Hormonal contraception and risk of breast cancer and breast cancer in situ among Swedish women 15-34 years of age: A nationwide register-based study.

Autor:	Niemeyer Hultstrand J; Department of Women's and Children's Health, Uppsala university, SE-75185 Uppsala, Sweden., Gemzell-Danielsson K; Department of Women's and Children's Health, Karolinska institutet, SE-17177 Stockholm, Sweden., Kallner HK; Department of Women's and Children's Health, Karolinska institutet, SE-17177 Stockholm, Sweden., Lindman H; Department of Immunology, Genetics and Pathology, Uppsala University, Rudbecklaboratoriet, SE-75185 Uppsala, Sweden., Wikman P; Department of Women's and Children's Health, Uppsala university, SE-75185 Uppsala, Sweden., Sundström-Poromaa I; Department of Women's and Children's Health, Uppsala university, SE-75185 Uppsala, Sweden.
Jazyk:	angličtina
Zdroj:	The Lancet regional health. Europe [Lancet Reg Health Eur] 2022 Jul 29; Vol. 21, pp. 100470. Date of Electronic Publication: 2022 Jul 29 (Print Publication: 2022).
DOI:	10.1016/j.lanepe.2022.100470
Abstrakt:	Background: Evidence on a possible association between newer hormonal contraceptives (HC) and risk of breast cancer remains inconclusive, especially as concerns progestogen-only methods. Methods: In this nationwide prospective cohort study, all Swedish women aged 15-34 at study start on January 1 st 2005, or who turned 15 years during the study period, were followed until December 31 st 2017. Using information from seven National Registers, we assessed the risk ratio of developing breast cancer and breast cancer in situ in relation to different HC using Poisson regression. We adjusted the analyses for several known confounders of breast cancer. Findings: This cohort included 1.5 million women providing more than 14 million person-years. During the study period, 3842 women were diagnosed with breast cancer. Compared with never users of any HC, we found no increased risk of developing breast cancer among current users of any combined HC, IRR 1.03 (0.91-1.16), whereas current users of progestogen-only methods had an increased risk of developing breast cancer, IRR 1.32 (1.20-1.45). Across all types of HC, the risk of developing breast cancer appeared to be highest the first five years of use (combined HC IRR 1.39 (1.14-1.69); progestogen-only methods IRR 1.74 (1.44-2.10). The risk disappeared ten years after the women stopped using HC. The absolute risk of breast cancer per 100,000 women-years was 22.4 for never users, 10.9 for current users of combined HC, and 29.8 for current users of progestogen-only methods. Interpretation: Current use of progestogen-only methods is associated with a small increased risk of developing breast cancer, whereas we could only detect an increased risk among users of combined HC during the first five years of use. This may partly be explained by a selective prescription of progestogen-only methods to women with risk factors for breast cancer, like smoking or obesity. As the absolute risk of breast cancer was small, the many health benefits associated with HC must also be taken into account in contraceptive counselling. Funding: This study was funded by the Swedish Cancer Society and by the Uppsala County Council, the Faculty of Medicine at Uppsala University. Competing Interests: Jenny Niemeyer Hultstrand has received funding from the Family Planning Fund, Uppsala University, and travel grants from the Swedish Society of Medicine. Kristina Gemzell-Danielsson has acted as consultant for Bayer, Gedeon Richter, Exeltis, Natural Cycles, Daisy, Medincell, Cirqle, ObsEva, Mithra, Vifor. She has received lecture fees from Bayer, Gedeon Richter, Exeltis, Nordic Pharma, Natural Cycles, Mithra, and Organon. Helena Kopp Kallner has received lecture fees from: Actavis, Bayer, Gedeon Richter Exeltis, Nordic Pharma, Natural Cycles, Mithra, Teva, Merck, Ferring, Consilient Health, and acted as consultant for Bayer, Evolan, Gedeon Richter, Exeltis, Merck, Teva, TV4, Natural Cycles, Pharmiva, Dynamic Code, Ellen, Estercare, Leia and Essity. Henrik Lindman has received lecture fees from Lilly, AstraZeneca, Novartis, and Daiichi Sankyo. Per Wikman reports no conflicts of interest. Inger Sundström Poromaa has served occasionally on advisory boards or acted as invited speaker at scientific meetings for Bayer Health Care, Gedeon Richter, Peptonics, Shire/Takeda, and Sandoz. ISP is supported by grants from the Swedish Research Council 2020-01801 and the Swedish Cancer Society. (© 2022 The Authors.)
Databáze:	MEDLINE
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