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Reykjavík, Iceland

Sigurdsson K.,The Icelandic Cancer Detection Clinic | Sigurdsson K.,University of Iceland | Olafsdottir E.J.,The Icelandic Cancer Registry
Breast Cancer: Targets and Therapy | Year: 2013

Objective: This study analyzes the efficacy of the Icelandic population-based service mammography screening. Material and methods: Women aged 40–69 were invited for screening at 2-year intervals starting in November 1987. The study evaluates: (A) attendance and other screened performance parameters during 1998–2010; (B) trends in age-standardized and age-specific incidence rates during 1969–2010 and mortality rates during 1969–2010; and (C) distribution of risk factors and disease specific death rates according to mode of detection. Results: (A) In the age group of 40–69, the average 2-year attendance was 62%, recall rate was 4.1%, needle biopsy rate was 1.3%, surgery rate was 0.6%, invasive cancer rate was 0.4%, and ductal carcinoma in situ (DCIS) rate was 0.06%. (B) The linear incidence trend after the start of screening decreased significantly in the age group 40–49, increased significantly in the age group 50–69, but decreased non-significantly in the age group 70–79. The decreased age-specific incidence in the 70–79 age group was, however, greater than the increased age-specific incidence at the ages 50–69. The mortality rate decreased 41% for all age groups and the linear mortality trend decreased significantly at ages 40–49, 50–69, and 70–79. In the age group 40–74 years, the age-specific mortality decreased by 6.9 cases per 2000 during a 10-year period. (C) Screen-detected women had significantly smaller tumors, more favorable tumor grade, fewer axillary metastases and, after correction for other risk factors, the likelihood of dying from cancer decreased 54% (hazard ratio: 0.46; 95% confidence interval: 0.31–0.69) for these patients compared to cases of nonparticipators. Conclusion: The study results confirm acceptable rates of recalls and referrals for further diagnosis and treatment, and significantly decreased breast cancer mortality rate after starting screening. © 2013 Sigurdsson and Ólafsdóttir, publisher and licensee Dove Medical Press Ltd. Source


Asdahl P.H.,Aarhus University Hospital | Asdahl P.H.,Danish Cancer Society | Winther J.F.,Danish Cancer Society | Bonnesen T.G.,Aarhus University Hospital | And 11 more authors.
International Journal of Cancer | Year: 2016

Survival after childhood cancer diagnosis has remarkably improved, but emerging evidence suggests that cancer-directed therapy may have adverse gastrointestinal late effects. We aimed to comprehensively assess the frequency of gastrointestinal and liver late effects among childhood cancer survivors and compare this frequency with the general population. Our population-based cohort study included all 1-year survivors of childhood and adolescent cancer in Denmark, Finland, Iceland, Norway and Sweden diagnosed from the 1940s and 1950s. Our outcomes of interest were hospitalization rates for gastrointestinal and liver diseases, which were ascertained from national patient registries. We calculated standardized hospitalization rate ratios (RRs) and absolute excess rates comparing hospitalizations of any gastrointestinal or liver disease and for specific disease entities between survivors and the general population. The study included 31,132 survivors and 207,041 comparison subjects. The median follow-up in the hospital registries were 10 years (range: 0–42) with 23% of the survivors being followed at least to the age of 40 years. Overall, survivors had a 60% relative excess of gastrointestinal or liver diseases [RR: 1.6, 95% confidence interval (CI): 1.6–1.7], which corresponds to an absolute excess of 360 (95% CI: 330–390) hospitalizations per 100,000 person-years. Survivors of hepatic tumors, neuroblastoma and leukemia had the highest excess of gastrointestinal and liver diseases. In addition, we observed a relative excess of several specific diseases such as esophageal stricture (RR: 13; 95% CI: 9.2–20) and liver cirrhosis (RR: 2.9; 95% CI: 2.0–4.1). Our findings provide useful information about the breadth and magnitude of late complications among childhood cancer survivors and can be used for generating hypotheses about potential exposures related to these gastrointestinal and liver late effects. © 2016 UICC Source


Stefansson O.A.,University of Iceland | Jonasson J.G.,University of Iceland | Jonasson J.G.,Reykjavik University | Olafsdottir K.,Reykjavik University | And 6 more authors.
Epigenetics | Year: 2011

Triple-negative breast cancer (TNBC) occurs in approximately 15% of all breast cancer patients, and the incidence of TNBC is greatly increased in BRCA1 mutation carriers. This study aimed to assess the impact of BRCA1 promoter methylation with respect to breast cancer subtypes in sporadic disease. Tissue microarrays (TMAs) were constructed representing tumors from 303 patients previously screened for BRCA1 germline mutations, of which a subset of 111 sporadic tumors had previously been analyzed with respect to BRCA1 methylation. Additionally, a set of eight tumors from BRCA1 mutation carriers were included on the TMAs. Expression analysis was performed on TMAs by immunohistochemistry (IHC) for BRCA1, pRb, p16, p53, PTEN, ER, PR, HER2, CK5/6, CK8, CK18, EGFR, MUC1, and Ki-67. Data on BRCA1 aberrations and IHC expression was examined with respect to breast cancer-specific survival. The results demonstrate that CpG island hypermethylation of BRCA1 significantly associates with the basal/triple-negative subtype. Low expression of pRb, and high/intense p16, were associated with BRCA1 promoter hypermethylation, and the same effects were seen in BRCA1 mutated tumors. The expression patterns of BRCA1, pRb, p16 and PTEN were highly correlated, and define a subgroup of TNBCs characterized by BRCA1 aberrations, high Ki-67 (≥ 40%) and favorable disease outcome. In conclusion, our findings demonstrate that epigenetic inactivation of the BRCA1 gene associates with RB/p16 dysfunction in promoting TNBCs. The clinical implications relate to the potential use of targeted treatment based on PARP inhibitors in sporadic TNBCs, wherein CpG island hypermethylation of BRCA1 represents a potential marker of therapeutic response. © 2011 Landes Bioscience. Source


Stefansson O.A.,Bellvitge Biomedical Research Institute | Moran S.,Bellvitge Biomedical Research Institute | Gomez A.,Bellvitge Biomedical Research Institute | Sayols S.,Bellvitge Biomedical Research Institute | And 11 more authors.
Molecular Oncology | Year: 2015

In cancer, epigenetic states are deregulated and thought to be of significance in cancer development and progression. We explored DNA methylation-based signatures in association with breast cancer subtypes to assess their impact on clinical presentation and patient prognosis. DNA methylation was analyzed using Infinium 450K arrays in 40 tumors and 17 normal breast samples, together with DNA copy number changes and subtype-specific markers by tissue microarrays. The identified methylation signatures were validated against a cohort of 212 tumors annotated for breast cancer subtypes by the PAM50 method (The Cancer Genome Atlas). Selected markers were pyrosequenced in an independent validation cohort of 310 tumors and analyzed with respect to survival, clinical stage and grade. The results demonstrate that DNA methylation patterns linked to the luminal-B subtype are characterized by CpG island promoter methylation events. In contrast, a large fraction of basal-like tumors are characterized by hypomethylation events occurring within the gene body. Based on these hallmark signatures, we defined two DNA methylation-based subtypes, Epi-LumB and Epi-Basal, and show that they are associated with unfavorable clinical parameters and reduced survival. Our data show that distinct mechanisms leading to changes in CpG methylation states are operative in different breast cancer subtypes. Importantly, we show that a few selected proxy markers can be used to detect the distinct DNA methylation-based subtypes thereby providing valuable information on disease prognosis. © 2014 The Authors. Source


Torfadottir J.E.,University of Iceland | Valdimarsdottir U.A.,University of Iceland | Valdimarsdottir U.A.,Harvard University | Mucci L.A.,Harvard University | And 17 more authors.
PLoS ONE | Year: 2013

Objective: To examine whether fish and fish oil consumption across the lifespan is associated with a lower risk of prostate cancer. Design: The study was nested among 2268 men aged 67-96 years in the AGES-Reykjavik cohort study. In 2002 to 2006, dietary habits were assessed, for early life, midlife and later life using a validated food frequency questionnaire. Participants were followed for prostate cancer diagnosis and mortality through 2009 via linkage to nationwide cancer- and mortality registers. Adjusting for potential confounders, we used regression models to estimate odds ratios (ORs) and hazard ratios (HRs) for prostate cancer according to fish and fish oil consumption. Results: Among the 2268 men, we ascertained 214 prevalent and 133 incident prostate cancer cases, of which 63 had advanced disease. High fish consumption in early- and midlife was not associated with overall or advanced prostate cancer. High intake of salted or smoked fish was associated with a 2-fold increased risk of advanced prostate cancer both in early life (95% CI: 1.08, 3.62) and in later life (95% CI: 1.04, 5.00). Men consuming fish oil in later life had a lower risk of advanced prostate cancer [HR (95%CI): 0.43 (0.19, 0.95)], no association was found for early life or midlife consumption. Conclusions: Salted or smoked fish may increase risk of advanced prostate cancer, whereas fish oil consumption may be protective against progression of prostate cancer in elderly men. In a setting with very high fish consumption, no association was found between overall fish consumption in early or midlife and prostate cancer risk. © 2013 Torfadottir et al. Source

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