Annals of Oncology Advance Access published online on September 4, 2007
Annals of Oncology, doi:10.1093/annonc/mdm404
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© 2007 European Society for Medical Oncology
Menopause hormone replacement therapy and cancer risk: an Italian record linkage investigation
1 Department of Statistics; Unit of Epidemiology and Biostatistics, University of Milan-Bicocca
2 Mario Negri Institute of Pharmacological Research
3 Institute of Medical Statistics and Biometry, University of Milan
4 Research Center on Chronic Degenerative Diseases, University of Milan-Bicocca
5 Cancer Registry Division, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan
6 Department of Morphological, Eidological and Clinical Sciences, Research Center for Reproductive Medicine, University of Pavia
7 Endocrinology and Internal Medicine Unit, Section of Gynaecological Endocrinology, Istituto di ricovero e cura carattere scientifico (IRCCS) Maugeri Foundation, University of Pavia, Pavia
8 Operative Unit of Territorial Health Services, Region Lombardia, Milan, Italy
* Correspondence to: Prof. G. Corrao, Dipartimento di Statistica, Università degli Studi di Milano-Bicocca, Via Bicocca degli Arcimboldi 8, Edificio U7, 20126 Milano, Italy. Tel: +39-02-64485854; Fax: +39-02-64485899; E-mail: giovanni.corrao{at}unimib.it
Background: The effects of persistence with hormone replacement therapy (HRT) on the risk of hospitalization for cancer and of the route of HRT administration on the risk of breast and colorectal cancer were explored in a large cohort study.
Patients and methods: The 73 505 women residing in Lombardia (Italy), aged 45–75 years, who received at least one HRT prescription during 1998–2000 were followed until 2005. Among these, 3687 experienced cancer hospitalization. Proportional hazards model was fitted to estimate the association between cumulative HRT persistence and cancer risk.
Results: Compared with women who took HRT for <6 months, those exposed for >2 years showed hazard ratios (HR) of 0.78 (95% confidence interval 0.68–0.92) for colorectal cancer and 1.34 (1.13–1.58) for breast cancer. HR for breast cancer associated with long-term use of transdermal and oral HRT were, respectively, 1.27 (1.07–1.51) and 2.14 (1.43–3.21).
Conclusions: Evidence that long-term use of HRT is associated with increased risk of breast cancer and decreased risk of colorectal cancer is supplied from this study from a southern European population. Our findings indicate that transdermal therapy might have lower effect than oral therapy in increasing breast cancer risk.
cohort study, database, hormone replacement therapy, neoplasms, oral administration, transdermal administration
Received for publication April 3, 2007. Revision received July 12, 2007. Accepted for publication July 16, 2007.