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Anderson W.F.,U.S. National Cancer Institute | Rosenberg P.S.,U.S. National Cancer Institute | Petito L.,U.S. National Cancer Institute | Katki H.A.,U.S. National Cancer Institute | And 5 more authors.
International Journal of Cancer | Year: 2013

Long-term breast cancer trends in incidence in the United States (US) show rising estrogen receptor (ER)-positive rates and falling ER-negative rates. We hypothesized that these divergent trends reflect etiologic heterogeneity and that comparable trends should be observed in other countries with similar risk factor profiles. Therefore, we analyzed invasive female breast cancers in Denmark, a country with similar risk factors as the US. We summarized the overall trend in age-standardized rates with the estimated annual percentage change (EAPC) statistic (1993-2010) and used age-period-cohort models to estimate age-specific EAPCs, cohort rate ratios and projections for future time periods (2011-2018). In Denmark, the overall rate of ER-positive cancers rose between 1993 and 2010 by 3.0% per year (95% CI: 2.8-3.3% per year), whereas the overall rate of ER-negative cancers fell by 2.1% per year (95% CI: -2.5 to -1.6% per year). The ER-positive rate increased fastest among postmenopausal women and the ER-negative rate decreased fastest among premenopausal women, reflecting that cohorts born after 1944 were at relatively higher risk of ER-positive tumors and lower risk of ER-negative tumors. If current trends continue, ER-positive cancers will increase at least 13% by 2018 in Denmark, ER-negative cancers will fall 15% by 2018, and breast cancer overall will increase at least 7% by 2018. Divergent ER-specific trends are consistent with distinct etiologic pathways. If trends in known risk factors are responsible, the Danish and US experience may foreshadow a common pattern worldwide. What's new? Estrogen receptor- (ER-)negative breast cancer incidence rates are declining nationwide in Denmark and the United States, whereas rates for ER-positive breast cancers are rising. This report suggests that the divergent trends in ER breast cancers in both countries can be explained by parallel trends in environmental and lifestyle factors that are known to either increase or decrease risk for ER-positive or ER-negative malignancies. The patterns observed in Denmark and the United States may foreshadow a common pattern for many countries worldwide. Copyright © 2013 UICC.

Lash T.L.,Aarhus University Hospital | Lash T.L.,Boston University | Cronin-Fenton D.,Aarhus University Hospital | Ahern T.P.,Boston University | And 12 more authors.
Acta Oncologica | Year: 2010

Background. Up to one-quarter of breast cancer patients suffer clinically significant depression in the year after diagnosis, which may respond to intervention. About half may be prescribed a psychotropic medication, such as a selective serotonin reuptake inhibitor (SSRI), while completing breast cancer therapy. Cytochrome P-450 2D6 (CYP2D6) metabolizes SSRIs and also metabolizes tamoxifen to more active forms. Therefore, concurrent use of SSRIs may reduce tamoxifen's effectiveness at preventing breast cancer recurrence. The SSRI citalopram has limited potency to inhibit CYP2D6 activity, so has been recommended for breast cancer patients taking tamoxifen. This study provides epidemiologic evidence to support this recommendation. Material and methods. We conducted a case-control study of breast cancer recurrence nested in the population of female residents of Denmark who were diagnosed with non-metastatic estrogen-receptor positive breast cancers between 1994 and 2001 and who took tamoxifen for at least one year. We ascertained complete prescription histories by linking cases' and controls' civil registration numbers to the Danish national prescription registry. We estimated the association between SSRI use while taking tamoxifen and risk of recurrent breast cancer. Results. About the same proportion of recurrent cases (37 of 366) and matched controls (35 of 366) received at least one prescription for citalopram or its s-stereoisomer while taking tamoxifen (adjusted odds ratio = 1.1, 95% confidence interval = 0.7, 1.7). Breast cancer patients taking other SSRIs were also at no increased risk of recurrence (adjusted odds ratio = 0.9, 95% confidence interval = 0.5, 1.8). Discussion. Breast cancer patients with indications for an SSRI may be prescribed citalopram and possibly other SSRI without adversely affecting the outcome of adjuvant therapy with tamoxifen. © 2010 Informa UK Ltd.

Lash T.L.,Aarhus University Hospital | Lash T.L.,Boston University | Cronin-Fenton D.,Aarhus University Hospital | Ahern T.P.,Boston University | And 12 more authors.
Journal of the National Cancer Institute | Year: 2011

Background Cytochrome P450 2D6 (CYP2D6) inhibition reduces the concentration of 4-hydroxylated tamoxifen metabolites, but the clinical relevance remains uncertain. Methods We conducted a large case-control study nested in the population of 11251 women aged 35-69 years at diagnosis of stage I-III breast cancer between 1985 and 2001 on Denmark's Jutland Peninsula and registered with the Danish Breast Cancer Cooperative Group. We identified 541 recurrent or contralateral breast cancers among women with estrogen receptor-positive (ER+) disease treated with tamoxifen for at least 1 year and 300 cancers in women with ER-negative (ER-) disease never treated with tamoxifen. We matched one control subject per case patient on ER status, menopausal status, stage, calendar time, and county, genotyped the CYP2D6*4 allele to assess genetic inhibition, and ascertained prescription history to assess drug-drug inhibition. We estimated the odds ratio (OR), associating CYP2D6 inhibition with breast cancer recurrence and adjusted for potential confounding with logistic regression. To address bias from incomplete information on CYP2D6 function, we used Monte Carlo simulation to complete a record-level probabilistic bias analysis. All statistical tests were two-sided. Results The frequency of the CYP2D6*4 minor allele was 24% in case patients with ER+ tumors, 23% in case patients with ER- tumors, and 22% each in control subjects with ER+ and ER- tumors. In women with ER+ tumors, the associations of one functional allele with recurrence (OR = 0.99; 95% confidence interval = 0.76 to 1.3) and no functional allele with recurrence (OR = 1.4; 95% confidence interval = 0.84 to 2.3) were near null, as were those for women with ER- tumors. The near-null associations persisted when evaluated by intake of medications, by combining genotype with medication history, in the probabilistic bias analysis, or by restricting the analysis to women with ER expression confirmed by re-assay. Conclusion The association between CYP2D6 inhibition and recurrence in tamoxifen-treated patients is likely null or small. © 2011 The Author. Published by Oxford University Press. All rights reserved.

Eckhoff L.,University of Southern Denmark | Nielsen M.,University of Southern Denmark | Moeller S.,Danish Breast Cancer Cooperative Group DBCG | Knoop A.,University of Southern Denmark
Acta Oncologica | Year: 2011

Background. In 2007 docetaxel was introduced as part of the adjuvant setting offered to high risk breast cancer patients in Denmark. Meta-analyses had shown that taxane-containing chemotherapy reduced the relative risk of relapse and death by 2030%, apparently with moderate side effects. The treatment was given as three cycles of cyclophosphamide (600 mg/m 2) and epirubicin (90 mg/m 2) followed by three cycles of docetaxel (100 mg/m 2). Because of an apparent high incidence of side effects, especially febrile neutropenia (FN) and non-hematologic side effects, the DBCG (The Danish Breast Cancer Cooperative Group) initiated a retrospective study of adverse reactions to the newly introduced regime and all patients were offered primary prophylaxis with growth factors (G-CSF) pr 1/1-2008. Material and methods. Two medical doctors examined available journals and nurse charts from the 13 oncology departments in Denmark, and graded all side effects according to NCI CTC version 2.0. To be enrolled, the patients should have received three cycles of EC and at least one cycle of docetaxel. The side effects were investigated before and after routine use of G-CSF. Results. One thousand one hundred and forty-three patients entered the study. In 2007 (before G-CSF) the incidence of FN was 25% and 90.6% of the patients completed the planned treatment. In 2008 (after the introduction of G-CSF) the incidence of FN was 10% and 94.5% completed the treatment. The incidence of non-hematological adverse events, in 2007 and 2008 combined, was for neuropathy 35%, mucositis 75%, muscle and joint pain 53%, skin rash 25% and fatigue 43% (all grades). Conclusion. The introduction of G-CSF was justified because of the high incidence of FN. However, it could not have been predicted after reviewing the published literature. The incidence of non-hematological adverse events had been reported in some, but not all adjuvant taxanes studies. In the future, focus should be more on the side effects, especially when introducing new toxic systemic regimes. © 2011 Informa Healthcare.

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