Cryosurgery for recurrent prostate cancer following radiation therapy

Patients with prostate cancer are commonly treated medically or undergo radical prostatectomy and/or radiation therapy. Radiation therapy is usually selected for patients with local or regional disease and patients for whom traditional surgery has failed. The local recurrence of cancer in patients treated with radiation therapy presents a difficult challenge regarding the selection of further treatment options. A commonly applied treatment is salvage prostatectomy, but it can be difficult and complicated, with positive surgical margins occurring in as many as 50 percent of patients and with significant postoperative morbidity. Hormonal therapy, which is not curative, has served as an alternative to surgery in patients who have failed to respond to radiation therapy. Cryosurgery, the destruction of diseased tissue by freezing, is increasingly used both as a first-line therapy and as a second-line therapy (salvage therapy) in patients for whom radiation therapy has failed. Recent reports suggest that cryosurgery may be a useful alternative procedure for treating some of these patients with recurrent cancers. Outcomes of cryosurgery are improving through better instrumentation, surgical technique, and experience. The available data suggest that some patients with radioresistant cancer appear to benefit from the use of cryosurgery as a salvage therapy. Use of this technique has resulted in biochemical disease-free survival for varying periods of some patients who had recurrent prostate carcinoma following radiation therapy; however, morbidity remains high and relatively few patients have had adequate followup. Salvage cryosurgery prospective clinical trials are warranted and would help determine long-term survival benefits and make possible the comparison of cryotherapy patient survival rates with those of untreated biopsy-positive patients.

Utility of current risk stratification tests for predicting major arrhythmic events after myocardial infarction

OBJECTIVES

We surveyed the literature to estimate prediction values for five common tests for risk of major arrhythmic events (MAEs) after myocardial infarction. We then determined feasibility of a staged risk stratification using combinations of noninvasive tests, reserving an electrophysiologic study (EPS) as the final test.

BACKGROUND

Improved approaches are needed for identifying those patients at highest risk for subsequent MAE and candidates for implantable cardioverter-defibrillators.

METHODS

We located 44 reports for which values of MAE incidence and predictive accuracy could be inferred: signal-averaged electrocardiography; heart rate variability; severe ventricular arrhythmia on ambulatory electrocardiography; left ventricular ejection fraction; and EPS. A meta-analysis of reports used receiver-operating characteristic curves to estimate mean values for sensitivity and specificity for each test and 95% confidence limits. We then simulated a clinical situation in which risk was estimated by combining tests in three stages.

RESULTS

Test sensitivities ranged from 42.8% to 62.4%; specificities from 77.4% to 85.8%. A three-stage stratification yielded a low-risk group (80.0% with a two-year MAE risk of 2.9%), a high-risk group (11.8% with a 41.4% risk) and an unstratified group (8.2% with an 8.9% risk equivalent to a two-year incidence of 7.9%).

CONCLUSIONS

Sensitivities and specificities for the five tests were relatively similar. No one test was satisfactory alone for predicting risk. Combinations of tests in stages allowed us to stratify 91.8% of patients as either high-risk or low-risk. These data suggest that a large prospective study to develop a robust prediction model is feasible and desirable.

Dysrhythmia hazard after hospitalization for myocardial infarction: two ECG prognostic methods compared

We retrieved reports of heart rate variability and signal-averaged electrocardiograms (SAECG) used to predict risk of a dysrhythmic event. From each report the number of cases with and without events was extracted to establish accurate values for true positive rate (tpr = sensitivity) and false positive rate (fpr = 1 minus specificity). For all the heart rate variability reports, these values were collected and tpr values were plotted versus fpr. The (fpr,tpr) data were summarized by a meta ROC graph using the method of Moses and Shapiro. A composite weighted mean value and 95% confidence interval were also derived. A summary meta-ROC curve for the SAECG reports was similarly obtained., Meta-ROC analysis of multiple reports better summarizes the performances of different prognostic methods and allows the effect of combining tests for a larger population to be simulated.

Signal-averaged electrocardiography

Signal-averaged electrocardiography (SAECG) is a technique involving computerized analysis of segments of a standard surface electrocardiogram. It is used for detecting small electrical impulses, termed ventricular late potentials, that follow the QRS segment. They are embedded in the electrocardiogram but ordinarily obscured by skeletal muscle activity and other extraneous sources of "noise" encountered in recording a standard electrocardiogram. Ventricular late potentials in patients with cardiac abnormalities, especially coronary artery disease or following an acute myocardial infarction, are associated with an increased risk of ventricular tachyarrhythmias and sudden cardiac death. Proponents of SAECG claim that it can obviate the need for invasive techniques commonly used to identify high-risk patients for interventions that treat or prevent ventricular tachyarrhythmia and sudden death. No randomized clinical trials evaluating SAECG have been completed; data from an ongoing National Institutes of Health-sponsored clinical trial are expected to be available in 3-4 years. The current data on SAECG show relatively consistent high negative predictive values, poor positive predictive values, and variable sensitivity and specificity when the technique is used on patients with cardiomyopathy or following a myocardial infarction. The available evidence also indicates that combining SAECG with other tests of cardiac function is superior to using any single test for risk. The utility of SAECG alone as an indicator of risk remains to be proven. SAECG combined with other standard tests of risk has been demonstrated to have clinical utility in patients following an acute myocardial infarction. Other patient populations have not been conclusively shown to benefit from its use.

Lung-volume reduction surgery for end-stage chronic obstructive pulmonary disease

Lung-volume reduction surgery (LVRS) has been proposed as a palliative treatment for selected patients with diffuse emphysema and end-stage chronic obstructive pulmonary disease who have failed conventional therapy. A number of surgical techniques have been used that are designed to reduce lung volume by surgical resection or laser plication. These techniques are designed to restore previous compromised lung elastic recoil so that expiratory airflow obstruction is reduced, respiratory mechanics are improved, and disabling dyspnea is relieved. Preliminary data derived from both published and unpublished information indicate some favorable short-term benefits. However, objective postoperative data are available for only a small proportion of patients, and long-term followup data are not available. In addition, these surgeries are associated with significant morbidity (and a 6 percent [approximate] surgical mortality) and prolonged hospital stays in a substantial percentage of patients. Patient selection criteria are heterogeneous and in flux, and controversy continues concerning the most appropriate surgical techniques for various categories of patients. The current data do not permit a logical and scientifically defensible conclusion regarding the risks and benefits of LVRS.

Autologous peripheral stem-cell transplantation

Autologous peripheral stem-cell transplantation (APSCT) has been extensively applied to support cancer patients who have undergone high-dose chemotherapy (HDCT) and suffer from the effects of otherwise prolonged or irreversible myelosuppression. The APSCT process involves harvesting of autologous progenitor cells from a patient's circulating blood (via leukapheresis), cryopreservation of the cells, and subsequent intravenous infusion for bone marrow hematopoietic reconstitution (HR). Although pluripotent stem cells, capable of multilineage differentiation, cannot be distinguished by morphologic criteria, they can be characterized as being CD34+ cells capable of indefinite self-renewal in situ and long-term self-renewal in cell cultures. Bone marrow and peripheral blood are common sources of autologous progenitor cells. Current techniques to identify and separate CD34+ cells for use in APSCT have resulted in fewer tumor cells being infused than if unseparated peripheral stem cells (PSC) were transplanted, with no differences noted in HR. Chemotherapy- and cytokine-induced mobilization results in increases in progenitor cells, necessitating fewer phereses to harvest sufficient numbers of progenitor cells for engraftment. This assessment addresses the safety, efficacy, and cost-effectiveness of the use of PSC for HR and improving patient outcome, as well as the indications and criteria for patient selection for the use of APSCT. Available information from study panels, research centers, institutions, and government agencies is reviewed; randomized clinical tests (or lack thereof) are discussed; and comparisons are made between APSCT and autologous bone marrow transplantation (ABMT), an accepted therapy in treatment of some malignancies (e.g., leukemia and lymphoma). The author concludes that existing evidence indicates that PSC can provide satisfactory HR, and the rate of HR via PSC does not seem consistently different from that of ABMT. The clinical importance of HR continues to be secondary to the primary issue of the patient benefits of HDCT in terms of antitumor response, palliation, or survival.

Magnetic resonance angiography: vascular and flow imaging

Magnetic resonance angiography (MRA) techniques are increasingly being used in addition to or in place of conventional x-ray angiography (CA) methods for studies of blood flow and blood vessel morphology. MRA has evolved from magnetic resonance imaging (MRI) techniques for noninvasive visualization of blood flow and vasculature. MRI, aided by computers, generates images (angiograms) created by the contrast of flowing blood and the surrounding tissues; the magnetically depolarized flowing blood contrasts with the magnetically saturated stationary tissues, resulting in a differential high-signal intensity. MRA signals are MRI signals encoded with spatial data achieved by Fourier and echoplanar imaging, projection reconstruction, and spiral scanning. MRA's vasculature "flow map" incorporates both anatomic and physiologic information. This publication explores the history, principles, techniques (including time-of-flight and phase-contrast imaging), clinical applications, and indications and contraindications of MRA use. In addition, data on particular areas of study such as the head and neck and cerebral, thoracic, abdominal, and peripheral vasculature are provided. Two-and three-dimensional MRA methods are discussed, and comparisons are made between MRA and CA. Recommendations from several health service agencies and institutions are provided. Drawbacks, e.g., generally poorer resolution compared with CA, and restrictions of MRA use are discussed. Corollary studies with standard MRI or CA methods are sometimes advisable, and MRA alone is not always sufficient for comprehensive analysis of blood flow and blood vessel vasculature. MRA techniques have been developing in response to the hazards and limitations of CA; MRA involves no exposure to ionizing radiation and generally has a shorter information accrual time compared with conventional scans, in addition to being noninvasive and circumventing the systemic reactions sometimes caused by contrast agents in CA. Another advantage to MRA use is that it can be conducted in an outpatient setting, and many restrictions that apply to CA do not apply to MRA techniques. MRA is useful in detecting aneurysms, occlusions, and stenoses and is especially important in cases in which the use of contrast agents presents high risk. MRA is a promising technology for accurate and noninvasive evaluation of blood flow and blood vessel morphology. Though it cannot at present be considered a standard technique, it is gaining wider acceptance, especially in diagnoses of patients whose condition contraindicates standard angiography.

Protein A columns for the treatment of patients with idiopathic thrombocytopenic purpura and other indications

ECI using protein A columns has been designed to selectively remove circulating CICs and IgG from the plasma of patients in whom these substances are associated with their disease. The use of protein A columns appears to be a reasonable alternative to plasmapheresis in many autoimmune disorders for which plasma exchange is indicated. Although preliminary evidence suggests efficacy of plasma exchange, there is a paucity of data indicating that ECI would indeed provide comparable efficacious results. Although the role of ECI using protein A columns for the treatment of ITP continues to be poorly defined, its use in urgent and life-threatening situations in both ITP and HUS appears reasonable. The results of any treatment for chronic refractory ITP continue to be unsatisfactory. However, favorable responses have been achieved using protein A columns, suggesting the need for further investigation. The role of ECI in the treatment of other disorders, including AIDS, TTP, and the treatment of malignancies, where clinical effects are transient, continues to be investigational. The true clinical response rates and duration of responses to ECI using protein A in treating any disorder requires definition in studies involving a larger number of patients with longer followup. The demonstration of the ultimate clinical value of this therapy will require clinical trials comparing its efficacy to other therapies. Although more serious reactions have been reported, toxicities associated with the use of protein A columns are generally transient and mild.

Apheresis in the treatment of chronic relapsing polyneuropathy

As a distinct inflammatory demyelinating disease, chronic relapsing polyneuropathy can be extremely debilitating and cause respiratory failure leading to death. The cause of the disorder is unknown, although evidence suggests that immune dysfunction plays some role in its pathogenesis. Conventional treatment using steroids and immunosuppressants has been reported both as effective and ineffective in controlling the course of the disease. The rationale for apheresis, as a nonspecific therapy, is related to the removal and/or dilution of circulating cytotoxic factors, and some patients have achieved dramatic and sometimes prolonged remissions from such treatments. Existing evidence from a large and growing number of case reports suggests that apheresis is a reasonable treatment for patients with severe or life-threatening symptoms which fail to respond to conventional therapy. However, convincing data of its efficacy is lacking and must await the results of appropriate randomized clinical trials.

The treatment of lung cancer: perspectives and critique

Future improvements in the therapy of lung cancer most probably will result from new treatment approaches that combine all existing modalities. This paper discusses the applications and, in particular, the shortcomings of present knowledge in surgery, radiotherapy, chemotherapy, immunotherapy, and combinations of these modalities as they relate to the growing problem of treatment in lung cancer.

The limitations of model systems in prostatic cancer

The quest for an ideal model useful for designing treatment strategies as well as providing biological information is not a realistic goal. A multitude of models are required to answer a multiplicity of questions. However, given the currently available treatment modalities much can be accomplished directly in man without resorting to preclinical models.