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Cancer Epidemiology Biomarkers & Prevention 16, 1318-1320, June 1, 2007. doi: 10.1158/1055-9965.EPI-07-0084
© 2007 American Association for Cancer Research
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Null Results in Brief

Lack of Effect Modification between Estrogen Metabolism Genotypes and Combined Hormone Replacement Therapy in Postmenopausal Breast Cancer Risk

Timothy R. Rebbeck1,2, Andrea B. Troxel1,2, Ekaterina G. Shatalova5, Rebecca Blanchard5, Sandra Norman1,2, Greta Bunin1,2,4, Angela DeMichele1,2,3, Rita Schinnar1, Jesse A. Berlin1,2 and Brian L. Strom1,2,3

1 Center for Clinical Epidemiology and Biostatistics and Department of Biostatistics and Epidemiology; 2 Abramson Cancer Center, 3 Department of Medicine, 4 Division of Oncology, Children's Hospital of Philadelphia, and 5 Fox Chase Cancer Center, Philadelphia, Pennsylvania

Requests for reprints: Timothy Rebbeck, Department of Biostatistics and Epidemiology, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, 904 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104-6021. Phone: 215-898-1793; Fax: 215-898-2265. E-mail: trebbeck{at}cceb.med.upenn.edu


   Introduction
Top
 Introduction
Materials and Methods
 Results and Discussion
 References
 
Postmenopausal use of combined hormone replacement therapy (CHRT) containing both estrogens and progestins has been associated with increased breast cancer risk (1, 2). There is also evidence that genetic variants in candidate estrogen metabolism genes influence the disposition of exogenous estrogen. The genes involved in the disposition of estrogen are well known, and include catechol-O-methyltransferase (COMT), the sulfotransferases SULT1A1 and SULT1E1, and members of the cytochrome P50 family including CYP1B1, CYP1A2, and CYP1A1. Functionally relevant genetic variants exist in each of these genes. However, it remains unclear whether these genes affect breast cancer risk (3-10), and there is even less information about whether these genes interact with relevant exposures to influence breast cancer etiology. Therefore, we evaluated whether there was evidence for modification of the effect of CHRT use by genes involved in the downstream metabolism of estrogens including COMT, CYP1A1, CYP1A2, CYP1B1, SULT1A1, and SULT1E1.


   Materials and Methods
Top
 Introduction
 Materials and Methods
Results and Discussion
 References
 
The Women's Insights and Shared Experiences (WISE) study is a population-based case-control study that consisted of an efficient sampling design using shared controls to compare both breast cancer cases and endometrial cancer cases (11, 12). Incident breast cancer cases were identified through hospitals and the Pennsylvania State Cancer Registry, and frequency-matched controls were identified from the community using random-digit dialing. The source populations for this study were the three counties of Philadelphia (PA), Delaware (PA), and Camden (NJ). Potentially eligible cases were Caucasian women residing in these counties at the time of diagnosis who were ages 50 to 79 years old and were newly diagnosed with breast cancer between July 1, 1999 and June 30, 2002. Controls were selected from the same geographic regions as the cases, and were frequency-matched to the cases on age (in 5-year age groups) and calendar date of interview (within 3 months). The present analysis involved 677 breast cancer cases and 905 age-matched controls who met the abovementioned criteria. Genomic DNA was obtained from buccal swabs as previously described. Genetic variants in COMT, CYP1A1, CYP1A2, CYP1B1, SULT1A1, and SULT1E1 were assayed as previously described (13). Additional details of our study design, which included ascertainment of both breast and endometrial cancer cases and matched controls, have been previously reported (11-14).

Odds ratio (OR) estimates and 95% confidence intervals were calculated to evaluate the relationship between hormone metabolism genes and hormone use with breast cancer risk. Using multiple conditional logistic regression, we adjusted for (a) education (<high school, high school graduate, more than high school but not a college graduate, college graduate or higher); (b) body mass index during the participant's 40's; (c) number of full-term pregnancies (0, 1, 2, 3+); (d) years of menses; (e) menopause type (known natural, assumed natural at reference age of 50 if menopausal status is unknown, and induced); (f) never/former/current smoker x years of smoking; and (g) oral contraceptive use (never, <3 years, 3 years or more). Adjustment for other covariates had no substantial effect on the ORs of interest. Two degrees of freedom {chi}2 tests for interaction of genotype by CHRT use were computed.


   Results and Discussion
Top
 Introduction
 Materials and Methods
 Results and Discussion
References
 
As shown in Table 1 , we identified no statistically significant modification of the effect of CHRT use and any genotype (Table 1). Statistically significant stratum-specific ORs were identified among never users of CHRT for carriers of CYP1A1*2C or SULT1A1*3 alleles. However, our a priori hypotheses specified that only statistically significant effect modification existed according to genotype with CHRT use. Thus, we did not consider stratum-specific OR effects as meaningful if no statistically significant interaction was observed. Similarly, no significant effect modification was observed for subgroups based on histology (ductal, lobular) or estrogen receptor or progesterone receptor status (results not shown). Therefore, the present results do not support the hypothesis that estrogen metabolism genotypes modify the effect of CHRT in breast cancer etiology among postmenopausal Caucasian women.


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  		Table 1. Genes and alleles under study, with adjusted ORs (95% confidence intervals) for effect modification of genotypes and CHRT use on breast cancer risk in postmenopausal Caucasian women

 
We attempted to limit the potential for inferential errors by restricting our analyses to Caucasians, thus eliminating the majority of the variability that could lead to confounding by ethnicity, and can lead to either false-positive or false-negative associations (15). In all studies involving effect modification, power and sample size considerations are critical when evaluating the potential for type II error. Our study was originally designed with sufficient statistical power to detect first-order interactions of the type evaluated here between genotypes and CHRT use. The study was originally designed to ascertain 564 postmenopausal Caucasian cases and 719 matched postmenopausal Caucasian controls, which would provide 80% power to detect a first-order interaction between genotype classes (e.g., carriage of any variant allele in homozygous or heterozygous form) with a frequency of 5% or greater and an exposure (e.g., CHRT) with an exposure frequency of 60% or greater to detect an interaction OR of 2.2, assuming {alpha} = 0.05. The final sample size used here was 677 postmenopausal Caucasian cases and 905 matched postmenopausal Caucasian controls. In addition, the frequency of genotypes was generally higher than originally planned. Therefore, the study had greater power than originally designed, and provides adequate power to detect clinically relevant interactions had they been observed here.

We report that the elevated breast cancer risk associated with CHRT use is unlikely to be influenced by functionally relevant variants in candidate estrogen metabolism genes. These results suggest that breast cancer risk in women who use CHRT does not depend on genetic factors involved in estrogen metabolism. Additional research is required to evaluate whether the metabolism of other compounds, including progestins, might explain the elevated breast cancer risk associated with CHRT use.


   Acknowledgments
 
The authors thank Drs. J.A. Grisso, Michelle Berlin, and Mona Baumgarten for their central roles in the development and execution of this research, the database manager Dr. Anita L. Weber, the Project Manager for the Hospital Network Core, Elene Turzo, and the Project Manager for the Field Core, Desiree Burgh, for their incredible efforts in coordinating the logistical aspects of obtaining Institutional Review Board approvals in participating hospitals and for ascertaining and recruiting the large number of participants in this study. Our thanks to Karen Venuto who managed the tracking database and the vast correspondence involved in this study, to Shawn Fernandes for performing extensive quality control checks and helping with the development of the questionnaire database, to Stephen Gallagher for data management, and to Amy Walker and Saarene Panossian for laboratory analyses. We are grateful for the cooperation of the hospitals in the Greater Delaware Valley and the support of the physicians who sponsored our study in these institutions, as without this help we could not have performed this study.


   Footnotes
 
Grant support: Public Health Service (P01-CA77596).

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Note: Current address for R. Blanchard: Merck, Blue Bell, Pennsylvania. Current address for J.A. Berlin: Johnson and Johnson, Pharmaceutical Research and Development, Titusville, New Jersey.

Received 1/29/07; revised 2/13/07; accepted 3/26/07.


   References
Top
 Introduction
 Materials and Methods
 Results and Discussion
 References
 

  1. Anonymous. Breast cancer and hormone replacement therapy: collaborative reanalysis of data from 51 epidemiological studies of 52,705 women with breast cancer and 108,411 women without breast cancer. Collaborative Group on Hormonal Factors in Breast Cancer [see comment][erratum appears in Lancet 1997 Nov 15;350(9089):1484]. Lancet 1997;350:1047–59.[CrossRef][Medline]
  2. Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial. JAMA 2002;288:321–33.[Abstract/Free Full Text]
  3. Haiman C, Hankinson SE, Colditz GA, Hunter DJ, De Vivo I. A polymorphism in CYP17 and breast cancer risk. Cancer Res 2001;61:3955–60.[Abstract/Free Full Text]
  4. Paynter RA, Hankinson SE, Colditz GA, Kraft P, Hunter DJ. De Vivo I, CYP19 (aromatase) haplotypes and endometrial cancer risk. Int J Cancer 2005;116:267–74.[CrossRef][Medline]
  5. McGrath M, Hankinson SE, Arbeitman L, Colditz GA, Hunter DJ. De Vivo I, Cytochrome P450 1B1 and catechol-O-methyltransferase polymorphisms and endometrial cancer susceptibility. Carcinogenesis 2004;25:559–65.[Abstract/Free Full Text]
  6. Rylander-Rudqvist T, Wedren S, Granath F, et al. Cytochrome P450 1B1 gene polymorphisms and postmenopausal breast cancer risk. Carcinogenesis 2003;24:1533–9.[Abstract/Free Full Text]
  7. Doherty JA, Weiss NS, Freeman RJ, et al. Genetic factors in catechol estrogen metabolism in relation to the risk of endometrial cancer. Cancer Epidemiol Biomarkers Prev 2005;14:357–66.[Abstract/Free Full Text]
  8. Sasaki MTY, Kaneuchi M, Sakuragi N, Dahiya R. CYP1B1 gene polymorphisms have higher risk for breast cancer, and positive correlations with estrogen receptor {alpha} and estrogen receptor ß expressions. Cancer Res 2003;63:3913–8.[Abstract/Free Full Text]
  9. De Vivo I, Hankinson SE, Colditz GA, Hunter DJ. A functional polymorphism in the progesterone receptor gene is associated with an increase in breast cancer risk. Cancer Res 2003;63:5236–8.[Abstract/Free Full Text]
  10. Le Marchand L, Donlon T, Kolonel LN, Henderson BE, Wilkens LR. Estrogen metabolism-related genes and breast cancer risk: the multiethnic cohort study. Cancer Epidemiol Biomarkers Prev 2005;14:1998–2003.[Abstract/Free Full Text]
  11. Bunin GR, Baumgarten M, Norman SA, Strom BL, Berlin JA. Practical aspects of sharing controls between case-control studies. Pharmacoepidemiol Drug Saf 2005;14:523–30.[CrossRef][Medline]
  12. Rebbeck T, Troxel A, Walker A, et al. Pairwise combinations of estrogen metabolism genotypes in post menopausal breast cancer etiology. Cancer Epidemiol Biomarkers Prev 2007;16:444–50.[Abstract/Free Full Text]
  13. Rebbeck TR, Troxel AB, Wang Y, et al. Estrogen sulfation genes, hormone replacement therapy, and endometrial cancer risk. J Natl Cancer Inst 2006;98:1311–20.[Abstract/Free Full Text]
  14. Strom BL, Schinnar R, Weber AL, et al. Case-control study of postmenopausal hormone replacement therapy and endometrial cancer. Am J Epidemiol 2006;164:775–86.[Abstract/Free Full Text]
  15. Wang Y, Localio R, Rebbeck TR. Evaluating bias due to population stratification in case-control association studies of admixed populations. Genet Epidemiol 2004;27:14–20.[CrossRef][Medline]



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