The effect of air pockets in the urinary bladder on the temperature distribution during loco-regional hyperthermia treatment of bladder cancer patients

Mathematical model of MMC chemotherapy for non-invasive bladder cancer treatment

Mitomycin-C (MMC) chemotherapy is a well-established anti-cancer treatment for non-muscle-invasive bladder cancer (NMIBC). However, despite comprehensive biological research, the complete mechanism of action and an ideal regimen of MMC have not been elucidated. In this study, we present a theoretical investigation of NMIBC growth and its treatment by continuous administration of MMC chemotherapy. Using temporal ordinary differential equations (ODEs) to describe cell populations and drug molecules, we formulated the first mathematical model of tumor-immune interactions in the treatment of MMC for NMIBC, based on biological sources. Several hypothetical scenarios for NMIBC under the assumption that tumor size correlates with cell count are presented, depicting the evolution of tumors classified as small, medium, and large. These scenarios align qualitatively with clinical observations of lower recurrence rates for tumor size ≤ 30[mm] with MMC treatment, demonstrating that cure appears up to a theoretical x[mm] tumor size threshold, given specific parameters within a feasible biological range. The unique use of mole units allows to introduce a new method for theoretical pre-treatment assessments by determining MMC drug doses required for a cure. In this way, our approach provides initial steps toward personalized MMC chemotherapy for NMIBC patients, offering the possibility of new insights and potentially holding the key to unlocking some of its mysteries.

A scalable hyperthermic intravesical chemotherapy (HIVEC) setup for rat models of bladder cancer

Hyperthermic intravesical chemotherapy (HIVEC)—whereby the bladder is heated to ± 43 °C during a chemotherapy instillation—can improve outcomes of non-muscle invasive bladder cancer (NMIBC) treatments. Experiments in animal models are required to explore new hyperthermia based treatments. Existing HIVEC devices are not suitable for rodents or large-scale animal trials. We present a HIVEC setup compatible with orthotopic rat models. An externally heated chemotherapeutic solution is circulated in the bladder through a double-lumen catheter with flow rates controlled using a peristaltic pump. Temperature sensors in the inflow channel, bladder and outflow channel allow temperature monitoring and adjustments in real-time. At a constant flow rate of 2.5 mL/min the system rapidly reaches the desired bladder temperature of 42–43 °C with minimal variability throughout a one-hour treatment in a rat bladder phantom, as well as in euthanised and live rats. Mean intraluminal bladder temperatures were 42.92 °C (SD = 0.15 °C), 42.45 °C (SD = 0.37 °C) and 42.52 °C (SD = 0.09 °C) in the bladder phantom, euthanised, and live rats respectively. Thermal camera measurements showed homogenous heat distributions over the bladder wall. The setup provides well-controlled thermal dose and the upscaling needed for performing large scale HIVEC experiments in rats.

Hyperthermia Treatment Planning Including Convective Flow in Cerebrospinal Fluid for Brain Tumour Hyperthermia Treatment Using a Novel Dedicated Paediatric Brain Applicator

Hyperthermia therapy (40-44 °C) is a promising option to increase efficacy of radiotherapy/chemotherapy for brain tumours, in particular paediatric brain tumours. The Chalmers Hyperthermia Helmet is developed for this purpose. Hyperthermia treatment planning is required for treatment optimisation, but current planning systems do not involve a physically correct model of cerebrospinal fluid (CSF). This study investigates the necessity of fluid modelling for treatment planning. We made treatments plans using the Helmet for both pre-operative and post-operative cases, comparing temperature distributions predicted with three CSF models: a convective "fluid" model, a non-convective "solid" CSF model, and CSF models with increased effective thermal conductivity ("high-k"). Treatment plans were evaluated by T90, T50 and T10 target temperatures and treatment-limiting hot spots. Adequate heating is possible with the helmet. In the pre-operative case, treatment plan quality was comparable for all three models. In the post-operative case, the high-k models were more accurate than the solid model. Predictions to within ±1 °C were obtained by a 10-20-fold increased effective thermal conductivity. Accurate modelling of the temperature in CSF requires fluid dynamics, but modelling CSF as a solid with enhanced effective thermal conductivity might be a practical alternative for a convective fluid model for many applications.