Accuracy of optical spectroscopy for the detection of cervical intraepithelial neoplasia without colposcopic tissue information; a step toward automation for low resource settings

Optical spectroscopy has been proposed as an accurate and low-cost alternative for detection of cervical intraepithelial neoplasia. We previously published an algorithm using optical spectroscopy as an adjunct to colposcopy and found good accuracy (sensitivity ¼ 1.00 [95% confidence interval ðCIÞ ¼ 0.92 to 1.00], specificity ¼ 0.71 [95% CI ¼ 0.62 to 0.79]). Those results used measurements taken by expert colposcopists as well as the colposcopy diagnosis. In this study, we trained and tested an algorithm for the detection of cervical intraepithelial neoplasia (i.e., identifying those patients who had histology reading CIN 2 or worse) that did not include the colposcopic diagnosis. Furthermore, we explored the interaction between spectroscopy and colposcopy, examining the importance of probe placement expertise. The colposcopic diagnosis-independent spectroscopy algorithm had a sensitivity of 0.98 (95% CI ¼ 0.89 to 1.00) and a specificity of 0.62 (95% CI ¼ 0.52 to 0.71). The difference in the partial area under the ROC curves between spectroscopy with and without the colposcopic diagnosis was statistically significant at the patient level (p ¼ 0.05) but not the site level (p ¼ 0.13). The results suggest that the device has high accuracy over a wide range of provider accuracy and hence could plausibly be implemented by providers with limited training

Inverse decision theory with medical applications

Medical decision makers would like to use decision theory to determine optimal treatment strategies for patients, but it can be very difficult to specify loss functions in the medical setting, especially when trying to assign monetary value to health outcomes. These issues led to the development of an alternative approach, called Inverse Decision Theory (IDT), in which given a probability model and a specific decision rule, we determine the set of losses for which that decision rule is optimal. This thesis presents the evolution of the IDT method and its applications to medical treatment decision rules. There are two ways in which we can use the IDT method. Under the first approach, we operate under the assumption that the decision rule of interest is optimal, and use the prior information that we have to make inferences on the losses. The second approach involves the use of the prior information to derive an optimal region and determine if the losses in this region are reasonable based on our prior information. We illustrate the use of IDT by applying it to the current standard of care (SOC) for the detection and treatment of cervical neoplasias. First, we model the diagnostic and treatment process as a Bayesian sequential decision procedure. Then, we determine the Bayes risk expression for all decision rules and compare the Bayes risk expression for the current SOC decision rule to the Bayes risk expressions of all other decision rules, forming linear inequality constraints on a region under which the current SOC is optimal. The current standard of care has been in use for many years, but we find another decision rule to be optimal. We question whether the current standard of care is the optimal decision rule and will continue to examine these implications and the practicality of implementing this new decision rule. The IDT method provides us with a mathematical technique for dealing with the challenges in formally quantifying patient experiences and outcomes. We believe that it will be applicable to many other disease conditions and become a valuable tool for determining optimal medical treatment standards of care

An Alternative Approach for Estimating the Accuracy of Colposcopy in Detecting Cervical Precancer

Introduction: Since colposcopy helps to detect cervical cancer in its precancerous stages, as new strategies and technologies are developed for the clinical management of cervical neoplasia, precisely determining the accuracy of colposcopy is important for characterizing its continued role. Our objective was to employ a more precise methodology to estimate of the accuracy of colposcopy to better reflect clinical practice. Study design: For each patient, we compared the worst histology result among colposcopically positive sites to the worst histology result among all sites biopsied, thereby more accurately determining the number of patients that would have been underdiagnosed by colposcopy than previously estimated. Materials and Methods: We utilized data from a clinical trial in which 850 diagnostic patients had been enrolled. Seven hundred and ninety-eight of the 850 patients had been examined by colposcopy, and biopsy samples were taken at colposcopically normal and abnormal sites. Our endpoints of interest were the percentages of patients underdiagnosed, and sensitivity and specificity of colposcopy. Results: With the threshold of low-grade squamous intraepithelial lesions for positive colposcopy and histology diagnoses, the sensitivity of colposcopy decreased from our previous assessment of 87.0% to 74.0%, while specificity remained the same. The drop in sensitivity was the result of histologically positive sites that were diagnosed as negative by colposcopy. Thus, 28.4% of the 798 patients in this diagnostic group would have had their condition underdiagnosed by colposcopy in the clinic. Conclusions: In utilizing biopsies at multiple sites of the cervix, we present a more precise methodology for determining the accuracy of colposcopy. The true accuracy of colposcopy is lower than previously estimated. Nevertheless, our results reinforce previous conclusions that colposcopy has an important role in the diagnosis of cervical precancer

Meta-Analysis of Local Invasive Breast Cancer Recurrence After Electron Intraoperative Radiotherapy.

BACKGROUND: Electron intraoperative radiotherapy (IORT) can be used during breast conserving surgery to treat early-stage invasive breast cancer. Using data from current clinical and observational studies, this study aimed to assess the impact of single-fraction electron IORT on local recurrence rates. METHODS: Studies on single-fraction electron IORT during breast conserving surgery were identified through a search of PubMed and Google Scholar, as well as through secondary referencing. Local recurrence rate was the main outcome of interest. A meta-analysis of proportions using a binomial distribution to model the within-study variability and a random effects model was conducted to estimate a pooled local recurrence rate. To estimate a 5-year recurrence rate, a single-sample Poisson-normal model was applied to model the probability of events occurring during a fixed period (60 months). RESULTS: The study identified 13 publications. The analysis demonstrated a pooled monthly local recurrence rate of 0.02% per person-month (95% confidence interval CI 0.00-0.06%) for the studies with a follow-up period shorter than 5 years, 0.03% per person-month (95% CI 0.02-0.06%) for studies with a follow-up period of 5 years or longer, and 0.02% per person-month (95% CI 0.01-0.04%) overall. Based on this model, the predicted 5-year local recurrence rate was 2.7% (range 1.9-3.7%). CONCLUSIONS: According to the published literature, the rate of breast cancer local recurrence after electron IORT was 0.02% per person-month, with an adjusted 5-year recurrence rate of 2.7%. These findings support the recent guidelines from the American Society for Radiation Oncology (ASTRO) supporting the use of electron IORT for low-risk patients

Patient inclusion criteria.

<p>Patient inclusion criteria.</p

Summary of Results: Colposcopy sensitivities, specificities, positive and negative likelihood ratio values.

<p>LG threshold for positive diagnosis by colposcopy was used; LR+ = positive likelihood ratio, LR– = negative likelihood ratio;</p><p>^†Obtained as part of the study.</p><p>Summary of Results: Colposcopy sensitivities, specificities, positive and negative likelihood ratio values.</p