Determination of tissue optical properties is fundamental for application of light in either therapeutical or diagnostics procedures. In the present work we implemented a spatially resolved steady-state diffuse reflectance method where only two fibers (one source and one detector) spaced 2.5 mm apart are used for the determination of the optical properties. The method relies on the spectral characteristics of the tissue chromophores (water, dry tissue, and blood) and the assumption of a simple wavelength dependent expression for the determination of the reduced scattering coefficient. Because of the probe dimensions the method is suited for endoscopic measurements. The method was validated against more traditional models, such as the diffusion theory combined with adding doubling for in vitro measurements of bovine muscle. Mean and standard deviation of the absorption coefficient and the reduced scattering coefficient at 630 nm for normal mucosa were 0.87±0.22 cm–1 and 7.8±2.3 cm–1, respectively. Cancerous mucosa had values 1.87±1.10 cm–1 and 8.4±2.3 cm–1, respectively. These values are similar to data presented by other authors. Blood perfusion was the main variable accounting for differences in the absorption coefficient between the studied tissues.
Background: Subjective measures are considered the gold standard in palliative care evaluation, but no studies have evaluated palliative photodynamic therapy (PDT) subjectively. If PDT is to be accepted as a palliative therapy for later-stage obstructing esophageal and lung cancer, evidence of its effectiveness and acceptability to patients must be made known. Study Design/Materials and Methods: This ongoing study's major aim is to evaluate subjective outcomes of PDT in patients with obstructing esophageal and lung cancer. Existing measures of health status, dysphagia and performance status were supplemented with an instrument developed to evaluate PDT symptom relief and side effect burden, the PDT Side Effects Survey (PSES). Results: PDT patients treated with porfimer sodium (Photofrin) and 630-nm light experienced reduced dysphagia grade and stable performance status for at least one month after PDT (N= 10-17), but these effects did not necessarily persist at three months. Fatigue, appetite and quality of life may be the most burdensome issues for these patients. Conclusions: Preliminary data suggest that the PSES is an acceptable and valid tool for measuring subjective outcomes of palliative PDT. This study is the first attempt to systematically evaluate subjective outcomes of palliative PDT. Multi-center outcomes research is needed to draw generalizable conclusions that will establish PDT's effectiveness in actual clinical practice and enhance the wider adoption of PDT as a cancer symptom relief modality.
Efficacy studies are required for regulatory approval of new medical treatments in the United States and elsewhere. Although efficacy studies may demonstrate safety and efficacy, they are not always sufficient for characterizing the effects of a treatment in actual clinical practice. Ongoing outcomes research is necessary to identify outcomes of treatment and treatment patterns in actual clinical practice. Criteria for evaluating palliative treatments in outcomes research must reflect the treatment's capacity to relieve symptoms while entailing minimal risks and adverse effects. However, the measurement of symptom relief as a result of treatment is prone to error because symptoms are inherently subjective and may be influenced by a variety ofnon-treatment factors, such as individual perception, physical exertion, and concurrent symptom management strategies. PDT patients treated with Photofrin® and 630-nm light at our center have had reduced dysphagia grade and stable performance status for approximately one month after PDT (N= 7-26), but these effects did not necessarily persist at the three-month followup interval. Preliminary data on five patients collected in a pilot study of a new symptom burden measurement tool suggest that the perceived burden ofphotosensitivity may increase with time. Fatigue, poor appetite and decreased overall quality of life appear to be the most troubling symptoms for our late-stage esophageal cancer PDT patients. The least burdensome symptoms were anxiety, pain and depression.
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