Painful bone metastasis in elderly treated with radiation therapy: Single- or multiple-fraction regimen? A multicentre retrospective observational analysis.

BACKGROUND: Bone metastases are a frequent complication of advanced oncologic disease. Pain associated to bone metastasis is a major cause of morbidity in cancer patients, especially in elderly. AIMS: The aim of this multicentric retrospective observational study is to evaluate the efficacy of different schedules of radiation therapy in elderly patients in terms of pain relief. METHODS: 206 patients over the age of 60 were enrolled in 1 year time for a multicentre retrospective observational study. Patients were treated with palliative purposes for painful bone metastases. RESULTS: Pain intensity difference (PID) was found in 72% of patients. Reported PID was statistically significant for p < 0.01. Pain intensity measured by a point numeric rating scale was statistically significant reduced for p < 0.05 by one-fraction regimen compared to other two regimens. DISCUSSION: In recent years, numerous studies have evaluated the most appropriate regimen of fractionation in individual cases, despite this, a consensus about the best schedule is still debated. CONCLUSIONS: On our analysis, single-fractionation scheme (8 Gy) confirmed to be statistical significant effective in providing pain reduction due to bone metastases. Radiation therapy provides significant pain relief of symptomatic bone metastases, but appropriate radiotherapy scheduled is needed in order to get significant response to treatment. Multidisciplinary approach is warranted to value the balance between the therapeutic objectives and the patient quality of life.

History, Epidemic Evolution, and Model Burn-In for a Network of Annual Invasion: Soybean Rust.

Ecological history may be an important driver of epidemics and disease emergence. We evaluated the role of history and two related concepts, the evolution of epidemics and the burn-in period required for fitting a model to epidemic observations, for the U.S. soybean rust epidemic (caused by Phakopsora pachyrhizi). This disease allows evaluation of replicate epidemics because the pathogen reinvades the United States each year. We used a new maximum likelihood estimation approach for fitting the network model based on observed U.S. epidemics. We evaluated the model burn-in period by comparing model fit based on each combination of other years of observation. When the miss error rates were weighted by 0.9 and false alarm error rates by 0.1, the mean error rate did decline, for most years, as more years were used to construct models. Models based on observations in years closer in time to the season being estimated gave lower miss error rates for later epidemic years. The weighted mean error rate was lower in backcasting than in forecasting, reflecting how the epidemic had evolved. Ongoing epidemic evolution, and potential model failure, can occur because of changes in climate, host resistance and spatial patterns, or pathogen evolution.

A stochastic model for cell debris in flow cytometry.

An important problem in analyzing flow cytometry DNA measurements, especially for tumor samples, is the presence of background noise, mainly resulting from cellular debris. Several models have been proposed for subtracting this contribution from DNA content histograms. In the present paper we propose a model for background debris distribution based on a specific mechanism for the DNA fragmentation process of the cell nucleus. In particular, we suggest that the fragmentation is more likely to occur in the sites which are closer to the end points of the DNA chain. This accounts for the observed higher frequency of small-sized fragments in experimental DNA distribution. The proposed model depends on two parameters describing the intensity and the shape of the background. It has been successfully validated against four series of experimental data of DNA distribution with increasing level of background.