Cost-Effectiveness of Letrozole in the Extended Adjuvant Treatment of Women with Early Breast Cancer

Adjuvant tamoxifen therapy for 5 years reduces recurrence in hormone receptor positive, post-menopausal women with early breast cancer, but offers no advantage when prolonged to another 5 years, during which the risk of recurrence remains high. Treating patients, who remain disease-free after 5 years of tamoxifen, with letrozole significantly reduces recurrence, regardless of nodal status. This study evaluated the life-time cost-utility of extended adjuvant letrozole therapy in 62-year-old patients from a third-party payer perspective. A Markov model incorporated locoregional, contralateral, and metastatic recurrences. The comparator was placebo. Event rates were based on published trials. Utility values were taken from a clinical trial and published literature. Costs were obtained from published literature, provincial payment schedules, cancer agencies, and drug plans formularies. Resource use reflected Canadian treatment patterns. Robustness of the model was tested using deterministic and probabilistic sensitivity analyses. Extended adjuvant letrozole therapy of a cohort consisting of 50% node-negative and 50% node-positive patients prolonged their lives on average by 0.466 years or 0.267 quality-adjusted life years (QALYs) at an additional cost of Can$8,031 per patient, yielding an incremental cost-utility ratio (ICUR) of $34,058 per QALY. Letrozole was more cost-effective in node-positive than in node-negative patients (Can$26,553 vs Can$46,049 per QALY). Results were robust to variations in age, healthcare costs, and utilities. The degree of confidence that the cost per QALY would be below Can$50,000 reached 100% for node-positive and 77% for node-negative patients. Extended adjuvant letrozole is cost-effective in both node-negative and node-positive patients having ICURs below Can$50,000/QALY.

Transbilayer lipid redistribution accompanies poly(ethylene glycol) treatment of model membranes but is not induced by fusion

Small, unilamellar vesicles (SUV) or large, unilamellar vesicles (LUV) containing a small amount of N-(7-nitro-2,1,3-benzoxadiazol-4-yl)phosphatidylethanolamine (NBD-PE) or the corresponding phosphatidylserine (NBD-PS) were made asymmetric in labeled lipid by reduction of outer leaflet probe with externally added sodium dithionite. Following removal of dithionite, transbilayer lipid redistribution (presumably due to lipid flip-flop) was indicated by a loss of fluorescence intensity upon readdition of dithionite. Vesicle rupture and fusion in the presence of PEG were measured by changes in the fluorescence of trapped Tb3+ complexed with dipicolinic acid (DPA) or by the increase of fluorescence from 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) coencapsulated with a quenching agent. NBD-PE redistributed slowly (approximately 2%/h) in all symmetrically labeled vesicles examined, while NBD-PS did not. NBD-PE redistribution was not accelerated by treatment of vesicles with PEG below concentrations that induced vesicle rupture or fusion, but was enhanced at or above these PEG concentrations. SUV prepared from hen egg yolk phosphatidylcholine (egg PC) or from dioleoylphosphatidylcholine (DOPC)/dilinolenoylphosphatidylcholine (diC(18:3)PC) (85/15) mixtures were shown to fuse without rupturing in the presence of appropriate concentrations of PEG. Matching the osmolalities inside and outside the vesicle mitigated against rupture but did not prevent fusion. Under these conditions, NBD-PE flip-flop was proportional to the amount of fusion, but with different proportionality constants for the two lipid systems, while NBD-PS flip-flop did not occur. Redistribution of total mass from the outer to the inner leaflet during the fusion process could be detected in terms of a change in the ratio of dithionite-reducible probe to total probe. Both probes detected inwardly directed redistribution of lipid mass under conditions that induced fusion of SUV. We conclude that inward mass redistribution must accompany PEG-mediated SUV fusion, but that lipid flip-flop is not mechanistically related to the fusion process.

Noncardiac operations after coronary revascularization

In 35 patients who had had earlier myocardial revascularization, a total of 44 noncardiac operations under general or spinal anesthesia were carried out. There was one cardiac death and three postoperative complications. Compared with the risk of general anesthesia and noncardiac surgical procedures in patients with coronary artery disease who have not had coronary revascularization, this is a major improvement. We conclude that myocardial revascularization provides significant protection against the risk of cardiac complications and death for patients with ischemic heart disease in whom general anesthesia and noncardiac procedures are needed.