Rade Prelevic

Evolutionary assembled neural networks for making medical decisions with minimal regret: Application for predicting advanced bladder cancer outcome

Abstract Development of reliable medical decision support systems has been the subject of many studies among which Artificial Neural Networks (ANNs) gained increasing popularity and gave promising results. However, wider application of ANNs in clinical practice remains limited due to the lack of a standard and intuitive procedure for their configuration and evaluation which is traditionally a slow process depending on human experts. The principal contribution of this study is a novel procedure for obtaining ANN predictive models with high performances. In order to reach those considerations with minimal user effort, optimal configuration of ANN was performed automatically by Genetic Algorithms (GA). The only two user dependent tasks were selecting data (input and output variables) and evaluation of ANN threshold probability with respect to the Regret Theory (RT). The goal of the GA optimization was reaching the best prognostic performances relevant for clinicians: correctness, discrimination and calibration. After optimally configuring ANNs with respect to these criteria, the clinical usefulness was evaluated by the RT Decision Curve Analysis. The method is initially proposed for the prediction of advanced bladder cancer (BC) in patients undergoing radical cystectomy, due to the fact that it is clinically relevant problem with profound influence on health care. Testing on the data of the ten years cohort study, which included 183 evaluable patients, showed that soft max activation functions and good calibration were the most important for obtaining reliable BC predictive models for the given dataset. Extensive analysis and comparison with the solutions commonly used in literature showed that better prognostic performances were achieved while user-dependency was significantly reduced. It is concluded that presented procedure represents a suitable, robust and user-friendly framework with potential to have wide applications and influence in further development of health care decision support systems.

The clinical course of non-muscle invasive bladder cancer after transurethral resection of the tumor with or without subsequent intravesical application of bacillus Calmette-Guérin: The influence of patients gender and age.

UNLABELLED BACGROUND/AIM: The therapy with intravesical instillation of bacillus Calmette-Guérin (BCG) after transurethral resection (TUR) of tumor is the gold standard of treatment of non-muscle invasive bladder cancer (NMIBC). The role and importance of BCG intravesical therapy in various shape of tumors, were confirmed by our previous investigation. The aim of this study was to examine whether incidence of recurrence and tumor regression differs depending on sex and age of patients. METHODS This study included a total of 899 patients suffering from NIMBC, treated at our institution from January 1, 2007 to March 1, 2013. Two groups of patients were formed: patients underwent TUR + BCG therapy (the group I) and the group II with patients in whom TUR was performed as only therapy. These two groups of patients were divided into subgroups of respondents male and female, age 60 years or younger and older than 60 years. Statistical analysis was performed using χ2 test and the Kolmogorov-Smirnov test. RESULTS This research suggests that if the frequency of recurrence is seen as the only parameter, considering all the subjects, the lowest recurrence rate was determined in the male subjects, aged 60 years and younger who had received BCG after TUR. A high statistical significance was found in the incidence of recurrence in patients younger than 60 years, depending on the response to the therapy, while in those older than 60 years, the difference was at the level of statistical significance. This can be attributed to a certain degree of infravesical obstruction in older men. CONCLUSIONS Sex and age of patients may have a significant influence on the course and outcome of NMIBC. The disease has the most malignant and most aggressive behavior when present in males older than 60 years.