Quantifying expert opinion with discrete choice models: Invasive elodea's influence on Alaska salmonids

Scientific evidence should inform environmental policy, but rapid environmental change brings high ecological uncertainty and associated barriers to the science-management dialogue. Biological invasions of aquatic plants are a worldwide problem with uncertain ecological and economic consequences. We demonstrate that the discrete choice method (DCM) can serve as a structured expert elicitation alternative to quantify expert opinion across a range of possible but uncertain environmental outcomes. DCM is widely applied in the social sciences to better understand and predict human preferences and trade-offs. Here we apply it to Alaska's first submersed invasive aquatic freshwater plant, Elodea spp. (elodea), and its unknown effects on salmonids. While little is known about interactions between elodea and salmonids, ecological research suggests that aquatic plant invasions can have positive and negative, as well as direct and indirect, effects on fish. We use DCM to design hypothetical salmonid habitat scenarios describing elodea's possible effect on critical environmental conditions for salmonids: prey abundance, dissolved oxygen, and vegetation cover. We then observe how experts choose between scenarios that they believe could support persistent salmonid populations in elodea-invaded salmonid habitat. We quantify the relative importance of habitat characteristics that influence expert choice and investigate how experts trade off between habitat characteristics. We take advantage of Bayesian techniques to estimate discrete choice models for individual experts and to simulate expert opinion for specific environmental management situations. We discuss possible applications and advantages of the DCM approach for expert elicitation in the ecological context. We end with methodological questions for future research

High dose rate endobronchial brachytherapy in the management of primary and recurrent bronchogenic malignancies

Background. The clinical, radiographic, and bronchoscopic records of patients treated with out‐patient high dose rate (HDR) endobronchial brachytherapy were reviewed to determine its effectiveness in patients with malignant airway obstruction (with or without prior external beam radiation). In addition, quality of life and acute and chronic morbidity were evaluated. Methods. From January 1, 1989 to June 30, 1993, 46 patients received 128 HDR endobronchial treatments employing a high activity Ir‐192 source with a remote afterloader. Patients treated had a total of 22 primary and 17 recurrent bronchogenic carcinomas, 7 of which were metastatic nonpulmonary tumors. Three separate fractions of 7.0 Gy were prescribed to a depth of 1.0 cm. and given 1 week apart. Twelve patients (30%) received prior external beam irradiation (median dose, 58 Gy). Results. Median follow‐up for the entire group was 5 months (17.5 for surviving patients). Of the eight asymptomatic patients, five (62%) remained asymptomatic for the remainder of their lives. Of the 38 symptomatic patients, 28 (74%) had significant clinical improvement, and 12 of them remained improved for the duration of their lives. Of thirty‐six (78%) patients examined for radio‐graphic response, 25 (69%) had a partial or complete response to this treatment. In patients without prior irradiation, there was a tendency for a higher percentage of clinical and radiographic response. Two patients (4%) experienced mild, transient dysphagia, four patients developed self‐limited radiation pneumonitis (9%), and three patients (7%) suffered fatal hemoptysis (all of these patients received prior or concurrent external beam radiotherapy). No factor (i.e., prior radiation therapy, number of catheters placed, surgery, or chemotherapy) predicted an increased risk of complications (P = NS). Conclusions. Outpatient HDR endobronchial brachytherapy is effective in both preventing and relieving endobronchial obstruction in patients with or without prior irradiation, recurrent lesions, or metastatic nonpulmonary disease. A significant proportion of patients can be rendered asymptomatic for the duration of their lives, hence were provided with improved quality of life. These treatments are well tolerated and safe, and result in minimal long term morbidity

Low-dose-rate brachytherapy as the sole radiation modality in the management of patients with early-stage breast cancer treated with breast-conserving therapy: Preliminary results of a pilot trial

Purpose : We present the preliminary findings of our in-house protocol treating the tumor bed alone after lumpectomy with low-dose rate (LDR) interstitial brachytherapy in selected patients with early-stage breast cancer treated with breast-conserving therapy (BCT). Methods and Materials : Since March 1, 1993, 60 women with early-stage breast cancer were entered into a protocol of tumor bed irradiation only using an interstial LDR implant with iodine-125. Patients were eligible if the tumor was ≤3 cm, margins were ≥2 mm, there was no extensive intraductal component, the axilla was template either at the time of reexcision or shortly after lumpectomy. A total of 50 Gy was delivered at 0.52 Gy/h over a period of 96 h to the lumpectomy bed plus a 2-cm margin. Perioperative complications, cosmetic outcome, and local control were assessed. Results : The median follow-up for all patients is 20 months. Three patients experienced minimal perioperative pain that required temporary nonnarcotic analgesics. There have been four postoperative inections which resolved with oral antibiotics. No significant skin reactions related to the implant were noted and no patients experienced impaired would healing. Early cosmetic results reveal minimal changes consisting of transient hyperpigmentation of the skin at the puncture sites and temporary induration in the tumor bed. Good to excellent cosmetic results were noted in all 19 patients followed up a minimum of 24 mounts posttherapy. To date, 51 women have obtained 6–12-month follow-up mammograms and no recurrences have been noted. All patients currently have no physical signs of recurrence, and no patient has failed regionally or distantly. Conclusion : Treatment of the tumor bed alone with LDR interstitial brachytherapy appears to be well tolerated, and early results are promising. Long-term follow-up of these pateints is necessary to establish the equivalence of this treatment approach compared to standard BCT, however