Women Using Intrauterine Devices Increase Risk of Breast Cancer
Mar 24, 2025
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Professor Yuk Jin-sung of obstetrics and gynecology at Sanggye Paik Hospital of Inje University and Professor Noh Ji-hyun's research team compared LNG-IUS use and the risk of breast cancer in 61,1010 women aged 30 to 49 years diagnosed with endometriosis, uterine myoma, or abnormal uterine bleeding from 2014 to 2017.
Studies have shown that women with LNG-IUS have 223 breast cancer cases per 100,000, compared with non-users (154 cases per 100,000), with a 38% increased risk of breast cancer (risk ratio HR 1.38, 95% confidence interval 1.192-1.585). This is in part consistent with the results of Danish researcher ø et al. (2017, New England Journal of Medicine) reporting a 21% increase in breast cancer risk (relative risk 1.21 and 95% confidence interval 1.11-1.33) due to LNG-IUS use.
In particular, in this study, the risk of breast cancer increased sharply to 5.4 times (HR 5.40, 95% confidence interval 4.037-7.216) when using LNG-IUS for less than 3 years, but the risk tended to decrease to 1.77 times (HR 1.77, 95% confidence interval 1.26-2.479) when used for more than 5 years.
Professor Yuk Jin-Sung, the first author, emphasized that "The possibility of increased breast cancer risk should be considered when using LNG-IUS, but it is important that the risk changes depending on the duration of use." He explained "It is also possible that the rapid increase in breast cancer risk during the initial three years is due to the relatively high level of levonorgestrel in the blood causing breast pain, and thus the increased frequency of breast examinations." "However, the fact that the risk of breast cancer tends to increase continuously even when used for more than five years suggests a biological association beyond simple screening effects."
Professor Noh Ji-hyun, the corresponding author, said, "This study is significant in that it confirmed the association between LNG-IUS and breast cancer incidence based on Korean women's data. Compared to studies such as M ø, we reaffirmed the possibility of LNG-IUS increasing the risk of breast cancer." He stressed that "However, not all women are at the same risk, so considering LNG-IUS use, the advantages of contraceptive effect, improvement of excessive menarche, and the possibility of increased breast cancer risk should be comprehensively reviewed."
The study was published in the latest issue of Obstetrics & Gynology (Green Journal), an official journal of the American College of Obstetrics and Gynecology, and is expected to provide an important basis for long-term safety assessment of LNG-IUS use and establishing individual customized counseling strategies.
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This article was translated by Naver AI translator.
