PubMed · 7879401
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E Ernst. 1994. [Mechanotherapy].. https://pubmed.ncbi.nlm.nih.gov/7879401/
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PURPOSE: Methods of performing dosimetry for a combined modality radiotherapy (CMRT) consisting of a targeted radionuclide therapy (TRT) and separately delivered external beam therapy (EBT) have been established using the biologically effective dose (BED). However, a concurrent delivery of the two therapies may influence the radiobiologic effect of the treatment resulting from interaction between the therapies, and this situation has been modeled to assess the likely consequences of this regime. METHODS AND MATERIALS: A general form of the linear-quadratic model with a dose protraction factor was applied to concurrent delivery of EBT and TRT. Contributions to total BED from intra- and intermodality effects were calculated, and parameter values varied to determine conditions under which the intermodality contributions were likely to be most significant. A Poisson model of tumor control probability (TCP) was used to assess the predicted effect of concurrent delivery on treatment outcome. RESULTS: In general, over a wide range of parameter values, the effect of intermodality interactions in CMRT is small, increasing total BED delivered to tumor by approximately 1%, and producing a negligible increase in TCP. Synergistic effects could be greater in normal tissues if high doses were received from both therapies, with intermodality terms increasing total BED delivered by approximately 6% in the general case, and by approximately 18% for the case of slow repair in the spinal cord. A significant synergistic effect was predicted between EBT and I-125 seed therapy of the prostate when values of alpha/beta = 1.2 Gy, alpha = 0.026 Gy, mu = 0.36 h(-1) and N(0) = 138 clonogens were used, with TCP increasing from approximately 0.5 to 0.6. CONCLUSIONS: Under most clinical conditions, the relative temporal delivery of these two therapies is unlikely to significantly influence the overall radiobiologic effect to tumor at the cellular level. Synergistic effects may, however, be more significant in normal tissues and for tumors with low values of alpha/beta and alpha.
BACKGROUND: Stent thrombosis (ST) is a rare but devastating complication of coronary stent implantation, occurring in 0.5% to 1.9% of patients with bare metal stents. The incidence of ST with drug-eluting stents is less well studied, particularly among patients outside of clinical trials. METHODS AND RESULTS: The aim of this study was to evaluate the incidence and potential risk factors for ST in patients receiving sirolimus-eluting stents (SES) in the "real world" after commercial release in the United States in April 2003. All 652 patients who underwent SES implantation (776 lesions treated) at our institution between April and October 2003 were followed up prospectively after the procedure (median follow-up 100 days). During that period, 7 patients (1.1%, 95% CI 0.4% to 2.2%) developed ST within a range of 2 to 13 days, and 1 patient had an ST-elevation myocardial infarction on day 39 with evidence of thrombus within the SES at angiography. Patients with an ST had significantly smaller final nominal balloon diameters (2.75 versus 3.00 mm, P=0.04), and in 4 (57%) of the 7 patients with ST versus 1.7% of patients without ST (P<0.001), antiplatelet therapy had been discontinued after the procedure. Among the ST patients, 1 died and 5 had myocardial infarctions. CONCLUSIONS: In this single-center experience, the incidence of ST after SES implantation was approximately 1%, which is within the expected range of bare metal stents. The discontinuation of antiplatelet therapy was strongly associated with the development of ST in this patient population.
BACKGROUND: The safety and efficacy of the slow-release, polymer-based, paclitaxel-eluting stent after implantation in a broad cross section of de novo coronary lesions at 1 year are unknown. METHODS AND RESULTS: In the TAXUS-IV trial, 1314 patients with single de novo coronary lesions 10 to 28 mm in length, with reference-vessel diameter 2.5 to 3.75 mm, coverable by a single study stent, were prospectively randomized to the slow-release, polymer-based, paclitaxel-eluting TAXUS stent or an identical-appearing bare-metal EXPRESS stent. By actuarial analysis, the TAXUS stent compared with the bare-metal stent reduced the 12-month rates of target-lesion revascularization by 73% (4.4% versus 15.1%, P<0.0001), target-vessel revascularization by 62% (7.1% versus 17.1%, P<0.0001), target-vessel failure by 52% (10.0% versus 19.4%, P<0.0001), and composite major adverse cardiac events by 49% (10.8% versus 20.0%, P<0.0001). The 1-year rates of cardiac death (1.4% versus 1.3%), myocardial infarction (3.5% versus 4.7%), and subacute thrombosis (0.6% versus 0.8%) were similar between the paclitaxel-eluting and control stents, respectively. Between 9 and 12 months, there were significantly fewer myocardial infarctions (0% versus 1.1%, P=0.007), target-vessel revascularizations (2.4% versus 5.8%, P=0.002), and major adverse cardiac events (2.4% versus 6.3%, P=0.0009) in the paclitaxel-eluting stent than in the control stent group, respectively. CONCLUSIONS: The relative efficacy reported at 9 months for the polymer-based, paclitaxel-eluting TAXUS stent compared with the EXPRESS stent is preserved and continues to increase at 1 year, with no safety concerns apparent.