Research article

CYP17 gene polymorphism in relation to breast cancer risk: a case-control study

Kristjana Einarsdóttir^1,2 , Tove Rylander-Rudqvist³ , Keith Humphreys¹ , Susanne Ahlberg⁴ , Gudrun Jonasdottir¹ , Elisabete Weiderpass^1,5 , Kee Seng Chia⁶ , Magnus Ingelman-Sundberg⁴ , Ingemar Persson^1,7 , Jianjun Liu² , Per Hall¹ and Sara Wedrén^1,2,6

¹  Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden

²  Population Genetics, Genome Institute of Singapore, Singapore

³  Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden

⁴  Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden

⁵  Cancer Registry of Norway, Montebello, Oslo, Norway

⁶  Centre for Molecular Epidemiology, Department of Community, Occupational and Family Medicine, National University of Singapore, Singapore

⁷  Swedish Medical Products Agency, Uppsala, Sweden

author email corresponding author email

Breast Cancer Research 2005, 7:R890-R896doi:10.1186/bcr1319

Published:	14 September 2005

See related commentary by Little and Simard http://breast-cancer-research.com/content/7/6/238

Abstract

Introduction

The c.1-34T>C 5' promoter region polymorphism in cytochrome P450c17 (CYP17), a key enzyme in the biosynthesis of estrogen, has been associated with breast cancer risk, but most previous studies have been relatively small.

Methods

We genotyped 1,544 incident cases of primary breast cancer and 1,502 population controls, all postmenopausal Swedish women, for the CYP17 c.1-34T>C polymorphism and calculated odds ratios (ORs) and 95% confidence intervals (CIs) from logistic regression models.

Results

No overall association was found between CYP17 c.1-34T>C and breast cancer risk, OR 1.0 (95% CI 0.8–1.3) for the A2/A2 (CC) carriers compared to the A1/A1 (TT) carriers, regardless of histopathology. We detected an interaction between CYP17 c.1-34T>C and age at menarche (P = 0.026) but regarded that as a chance finding as no dose-response pattern was evident. Other breast cancer risk factors, including menopausal hormone use and diabetes mellitus, did not modify the overall results.

Conclusion

It is unlikely that CYP17 c.1-34T>C has a role in breast cancer etiology, overall or in combination with established non-genetic breast cancer risk factors.