Skip Navigation LinksHome > August 2014 - Volume 124 - Issue 2, PART 1 > Cancer Risk in Women Using the Levonorgestrel-Releasing Intr...
Obstetrics & Gynecology:
doi: 10.1097/AOG.0000000000000356
Contents: Original Research

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

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

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Abstract

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=93,843) 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 in 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.

LEVEL OF EVIDENCE: II

© 2014 by The American College of Obstetricians and Gynecologists.

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