Need for Staging Investigations in Newly Diagnosed Breast Cancer: Establishing Local Guidelines for Radiological Staging in Bahrain

Objective

Staging workup and detection of distant metastases is important in newly diagnosed breast cancer in order to make treatment decisions and establish the prognosis. There is wide variation in current recommendations for staging investigations in breast cancer. Routine staging is performed for all patients in Bahrain because of lack of consistent guidelines. Optimization of the criteria for staging is important for identification of metastases, while minimizing harm and costs. The aim of this study was to evaluate factors associated with distant metastases in newly diagnosed patients with breast cancer, in order to establish local guidelines for proper selection of patients for systemic staging.

Materials and Methods

Patients with newly diagnosed breast cancer at Salmaniya Medical Complex in Bahrain who underwent staging investigations between January 2016 and December 2022 were identified from a pathology database. Patients with previous history of cancer, synchronous tumors, bilateral breast cancer and ductal carcinoma in situ were excluded. Clinical, radiological and pathological data were retrospectively analyzed.

Results

A total of 593 patients underwent staging computed tomography and bone scans or a PET scan. Distant metastases were identified in 20.7% of cases. M1 disease was significantly associated with multifocality/multicentricity, high grade tumors, hormone receptor-negative cancers, high Ki67 index, advanced tumor stage, node-positive disease, triple-negative breast cancer, use of PET scans and those who underwent neoadjuvant chemotherapy. Age was not associated with identification of distant metastases.

Conclusion

The prevalence of distant metastases in this population of newly diagnosed patients with breast cancer was higher than previously reported. Routine staging of all patients at presentation was not indicated, especially for asymptomatic patients with early breast cancer. This study identified certain groups of patients with a higher risk of distant metastasis, in whom metastatic workup should be performed. These findings may allow for the development of a local guideline that addresses the question of which breast cancer patients need staging investigations for distant metastases.

Predictors of Unilateral Arm Lymphedema in Non-obese Locoregionally Advanced Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy, Modified Radical Mastectomy, and Postoperative Irradiation

Objective

The most dreaded long-term complication of axillary lymph node dissection remains upper arm lymphedema. Our study has strategized the three most common identified causes of post treatment arm lymphedema, i.e., obesity, radiation, and neoadjuvant chemotherapy and tried to identify the histopathological and clinical or surgical factors which can predict arm lymphedema.

Materials and Methods

This is a prospective observational study was conducted at a tertiary care referral centre in India, with strict inclusion criteria of BMI <30 kg/m2, age <75 years, presence of metastatic axillary node proven by FNAC, received anthracycline based neoadjuvant chemotherapy and postoperative nodal irradiation, and completed 24 months of regular follow-up.

Results

Total of 70 patients were included in the study. The mean age of the patients was 50.3 years (±12.9). lymphovascular invasion, total number of lymph nodes removed from level III, total number of days drain was left in situ and maximum drain output were found to be significantly (p<0.05) associated with arm lymphedema.

Conclusion

In patients undergoing modified radical mastectomy with level III dissection, and postoperative irradiation, the incidence of unilateral arm lymphedema is significantly influenced by several clinicopathological factors like the total number of lymph nodes removed in level III, higher maximal drain output, prolonged duration of drain placement and the presence of lymphovascular invasion.

Impact dynamics of granular debris flows based on a small-scale physical model

The peak pressure of a granular debris flow at low Froude conditions can be calculated with knowledge of the stress anisotropy and the bulk density as well as the run-up height at impact. Based on a small-scale physical model, measurements of stress anisotropy and flow density values at impact are presented and applied to existing run-up prediction models, and further compared with back-calculated run-up coefficients from measured maximum impact pressures. For this purpose, we conducted 17 experiments with impact measurements and six experiments without impact measurements at Froude numbers, ranging from 0.84 to 2.41. Our results indicate that run-up heights are best reproduced by predictive models, either based on energy or mass and moment conservation, when anisotropic stress conditions, found in this study to range from 1.2 to 5.0, and bulk density variations due to impact, ranging in this study from 0.8 to 2.3, are considered. The influence of stress anisotropy and density variation on the run-up prediction differs, depending on the modelling approach. For the calculation of run-up heights based on the energy conservation concept, the influence of stress anisotropy becomes more significant with increasing Froude number, whereas for models based on mass and momentum conservation, bulk density variations have a greater influence on the estimation of the potential run-up.

Management of Landslides in a Rural–Urban Transition Zone Using Machine Learning Algorithms—A Case Study of a National Highway (NH-44), India, in the Rugged Himalayan Terrains

Landslides are critical natural disasters characterized by a downward movement of land masses. As one of the deadliest types of disasters worldwide, they have a high death toll every year and cause a large amount of economic damage. The transition between urban and rural areas is characterized by highways, which, in rugged Himalayan terrain, have to be constructed by cutting into the mountains, thereby destabilizing them and making them prone to landslides. This study was conducted landslide-prone regions of the entire Himalayan belt, i.e., National Highway NH-44 (the Jammu–Srinagar stretch). The main objectives of this study are to understand the causes behind the regular recurrence of the landslides in this region and propose a landslide early warning system (LEWS) based on the most suitable machine learning algorithms among the four selected, i.e., multiple linear regression, adaptive neuro-fuzzy inference system (ANFIS), random forest, and decision tree. It was found that ANFIS and random forest outperformed the other proposed methods with a substantial increase in overall accuracy. The LEWS model was developed using the land system parameters that govern landslide occurrence, such as rainfall, soil moisture, distance to the road and river, slope, land surface temperature (LST), and the built-up area (BUA) near the landslide site. The developed LEWS was validated using various statistical error assessment tools such as the root mean square error (RMSE), mean square error (MSE), confusion matrix, out-of-bag (OOB) error estimation, and area under the receiver operating characteristic (ROC) curve (AUC). The outcomes of this study can help to manage landslide hazards in the Himalayan urban–rural transition zones and serve as a sample study for similar mountainous regions of the world.

Transition Indices of Sediment-Transport Modes on a Debris Flow Resulting from Changing Streambed Gradients

We conducted experiments using an experimental flume with two variable streambed gradients in the upstream and downstream parts with various debris flows, composition sizes, and supply flow rates. We investigated the transition processes of sediment transport modes along the longitudinal distances from the gradient change point using the transition mode indices, ICs¯x, Ih¯x, and IU¯x; these indices were calculated based on measurements of sediment transport concentrations, flow depths, and gravel migration velocities in the debris flow’s front in the downstream part. Using these indices, we postulated that after the debris flow passed the gradient change point, the transition of the sediment transport modes progressed by changing the measured parameters to those in the steady-state condition on the gradient of the downstream parts. In addition, these indices suggested that the gravel migration velocities in the flow front interior changed most rapidly after passing the gradient change point, and that flow depths tended to change most slowly. Finally, the indices suggested that as the debris flow material became finer and the supplied flow rates became larger, the longitudinal transition sections tended to be longer because the momentum needed to transport the material was less than the total debris flow momentum.

A Quasi-Single-Phase Model for Debris Flows Incorporating Non-Newtonian Fluid Behavior

Debris-flow modeling is a great challenge due to its complex physical mechanism that remains poorly understood. The present research incorporates the effect of rheological features of the non-Newtonian fluid into the complete quasi-single-phase mixture model, which explicitly accommodates the interactions between flow, non-uniform sediment transport, and bed evolution. The effect of rheological features is estimated by Hersch–Bulkley–Papanastasiou model that can be simplified to Bingham or Newtonian models with specific coefficients. The governing equations are solved by a fully conservative numerical algorithm, using an explicit finite volume discretization with well-balanced slope-limited centered scheme combined with an implicit discretization method. One set of large-scaled U.S. Geological Survey debris-flow experiments is applied to investigate the influence of the non-Newtonian fluid on debris-flow modeling. It is found that the present model closed by Hersch–Bulkley–Papanastasiou model performs better than the models without considering effect of rheological features, which may facilitate the development of quasi-single-phase mixture modeling for debris flows.

Some Considerations for Using Numerical Methods to Simulate Possible Debris Flows: The Case of the 2013 and 2020 Wayao Debris Flows (Sichuan, China)

Using a numerical simulation method based on physical equations to obtain the debris flow risk range is important for local-scale debris flow risk assessment. While many debris flow models have been used to reproduce processes after debris flow occurrence, their predictability in potentially catastrophic debris flow scenarios has mostly not been evaluated in detail. Two single-phase flow models and two two-phase models were used to reproduce the Wayao debris flow event in 2013. Then the Wayao debris flow event in 2020 was predicted by the four models with the same parameters in 2013. The depth distributions of the debris source and deposition fan were mapped by visual interpretation, electric resistivity surveys, field measurements, and unmanned aerial vehicle (UAV) surveys. The digital elevation model (DEM), rainfall data, and other simulation parameters were collected. These models can reproduce the geometry and thickness distribution of the debris flow fan in 2013. However, the predictions of the runout range and the deposition depth are quite different from the actuality in 2020. The performance and usability of these models are compared and discussed. This could provide a reference for selecting physical models to assess debris-flow risk.

Laboratory Analysis of Debris Flow Characteristics and Berm Performance

In this study, laboratory tests were used to determine the deposition characteristics (runout distance, lateral width, and deposition area) of debris flow and their relationships with the flow characteristics (flow velocity and flow depth) according to the presence of a berm. An experimental flume 1.3 to 1.9 m long, 0.15 m wide, and 0.3 m high was employed to investigate the effects of channel slope and volumetric concentration of sediment with and without the berm. The runout distance (0.201–1.423 m), lateral width (0.045–0.519 m), and deposition area (0.008–0.519 m2) increased as the channel slope increased and as the volumetric concentration of sediment decreased. These quantities also increased with the flow velocity and flow depth. In addition, the maximum reductions in the runout distance, lateral width, and deposition area were 69.1%, 65.9%, and 93%, respectively, upon berm installation. The results of this study illustrate general debris flow characteristics according to berm installation; the reported relationship magnitudes are specific to the experimental conditions described herein. However, the results of this study contribute to the design of site-specific berms in the future by providing data describing the utility and function of berms in mitigating debris flow.

A brief review of (multi-scale) modelling approaches to segregation

Segregation in dense granular flows is a large problem in many areas of industry and the natural environment. In the last few years an advection-diffusion style framework has been shown to capture segregation in many geometries. Here, we review the different ways such a framework has been obtained by different authors, compare the forms and make recommendations for the best form to use. Finally, we briefly outline some of the remaining open-questions.

Initiation and Flow Conditions of Contemporary Flows in Martian Gullies

Understanding the initial and flow conditions of contemporary flows in Martian gullies, generally believed to be triggered and fluidized by CO2 sublimation, is crucial for deciphering climate conditions needed to trigger and sustain them. We employ the RAMMS (RApid Mass Movement Simulation) debris flow and avalanche model to back calculate initial and flow conditions of recent flows in three gullies in Hale crater. We infer minimum release depths of 1.0-1.5 m and initial release volumes of 100-200 m3. Entrainment leads to final flow volumes that are ∼2.5-5.5 times larger than initially released, and entrainment is found necessary to match the observed flow deposits. Simulated mean cross-channel flow velocities decrease from 3-4 m/s to ∼1 m/s from release area to flow terminus, while flow depths generally decrease from 0.5-1 to 0.1-0.2 m. The mean cross-channel erosion depth and deposition thicknesses are ∼0.1-0.3 m. Back-calculated dry-Coulomb friction ranges from 0.1 to 0.25 and viscous-turbulent friction between 100 and 200 m/s2, which are values similar to those of granular debris flows on Earth. These results suggest that recent flows in gullies are fluidized to a similar degree as are granular debris flows on Earth. Using a novel model for mass flow fluidization by CO2 sublimation we are able to show that under Martian atmospheric conditions very small volumetric fractions of CO2 of ≪1% within mass flows may indeed yield sufficiently large gas fluxes to cause fluidization and enhance flow mobility.

An analysis of the entrainment effect of dry debris avalanches on loose bed materials

Substrate entrainment can greatly influence the mass movement process of a debris avalanche because it can enlarge the landslide volume and change the motion characteristics of the sliding masses. To study the interaction between debris avalanches and erodible substrate, physical modeling experiments varying in the mass of granular flow and substrate thickness were performed. The experimental results show that both the entrained materials and the maximum erosion depth are increased with increasing mass of the debris avalanche and decreasing substrate thickness. During the experiment, several tests were recorded using a high-speed digital camera with a frequency of 500 frames per second, so that the process of entrainment could be clearly observed. Combined with the experiment result and results of previous studies from predecessors, the entrainment mechanism during debris avalanches are analyzed and discussed. The entrainment effect of the sliding masses on the loose bed materials include basal abrasion and impact erosion of the avalanche front, the latter of which can contribute to the former by failing or yielding the erodible bed.

A depth-averaged debris-flow model that includes the effects of evolving dilatancy. I. Physical basis

To simulate debris-flow behaviour from initiation to deposition, we derive a depth-averaged, two-phase model that combines concepts of critical-state soil mechanics, grain-flow mechanics and fluid mechanics. The model's balance equations describe coupled evolution of the solid volume fraction, m , basal pore-fluid pressure, flow thickness and two components of flow velocity. Basal friction is evaluated using a generalized Coulomb rule, and fluid motion is evaluated in a frame of reference that translates with the velocity of the granular phase, v s . Source terms in each of the depth-averaged balance equations account for the influence of the granular dilation rate, defined as the depth integral of ∇⋅ v s . Calculation of the dilation rate involves the effects of an elastic compressibility and an inelastic dilatancy angle proportional to m − m eq , where m eq is the value of m in equilibrium with the ambient stress state and flow rate. Normalization of the model equations shows that predicted debris-flow behaviour depends principally on the initial value of m − m eq and on the ratio of two fundamental timescales. One of these timescales governs downslope debris-flow motion, and the other governs pore-pressure relaxation that modifies Coulomb friction and regulates evolution of m . A companion paper presents a suite of model predictions and tests.

A depth-averaged debris-flow model that includes the effects of evolving dilatancy. II. Numerical predictions and experimental tests

We evaluate a new depth-averaged mathematical model that is designed to simulate all stages of debris-flow motion, from initiation to deposition. A companion paper shows how the model's five governing equations describe simultaneous evolution of flow thickness, solid volume fraction, basal pore-fluid pressure and two components of flow momentum. Each equation contains a source term that represents the influence of state-dependent granular dilatancy. Here, we recapitulate the equations and analyse their eigenstructure to show that they form a hyperbolic system with desirable stability properties. To solve the equations, we use a shock-capturing numerical scheme with adaptive mesh refinement, implemented in an open-source software package we call D-Claw. As tests of D-Claw, we compare model output with results from two sets of large-scale debris-flow experiments. One set focuses on flow initiation from landslides triggered by rising pore-water pressures, and the other focuses on downstream flow dynamics, runout and deposition. D-Claw performs well in predicting evolution of flow speeds, thicknesses and basal pore-fluid pressures measured in each type of experiment. Computational results illustrate the critical role of dilatancy in linking coevolution of the solid volume fraction and pore-fluid pressure, which mediates basal Coulomb friction and thereby regulates debris-flow dynamics.

Collapse of granular-liquid mixtures over rigid, inclined beds

This work deals with the propagation of granular-liquid waves over rigid beds, originated by the sudden removal of a sluice gate in a rectangular, inclined flume. In particular, we experimentally investigate the role of the initial volume ratio of granular material-monodispersed plastic cylinders-to water, the flume width, and the bed roughness on the time evolution of the granular front. Due to the presence of the interstitial liquid, we observed previously unreported types of collapse: (i) discontinuous flows, where the granular material stops after an initial spreading, and then flows again when the liquid, initially slower than the particles, reaches the front and remobilizes it; (ii) flows evolving into uniformly progressive waves at an angle of inclination of the flume well below the angle of repose of the dry granular material. We also noticed an unusual influence of the lateral confinement on the wave propagation. Indeed, the constant front velocity in the uniformly progressive state decreases when the channel width increases. We claim that the latter observation and the presence of discontinuous flows, strongly support the idea that only two-phase, stratified mathematical models can predict the behavior of unsteady, granular-liquid mixtures at high concentration, such as debris flows.