Feasibility of couple-based expanded carrier screening offered by general practitioners.

Expanded carrier screening (ECS) aims to inform couples' reproductive choice, preferably before conception. As part of an implementation study in which trained general practitioners (GPs) offered a population-based ECS couple-test, we evaluated the feasibility of the test-offer and degree of participant informed choice (IC). Trained GPs from nine practices in the northern Netherlands invited 4295 female patients aged 18-40 to take part in couple-based ECS.

Ovarian cancer in BRCA1/2 mutation carriers: The impact of mutation position and family history on the cancer risk.

Objectives: Assessing the combined impact of mutation position, regarding the ovarian cancer cluster region (OCCR), and type of cancer family history (FH) on age-related penetrance of ovarian cancer (OC) in women from BRCA1/2 families from the northern Netherlands.

Study Design: A consecutive series of 1763 mutation carriers and their first-degree relatives from 355 proven BRCA1/2 families with a history of breast and/or ovarian cancer with in total 248 OC cases was included. Mutations were stratified for gene (BRCA1 or BRCA2) and location (within or outside the OCCR).

Maximising the efficiency of clinical screening programmes: balancing predictive genetic testing with a right not to know.

We explored the dilemma between patients' right not to know their genetic status and the efficient use of health-care resources in the form of clinical cancer screening programmes. Currently, in the Netherlands, 50% risk carriers of heritable cancer syndromes who choose not to know their genetic status have access to the same screening programmes as proven mutation carriers. This implies an inefficient use of health-care resources, because half of this group will not carry the familial mutation.

Variation in mutation spectrum partly explains regional differences in the breast cancer risk of female BRCA mutation carriers in the Netherlands.

Background: We aimed to quantify previously observed relatively high cancer risks in BRCA2 mutation carriers (BRCA2 carriers) older than 60 in the Northern Netherlands, and to analyze whether these could be explained by mutation spectrum or population background risk.

Methods: This consecutive cohort study included all known pathogenic BRCA1/2 carriers in the Northern Netherlands (N = 1,050). Carrier and general reference populations were: BRCA1/2 carriers in the rest of the Netherlands (N = 2,013) and the general population in both regions.

Proven non-carriers in BRCA families have an earlier age of onset of breast cancer.

Background: Risk estimates for proven non-carriers in BRCA mutation families are inconsistent for breast cancer and lacking for ovarian cancer. We aimed to assess the age-related risks for breast and ovarian cancer for proven non-carriers in these families.

Methods: A consecutive cohort study ascertained 464 proven non-carriers who had a first-degree relative with a pathogenic BRCA mutation.

Breast Cancer Incidence After Risk-Reducing Salpingo-Oophorectomy in BRCA1 and BRCA2 Mutation Carriers.

Premenopausal risk-reducing salpingo-oophorectomy (RRSO) in BRCA1/2 mutation carriers effectively reduces ovarian cancer risk, but also reduces breast cancer risk. Breast cancer risk reductions up to 50% have been reported for both BRCA1 and BRCA2 mutation carriers, but recent prospective studies were not able to reproduce this finding for BRCA1 mutation carriers. Breast cancer incidence after RRSO was assessed in a consecutive series of 104 BRCA1 and 58 BRCA2 mutation carriers.

Penetrance of breast cancer, ovarian cancer and contralateral breast cancer in BRCA1 and BRCA2 families: high cancer incidence at older age.

Accurate estimations of lifetime risks of breast and ovarian cancer are crucial for counselling women from BRCA1/2 families. We therefore determined breast and ovarian cancer penetrance in BRCA1/2 mutation families in the northern Netherlands and compared them with the incidence of cancers in the general population in this region. We identified 1188 female mutation carriers and first-degree female relatives in 185 families with a pathogenic BRCA1 or BRCA2 mutation.

Selective expression of cholesterol metabolism genes in normal CD34+CD38- cells with a heterogeneous expression pattern in AML cells.

Objective: To identify adenosine triphosphate-binding-cassette (ABC) transporters that are selectively expressed in normal and/or leukemic CD34+CD38- stem cells.

Methods: Microarray experiments on murine stem cells identified 13 ABC transporters with a high expression level. Corresponding human transporters were analyzed in normal CD34+CD38- and CD34+CD38+ bone marrow cells by quantitative reverse transcriptase polymerase chain reaction.

Breast cancer resistance protein (BCRP) in acute leukemia.

Multidrug resistance, cross-resistance to structurally and functionally unrelated drugs, is an important cause of treatment failure in acute leukemia. Multidrug resistance can result from the overexpression of ATP-dependent efflux pumps, such as P-glycoprotein and members of the multidrug resistance associated protein (MRP) family. Recently a novel transporter has been identified, which is called breast cancer resistance protein (BCRP), ABCG2 or mitoxantrone resistance protein.

The role of breast cancer resistance protein in acute lymphoblastic leukemia.

Purpose: Overexpression of the transporter ABCG2, also known as breast cancer resistance protein and mitoxantrone resistance protein, can confer resistance to a variety of cytostatic drugs, such as mitoxantrone, topotecan, doxorubicin, and daunorubicin. This study analyzes the ABCG2 expression and activity in 46 human de novo acute lymphoblastic leukemia B- and T-lineage (ALL) samples.

Experimental Design: ABCG2 expression was measured flow cytometrically with the BXP-34 monoclonal antibody.

High functional P-glycoprotein activity is more often present in T-cell acute lymphoblastic leukaemic cells in adults than in children.

There is a distinct difference in prognosis between childhood versus adult acute lymphoblastic leukaemia (ALL). To define whether multidrug resistance (MDR) genes might contribute to this distinction, the expression and functional activity of P-glycoprotein (P-gp) and MDR associated proteins (MRP) were determined with RT-PCR (MDR-1, MRP1, MRP2, MRP3) and flow cytometry (P-gp and MRP). Patient samples were obtained from 36 children and 35 adults with de novo ALL.

The role of drug efflux pumps in acute myeloid leukemia.

A major problem in the treatment of patients with acute myeloid leukemia (AML) is the occurrence of resistance to structurally and functionally unrelated chemotherapeutic agents, called multidrug resistance (MDR). One of the known MDR mechanisms is the overexpression of adenosine triphosphate (ATP)-dependent efflux pumps. Permeability-glycoprotein (P-gp), the best characterized of the human drug efflux pumps, has been shown to be associated with poor treatment outcome in AML patients.

Expression and activity of breast cancer resistance protein (BCRP) in de novo and relapsed acute myeloid leukemia.

Overexpression of the breast cancer resistance protein (BCRP) efflux pump in human cancer cell lines results in resistance to a variety of cytostatic agents. The aim of this study was to analyze BCRP protein expression and activity in acute myeloid leukemia (AML) samples and to determine whether it is up-regulated due to clonal selection at relapse/refractory disease. BCRP protein expression was measured flow cytometrically with the monoclonal antibodies BXP-34 and BXP-21 in 20 paired samples of de novo and relapsed/refractory AML.