Coffee prevents early events in tamoxifen-treated breast cancer patients and modulates hormone receptor status.Simonsson, Maria; Söderlind, Viktoria; Henningson, Maria; Hjertberg, Maria; Rose, Carsten; Ingvar, Christian; Jernström, Helena General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Moderate to high coffee consumption was associated with significantly decreased risk for early events in tamoxifen-treated patients and modified hormone receptor status. If confirmed, new recommendations regarding coffee consumption during tamoxifen-treatment may be warranted.

Whether coffee modulates response to endocrine therapy in breast cancer patients is currently unknown. The CYP1A2 and CYP2C8 enzymes contribute to tamoxifen and caffeine metabolism. The aim was to investigate the impact of coffee consumption on tumor characteristics and disease-free survival in relation to breast cancer treatment and CYP1A2 and CYP2C8 genotypes. Questionnaires regarding lifestyle were completed preoperatively by 592 patients in Southern Sweden. CYP1A2*1F and CYP2C8*3 were genotyped. Clinical data and tumor characteristics were obtained from patients’ charts, population registries, and pathology reports. Coffee consumption was categorized as low (0-1 cups/day), moderate (2-4 cups/day), or high (5+cups/day). The proportion of estrogen receptor negative (ER-) tumors increased with increasing coffee consumption (Ptrend=0.042). Low consumption was associated with higher frequency of discordant receptor status (ER+PgR-) OR 2.61 (1.59-4.29) compared to higher consumption. Median follow-up time was 4.92 years. Tamoxifen-treated patients with low consumption had significantly increased risk for early events compared to patients who consumed two or more cups/day, adjusted HR 2.50 (1.20-5.26). Low coffee consumption was also associated with higher risk for distant metastases in tamoxifen-treated patients with ER+ tumors, adjusted HR 2.43 (1.00-5.88). Low consumption combined with at least one CYP1A2*1F C-allele or CYP2C8*3 was associated with a high risk for early events in tamoxifen-treated patients, adjusted HRs 3.49 (1.54-7.90) and 6.14 (2.46-15.34), respectively. In conclusion, a moderate to high coffee consumption of caffeinated coffee was associated with significantly lower risk for early breast cancer events in tamoxifen-treated patients. This may be due to modification of the hormone receptor status or altered CYP enzyme activity. If confirmed, new recommendations regarding coffee consumption during tamoxifen-treatment may be warranted. Citation Format: Maria Simonsson, Viktoria Söderlind, Maria Henningson, Maria Hietala, Carsten Rose, Christian Ingvar, Helena C. Jernström. Coffee prevents early events in tamoxifen-treated breast cancer patients and modulates hormone receptor status. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 108. doi:10.1158/1538-7445.AM2013-108