancers diagnosed before the age of 55 and by the end of 2012. 

      Results. A total of 2015 women had breast cancer diagnosed in a cohort of 93 843 LNG-IUS users during follow-up consisting of 1 032 767 women-years. The LNG-IUS users had an increased risk for both ductal breast cancer [standardized incidence ratio (SIR) 1.20, 95% confi dence interval (CI) 1.14 – 1.25] and for lobular breast cancer (SIR 1.33, 95% CI 1.20 – 1.46), as compared with the general female population. The highest risk was found in LNG-IUS users who purchased the device at least twice, whose SIR for lobular cancer was 1.73 (95% CI 1.37 – 2.15).

      Conclusions. The results imply that intrauterine administration of levonorgestrel is not only related to an excess risk of lobular breast cancer but also, in contrary to previous assumptions, to an excess risk of ductal breast cancer.

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