Browsing Medical Oncology by Subjects
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The clinical effectiveness and cost-effectiveness of genotyping for CYP2D6 for the management of women with breast cancer treated with tamoxifen: a systematic review.Breast cancer is the most common cancer affecting women in the UK. Tamoxifen (TAM) is considered as the standard of care for many women with oestrogen receptor positive breast cancer. However, wide variability in the response of individuals to drugs at the same doses may occur, which may be a result of interindividual genetic differences (pharmacogenetics). TAM is known to be metabolised to its active metabolites N-desmethyl TAM and 4-hydroxytamoxifen by a number of CYP450 enzymes, including CYP2D6, CYP3A4, CYP2C9, CYP2C19 and CYP2B6. N-desmethyl TAM is further metabolised to endoxifen by CYP2D6. Endoxifen, which is also formed via the action of CYP2D6, is 30- to 100-fold more potent than TAM in suppressing oestrogen-dependent cell proliferation, and is considered an entity responsible for significant pharmacological effects of TAM. Thus, an association between the cytochrome P450 2D6 (CYP2D6) genotype and phenotype (expected drug effects) is believed to exist and it has been postulated that CYP2D6 testing may play a role in optimising an individual's adjuvant hormonal treatment.
Effective oral chemotherapy for breast cancer: pillars of strength.Traditionally, anticancer therapy has been dominated by intravenous drug therapy. However, oral agents provide an attractive approach to chemotherapy and use of oral treatments is increasing. We discuss the benefits and challenges of oral chemotherapy from the perspectives of patients, healthcare providers and healthcare funders. Important issues include patient preference, efficacy, compliance, bioavailability, reimbursement, use in special patient populations, financial and staff time savings and flexibility of dosing. We review data for traditional oral agents (e.g. cyclophosphamide, methotrexate), newer oral chemotherapies (e.g. capecitabine), oral formulations of traditionally intravenous agents (e.g. vinorelbine, idarubicin) and new biologic agents under evaluation in breast cancer (e.g. tyrosine kinase inhibitors). Lastly, we review studies of all-oral combination regimens. The wealth of data available and the increasing use of oral agents in breast cancer suggest that many of the concerns and perceptions about oral therapy, including efficacy and bioavailability, have been overcome, and that oral therapy will play a major role in breast cancer management in the future in both the metastatic and adjuvant settings.
Influence of co-morbidity on renal function assessment by Cockcroft-Gault calculation in lung cancer and mesothelioma patients receiving platinum-based chemotherapy.Creatinine clearance (CrCl) estimation by Cockcroft-Gault calculation (CG) often replaces measurement of glomerular filtration rate (GFR) by [(51)Cr]-ethylenediaminetetraacetic acid clearance (EDTA). Co-morbidity, age, and renal impairment influence the accuracy of CG, whilst the relationship between CG and EDTA has been poorly assessed in lung cancer patients, a population significantly affected by these covariates.
Multiplexed assays for detection of mutations in PIK3CA.BACKGROUND: Mutations in the PIK3CA gene (phosphoinositide-3-kinase, catalytic, alpha polypeptide) have recently been described in a number of cancers, and their detection is currently limited because of the low sensitivity of conventional sequencing techniques. METHODS: We combined Amplification Refractory Mutation System (ARMS; AstraZeneca) allele-specific PCR and Scorpions (DxS) to develop assays for tumor-borne PIK3CA mutations and used real-time PCR to develop high-throughput multiplexed assays for the most commonly reported PIK3CA mutants (H1047L, H1047R, E542K, E545K). RESULTS: These assays were more sensitive than sequencing and could detect 5 copies of mutant DNA in proportions as low as 0.1% of the total DNA. We assayed DNA extracted from human tumors and detected PIK3CA mutation frequencies of 10.2% in colorectal cancer, 38.7% in breast cancer, 1.9% in lung cancer, and 2.9% in melanoma. In contrast, sequencing detected only 53% of the mutations detected by our assay. CONCLUSIONS: Multiplexed assays, which can easily be applied to clinical samples, have been developed for the detection of PIK3CA mutations.