Publications by authors named "Flora van Leeuwen"

Purpose: To evaluate the prevalence and severity of clinical adverse events (AEs) and treatment-related risk factors in childhood cancer survivors treated with cranial radiation therapy (CRT), with the aim of assessing dose-effect relationships.

Methods And Materials: The retrospective study cohort consisted of 1362 Dutch childhood cancer survivors, of whom 285 were treated with CRT delivered as brain irradiation (BI), as part of craniospinal irradiation (CSI), and as total body irradiation (TBI). Individual CRT doses were converted into the equivalent dose in 2-Gy fractions (EQD(2)).

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Background: Advances in childhood cancer treatment over the past decades have significantly improved survival, resulting in a rapidly growing group of survivors. However, both chemo- and radiotherapy may adversely affect reproductive function. This paper describes the design and encountered methodological challenges of a nationwide study in the Netherlands investigating the effects of treatment on reproductive function, ovarian reserve, premature menopause and pregnancy outcomes in female childhood cancer survivors (CCS), the DCOG LATER-VEVO study.

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Background And Objectives: Little is known about renal function and blood pressure (BP) in long-term childhood cancer survivors. This cross-sectional study evaluated prevalence of these outcomes and associated risk factors in long-term childhood cancer survivors at their first visit to a specialized outpatient clinic.

Design, Setting, Participants, & Measurements: Estimated GFR; percentages of patients with albuminuria, hypomagnesemia, and hypophosphatemia; and BP were assessed in 1442 survivors ≥5 years after diagnosis.

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Introduction: Tamoxifen is an effective treatment for breast cancer but an undesirable side-effect is an increased risk of endometrial cancer, particularly rare tumor types associated with poor prognosis. We investigated whether tamoxifen therapy increases mortality among breast cancer patients subsequently diagnosed with endometrial cancer.

Methods: We pooled case-patient data from the three largest case-control studies of tamoxifen in relation to endometrial cancer after breast cancer (1,875 patients: Netherlands, 765; United Kingdom, 786; United States, 324) and collected follow-up information on vital status.

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The Dutch Cancer Society developed the 'KWF Kanker Risico Test' (Cancer Risk Test) to improve the information available to the Dutch population regarding cancer risk factors. This Internet test, based under licence on the American 'Your Disease Risk' test, informs users about risk factors for 12 common types of cancer. The test provides an estimate of individual risk of a specific type of cancer and gives specific lifestyle advice that could lower that risk.

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Recent genome-wide association studies identified 11 single nucleotide polymorphisms (SNPs) associated with breast cancer (BC) risk. We investigated these and 62 other SNPs for their prognostic relevance. Confirmed BC risk SNPs rs17468277 (CASP8), rs1982073 (TGFB1), rs2981582 (FGFR2), rs13281615 (8q24), rs3817198 (LSP1), rs889312 (MAP3K1), rs3803662 (TOX3), rs13387042 (2q35), rs4973768 (SLC4A7), rs6504950 (COX11) and rs10941679 (5p12) were genotyped for 25 853 BC patients with the available follow-up; 62 other SNPs, which have been suggested as BC risk SNPs by a GWAS or as candidate SNPs from individual studies, were genotyped for replication purposes in subsets of these patients.

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Purpose: To evaluate the long-term risk for validated symptomatic cardiac events (CEs) and associated risk factors in childhood cancer survivors (CCSs).

Patients And Methods: We determined CEs grade 3 or higher: congestive heart failure (CHF), cardiac ischemia, valvular disease, arrhythmia and/or pericarditis (according to Common Terminology Criteria for Adverse Events [CTCAE], version 3.0) in a hospital-based cohort of 1,362 5-year CCSs diagnosed between 1966 and 1996.

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Background: Genome-wide association studies (GWAS) identified variants at 19p13.1 and ZNF365 (10q21.2) as risk factors for breast cancer among BRCA1 and BRCA2 mutation carriers, respectively.

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Germline mutations in BRCA1 and BRCA2 are associated with increased risks of breast and ovarian cancer. A genome-wide association study (GWAS) identified six alleles associated with risk of ovarian cancer for women in the general population. We evaluated four of these loci as potential modifiers of ovarian cancer risk for BRCA1 and BRCA2 mutation carriers.

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Survivors of hereditary retinoblastoma have a high risk of second primary malignancies, but it has not been investigated whether specific RB1 germline mutations are associated with greater risk of second primary malignancies in a large cohort. We conducted a retrospective cohort study of 199 survivors of hereditary retinoblastoma with a documented RB1 germline mutation diagnosed between 1905 and 2005. In total, 44 hereditary retinoblastoma survivors developed a second primary malignancy after a median follow-up of 30.

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Women treated at young ages with supradiaphragmatic radiotherapy for Hodgkin lymphoma (HL) have a highly increased risk of breast cancer. For personalized advice and follow-up regimens for patients, information is needed on how the radiotherapy-related risk is affected by other breast cancer risk factors. Genome-wide association studies have identified 14 independently replicated common single nucleotide polymorphisms that influence breast cancer risk.

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Background And Purpose: It has been established that radiotherapy can increase cardiovascular disease (CVD) risk. Genetic variants, which play a role in the tissue, damage response and angiogenesis regulating TGFβ pathway might give us insight into the mechanisms underlying radiation-induced CVD. We examined the effects of two polymorphisms, TGFβ1 29C>T and PAI-1 5G>4G, on CVD incidence.

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Designing a study focused on adverse health-related outcomes among cancer survivors is complex. Similarly, reading and interpreting the findings of a survivorship-focused study requires an appreciation of the complexities of study design, potential biases, confounding factors, and other limitations. The topic areas are broad--study design, comparison populations, measures of risk, key health outcomes of interest, potential modifying factors to consider.

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Background: Web-based questionnaires have become increasingly popular in health research. However, reported response rates vary and response bias may be introduced.

Objective: The aim of this study was to evaluate whether sending a mixed invitation (paper-based together with Web-based questionnaire) rather than a Web-only invitation (Web-based questionnaire only) results in higher response and participation rates for female childhood cancer survivors filling out a questionnaire on fertility issues.

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We sought to compare the molecular signature of node negative cancers from two cohorts 15 years apart, to determine if there is molecular evidence of increase in low and ultralow risk cancers over time. We studied the impact of age, time period of diagnosis, and mammographic screening on biology of tumors where The Netherlands Cancer Institute 70-gene prognosis signature was generated as part of 2 validation series, one retrospective (1984-1992), Cohort 1, and one prospective (2004-2006), Cohort 2. A total of 866 patients were analyzed.

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Objectives: We assessed accuracy of self-reported lifetime mammography history by BRCA1/2 mutation carriers with and without breast cancer.

Study Design And Setting: Within the framework of the HEBON study (The Netherlands Collaborative Group on Hereditary Breast Cancer), 218 Dutch BRCA1/2 mutation carriers had completed a risk factor questionnaire between 2006 and 2007. Accuracy of self-reported lifetime mammography history was assessed by medical record review and calculated by proportion agreement and Cohen's kappa coefficient (κ).

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The Health Council of the Netherlands (HCN) and other organisations hold the basic assumption that induced electric current and the generation and absorption of heat in biological material caused by radiofrequency electromagnetic fields are the only causal effects with possible adverse consequences for human health that have been scientifically established to date. Hence, the exposure guidelines for the 10 MHz-10 GHz frequency range are based on avoiding adverse effects of increased temperatures that may occur of the entire human body at a specific absorption rate (SAR) level above 4 W/kg. During the workshop on Thermal Aspects of Radio Frequency Exposure on 11-12 January 2010 in Gaithersburg, Maryland, USA, the question was raised whether there would be a practical advantage in shifting from expressing the exposure limits in SAR to expressing them in terms of a maximum allowable temperature increase.

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Background: Mammographic screening has led to a proportional shift toward earlier-stage breast cancers at presentation. We assessed whether the method of detection provides prognostic information above and beyond standard prognostic factors and investigated the accuracy of predicted overall and breast cancer-specific survival by the computer tool Adjuvant! among patients with screen-detected, interval, and nonscreening-related carcinomas.

Methods: We studied 2592 patients with invasive breast cancer who were treated at the Netherlands Cancer Institute from January 1, 1990, through December 31, 2000.

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Background: Previous studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors.

Methods: We pooled tumor marker and epidemiological risk factor data from 35,568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies.

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To identify susceptibility loci for classical Hodgkin's lymphoma (cHL), we conducted a genome-wide association study of 589 individuals with cHL (cases) and 5,199 controls with validation in four independent samples totaling 2,057 cases and 3,416 controls. We identified three new susceptibility loci at 2p16.1 (rs1432295, REL, odds ratio (OR) = 1.

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Background: The genes caspase-8 (CASP8) and caspase-10 (CASP10) functionally cooperate and play a key role in the initiation of apoptosis. Suppression of apoptosis is one of the major mechanisms underlying the origin and progression of cancer. Previous case-control studies have indicated that the polymorphisms CASP8 D302H and CASP10 V410I are associated with a reduced risk of breast cancer in the general population.

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Background: Truncating mutations in ATM have been shown to increase the risk of breast cancer but the effect of missense variants remains contentious.

Methods: We have genotyped five polymorphic (minor allele frequency, 0.9-2.

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Background: High Plasminogen-Activator Inhibitor 1 (PAI-1) expression by tumors has been associated with poor prognosis in several cancer types, and high systemic PAI-1 levels with increased thrombosis risk. The authors investigated whether the germline 4G/5G deletion/insertion polymorphism in the PAI-1 promoter (rs1799889), which may influence PAI-1 expression, is associated with survival and chemotherapy-related vascular toxicity in testicular cancer (TC).

Methods: Data were collected on PAI-1 4G/5G polymorphism, survival, venous thromboembolism (VTE), and coronary heart disease (CHD) for 324 non-seminomatous TC patients treated with platinum-based chemotherapy.

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Obesity is an established risk factor for postmenopausal breast cancer in the general population. However, it is still unclear whether this association also exists in BRCA1/2 mutation carriers. We investigated the association between self-reported anthropometric measures and breast cancer risk in a nationwide retrospective cohort study, including 719 BRCA1/2 carriers, of whom 218 had been diagnosed with breast cancer within 10 years prior to questionnaire completion.

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