Automatic control of finite element models for temperature-controlled radiofrequency ablation

Background  

The finite element method (FEM) has been used to simulate cardiac and hepatic radiofrequency (RF) ablation. The FEM allows modeling of complex geometries that cannot be solved by analytical methods or finite difference models. In both hepatic and cardiac RF ablation a common control mode is temperature-controlled mode. Commercial FEM packages don't support automating temperature control. Most researchers manually control the applied power by trial and error to keep the tip temperature of the electrodes constant.     

Modeling and simulation of novel antenna for the treatment of hepatocellular carcinoma using finite element method

In this article, new interstitial antenna operating at a frequency of 2.45 GHz for the treatment of hepatocellular carcinoma (HCC) using microwave ablation has been investigated. This antenna is basically an asymmetrical miniaturized choke dipole antenna with a pointed needle at the tip. A commercial finite element method (FEM) package, COMSOL Multiphysics 3.4a, has been used to simulate the performance of needle tip choke antenna. The performance of the antenna has been evaluated numerically, taking into account the specific absorption rate, antenna impedance matching and geometry of the obtained thermal lesion, and the temperature distribution plot obtained shows that maximum temperature was attained in this simulation. The antenna is also capable of creating a spherical-shaped ablation zone. The size and shape of the ablation zone can be slightly adjusted by adjusting the choke position in order to maintain spherical ablation zones.     

Patterns and trends in cancer mortality in Colombia 1984–2008

BackgroundCancer has become increasingly acknowledged as a public health issue in Colombia. Rates of the most common malignancies have been generally increasing. We update an evaluation of mortality trends in the major cancers in Colombia one decade ago, discussing the trends in the context of cancer control.MethodsWe calculated the annual age-standardized mortality rates for the major cancer sites by sex between 1984 and 2008; we also present the estimated annual percentage change (EAPC) for the entire period and for the last decade.ResultsThere was an average of 32,000 cancer deaths annually in Colombia in the period studied. Overall cancer mortality rates decreased slightly in both men and women. The four most common sites of cancer death among men were stomach (17.6%), prostate (15.0%), lung (14.8%) and colorectum (6.5%). In women, the most common cancer sites were breast (12.3%), cervix (12.1%), stomach (11.5%) and lung (9.2%). Colorectal and CNS cancers exhibited the greatest increases (EAPC of 2.0% and 3.4% respectively) while the largest declines were seen for cancers of the larynx, stomach and oesophagus (EAPC between ?3% and ?4%). In the last decade, the greatest declines were seen in cervical cancer mortality rates (EAPC = ?3.2).ConclusionsThe slight decrease in mortality trends from all cancers combined is partially driven by the strong declines in mortality of stomach and cervical cancer. It may be still too early to properly evaluate trends in mortality due to other cancers and the relative impact of changing access to health care in Colombia.     

Cancer mortality 1981–2016 and contribution of specific cancers to current socioeconomic inequalities in all cancer mortality: A population-based study

BackgroundIn many high-income countries cancer mortality rates have declined, however, socioeconomic inequalities in cancer mortality have widened over time with those in the most deprived areas bearing the greatest burden. Less is known about the contribution of specific cancers to inequalities in total cancer mortality.MethodsUsing high-quality routinely collected population and mortality records we examine long-term trends in cancer mortality rates in Scotland by age group, sex, and area deprivation. We use the decomposed slope and relative indices of inequality to identify the specific cancers that contribute most to absolute and relative inequalities, respectively, in total cancer mortality.ResultsCancer mortality rates fell by 24 % for males and 10 % for females over the last 35 years; declining across all age groups except females aged 75+ where rates rose by 14 %. Lung cancer remains the most common cause of cancer death. Mortality rates of lung cancer have more than halved for males since 1981, while rates among females have almost doubled over the same period.ConclusionCurrent relative inequalities in total cancer mortality are dominated by inequalities in lung cancer mortality, but with contributions from other cancer sites including liver, and head and neck (males); and breast (females), stomach and cervical (younger females). An understanding of which cancer sites contribute most to inequalities in total cancer mortality is crucial for improving cancer health and care, and for reducing preventable cancer deaths.     

Murine model of hepatic breast cancer

Background and aimsBreast cancer is the most common cancer in women and the second leading cause of cancer-related deaths in this population. Breast cancer related deaths have declined due to screening and adjuvant therapies, yet a driving clinical need exists to better understand the cause of the deadliest aspect of breast cancer, metastatic disease. Breast cancer metastasizes to several distant organs, the liver being the third most common site. To date, very few murine models of hepatic breast cancer exist.MethodsIn this study, a novel murine model of liver breast cancer using the MDA-MB-231 cell line is introduced as an experimental (preclinical) model.ResultsHistological typing revealed consistent hepatic breast cancer tumor foci. Common features of the murine model were vascular invasion, lung metastasis and peritoneal seeding.ConclusionsThe novel murine model of hepatic breast cancer established in this study provides a tool to be used to investigate mechanisms of hepatic metastasis and to test potential therapeutic interventions.     

Profile of cancer in the Eastern Mediterranean region: The need for action

BackgroundMany countries in the Eastern Mediterranean region (EMR) are undergoing marked demographic and socioeconomic transitions that are increasing the cancer burden in region. We sought to examine the national cancer incidence and mortality profiles as a support to regional cancer control planning in the EMR.MethodsGLOBOCAN 2012 data were used to estimate cancer incidence and mortality by country, cancer type, sex and age in 22 EMR countries. We calculated age-standardized incidence and mortality rates (per 100,000) using direct method of standardization.ResultsThe cancer incidence and mortality rates vary considerably between countries in the EMR. Incidence rates were highest in Lebanon (204 and 193 per 100,000 in males and females, respectively). Mortality rates were highest in Lebanon (119) and Egypt (121) among males and in Somalia (117) among females. The profile of common cancers differs substantially by sex. For females, breast cancer is the most common cancer in all 22 countries, followed by cervical cancer, which ranks high only in the lower-income countries in the region. For males, lung, prostate, and colorectal cancer in combination represent almost 30% of the cancer burden in countries that have attained very high levels of human development.ConclusionsThe most common cancers are largely amenable to preventive strategies by primary and/or secondary prevention, hence a need for effective interventions tackling lifestyle risk factors and infections. The high mortality observed from breast and cervical cancer highlights the need to break the stigmas and improve awareness surrounding these cancers.     

Trends in regional cancer mortality in Taiwan 1992–2014

BackgroundAlthough the cancer mortality rate in Taiwan has been declining in recent years, no study has yet reported any regional differences in cancer mortality rates in Taiwan. We hypothesized that regional cancer mortality rates in Taiwan, an ethnically homogeneous society, exhibited no significant variations.MethodsWe investigated the trends in Taiwan regional cancer mortality between 1992 and 2014. We analyzed regional age-standardized cancer mortality rates for lung, liver, colon, stomach, oral, breast, and prostate cancers using the Taiwan Longitudinal Health Insurance Database and Demographic Database. Furthermore, we applied Joinpoint regression analysis to evaluate the trends across different regions.ResultsThere are clear regional variations in mortality rates for liver, stomach, and oral cancers, but not for lung, colon, breast, and prostate cancers. The regional death rates of oral cancer, especially for eastern Taiwan, not only elevate the fastest (APC = 14.78% per year, P < 0.001) but also show the largest disparities between men and women. Regional death rates for stomach cancer, which declined most rapidly, are converging in both general and gender groups. Liver cancer is the only one with regional variations whose trends do not all go in the same direction. We also demonstrated that northern Taiwan has significant regional advantages with respect to cancer mortality.ConclusionsSome but not all cancers in Taiwan show regional disparities. Liver, stomach, and oral cancers in Taiwan exhibit clear regional variations in mortality rates. In particular, the regional variations in oral cancer mortality rates are consistent with those in alcohol consumption.     

Biological significance of piRNA in liver cancer: a review

Abstract

Liver cancer is one of the most common and deadly cancers in the world. In recent years, non-coding RNA has been a hot topic in liver cancer research. piRNAs (PIWI-interacting RNAs) are a new type of small non-coding RNA, which are formed by the PIWI proteins interacting with RNA. The latest research shows that piRNA and PIWI proteins are abnormally expressed in various cancers, including pancreatic, colorectal, breast, etc. piRNA plays an important regulatory role in liver cancer. In this review, we discuss the biological function of piRNAs and new progress in the development of liver cancer, and new targets and ideas for piRNA and PIWI proteins in the diagnosis and treatment of liver cancer.     

Reconfigurable tapered coaxial slot antenna for hepatic microwave ablation

ABSTRACT

Microwave ablation is rapidly being rediscovered and developed for treating many cancers of liver, lung, kidney and bone, as well as arrhythmias and other medical conditions. The microwaves ablate tissue by heating it to cytotoxic temperatures. The microwave antenna design suffers the challenges of effective coupling and penetration into body tissues, uncontrolled power deposition due to applicator construction limitations affecting uniform heating of target region, and narrowband operation leading to mismatch for many patients and detrimental heating. To meet out the requirements of wideband operation and localized lesion reconfigurable linearly tapered slot interstitial wideband antenna has been proposed for working in the 1.38?GHz to 4.31?GHz frequency band. The performance of the antenna is evaluated by using FEM-based HFSS software. The slot height and taper height are reconfigured for parametric analysis achieving maximum impedance matching and spherical ablation zone without requiring any additional adjustable structures. The tapering of the slot in coaxial antenna generates current distribution at the edges of the slot for maximizing specific absorption rate.     

Trends in cancer incidence in the Republic of Mauritius, 1991–2015

IntroductionMauritius, a small state, is among the few African countries where cancer registration is population based and nationwide. We reported trends in cancer incidence for twenty five years as well as the mortality to incidence ratio (MIR) as main quality indicator of the Mauritius National Cancer Registry (MNCR).Materials and methodsWe calculated age standardised incidence rates (ASRs) of cancers by sex and by 5 year age group for five successive year periods from 1991 to 2015. The average annual percentage change (AAPC) were determined by sex and cancer sites. MIRs were compared for the period 2001–2004 and 2012–2015.ResultsIn males, the most common cancer sites (in terms of ASRs per 100,000) were those of the colon-rectum (17.0), prostate (16.5), trachea-bronchus-lung (13.0), stomach (8.4) and lip-oral cavity-pharynx (7.7). The AAPC were +3.9%, +4.2%, +0.5%, -0.1% and -1.3% respectively. In females, the most frequent sites were breast (53.7), colon-rectum (13.2), cervix uteri (11.2), corpus uteri (7.7) and ovary (5.7). The AAPC were +3.4%, +4.4%, -2%, +5.2% and -0.1% respectively. The most significant decrease in MIRs among males were liver (1.9 to 1.0), stomach (1.3 to 0.8) and lung (1.7 to 1.2) cancers while among females, they were pancreas (3.4 to 1.3), liver (1.8 to 1.2) and stomach (1.5 to 0.8) cancers.ConclusionThe most common cancers were those associated with 'westernisation' of lifestyle. Our figures contrast with other Sub-Saharan Africa countries where infection related cancers are most predominant. The MNCR has also improved its data quality over time.     

Finite Element Analysis of Hepatic Radiofrequency Ablation Probes using Temperature-Dependent Electrical Conductivity

Background

Few finite element models (FEM) have been developed to describe the electric field, specific absorption rate (SAR), and the temperature distribution surrounding hepatic radiofrequency ablation probes. To date, a coupled finite element model that accounts for the temperature-dependent electrical conductivity changes has not been developed for ablation type devices. While it is widely acknowledged that accounting for temperature dependent phenomena may affect the outcome of these models, the effect has not been assessed.

Methods

The results of four finite element models are compared: constant electrical conductivity without tissue perfusion, temperature-dependent conductivity without tissue perfusion, constant electrical conductivity with tissue perfusion, and temperature-dependent conductivity with tissue perfusion.

Results

The data demonstrate that significant errors are generated when constant electrical conductivity is assumed in coupled electrical-heat transfer problems that operate at high temperatures. These errors appear to be closely related to the temperature at which the ablation device operates and not to the amount of power applied by the device or the state of tissue perfusion.

Conclusion

Accounting for temperature-dependent phenomena may be critically important in the safe operation of radiofrequency ablation device that operate near 100°C.

     

Association of metformin use with cancer incidence and mortality: A meta-analysis

PurposeTo assess the effect of metformin intake on cancer incidence and mortality.MethodsOriginal articles in English published until June 15, 2012 were searched for in electronic databases (MEDLINE, ISI Web of Science and EMBASE databases) and relevant reviews were examined. Meta-analysis was applied to calculate the summary relative risk (SRR) and their 95% confidence intervals (95% CI). Sensitivity analysis was conducted to assess the robustness of the pooled estimator. The risk of publication bias was assessed by the Egger regression asymmetry test.ResultsAccording to the eligibility criteria, 37 studies comprising 1,535,636 participants, were selected in terms of intervention and data of cancer incidence or mortality. Among metformin users compared with non-users, the SRR for overall-cancer incidence was 0.73 (95% CI, 0.64–0.83) and that for mortality was 0.82 (95% CI, 0.76–0.89). The risk reductions for liver, pancreatic, colorectal and breast cancer incidence were 78%, 46%, 23% and 6%, respectively. Also, metformin can reduce the mortality of liver cancer (SRR, 0.23; 95% CI, 0.09–0.60) and breast cancer (SRR, 0.63; 95% CI, 0.40–0.99). No statistically significant association between metformin and prostate cancer incidence was found.ConclusionsMetformin can reduce the incidence of overall cancer, liver cancer, pancreatic cancer, colorectal cancer and breast cancer as well as the mortality of overall cancer, liver cancer and breast cancer. No beneficial effect on prostate cancer incidence was found for meformin intake in the meta-analysis.     

Geographic disparities of breast cancer incidence in Portugal at the district level: A spatial age-period-cohort analysis, 1998-2011

BackgroundBreast cancer is the most common malignancy in women world-wide and the most common cause of cancer deaths, which can often be managed with early diagnosis and subsequent treatment. Here, we focus on geographic disparities in incidence within Portugal for three age groups of women (30−49; 50−69; 70−84 years).MethodsAge-period-cohort (APC) models are widely used in cancer surveillance, and these models have recently been extended to allow spatially-varying effects. We apply novel spatial APC models to estimate relative risk and age-adjusted temporal trends at the district level for the 20 districts in Portugal. Our model allows us to report on country-wide trends, but also to investigate geographic disparities between districts and trends within districts.ResultsAge-adjusted breast cancer incidence was increasing over 1998–2011 for all three age groups and in every district in Portugal. However, we detect spatially-structured between-district heterogeneity in relative risk and age-adjusted trends (Net Drifts) for each of the three age groups, which is most pronounced in the highly-screened (50−69yo) and late-onset (70−84yo) groups of women.ConclusionsWe present evidence of disparities in breast cancer incidence at a more granular geographic level than previously reported. Some disparities may be due to latent risk factors, which cannot be accounted for by age, birth year, and geographic location alone.ImpactOur study motivates resuming data collection for breast cancer incidence at the district level in Portugal, as well as the study of exogenous risk factors.     

Lifetime Smoking History and Cause-Specific Mortality in a Cohort Study with 43 Years of Follow-Up

BackgroundIn general, smoking increases the risk of mortality. However, it is less clear how the relative risk varies by cause of death. The exact impact of changes in smoking habits throughout life on different mortality risks is less studied.MethodsWe studied the impact of baseline and lifetime smoking habits, and duration of smoking on the risk of all-cause mortality, mortality of cardiovascular diseases (CVD), chronic obstructive pulmonary disease (COPD), any cancer and of the four most common types of cancer (lung, colorectal, prostate, and breast cancer) in a cohort study (Vlagtwedde-Vlaardingen 1965–1990, with a follow-up on mortality status until 2009, n = 8,645). We used Cox regression models adjusted for age, BMI, sex, and place of residence. Since previous studies suggested a potential effect modification of sex, we additionally stratified by sex and tested for interactions. In addition, to determine which cause of death carried the highest risk we performed competing-risk analyses on mortality due to CVD, cancer, COPD and other causes.ResultsCurrent smoking (light, moderate, and heavy cigarette smoking) and lifetime persistent smoking were associated with an increased risk of all-cause, CVD, COPD, any cancer, and lung cancer mortality. Higher numbers of pack years at baseline were associated with an increased risk of all-cause, CVD, COPD, any cancer, lung, colorectal, and prostate cancer mortality. Males who were lifetime persistent pipe/cigar smokers had a higher risk of lung cancer [HR (95% CI) = 7.72 (1.72–34.75)] as well as all-cause and any cancer mortality. A longer duration of smoking was associated with a higher risk of COPD, any and lung cancer [HR (95% CI) = 1.06 (1.00–1.12), 1.03 (1.00–1.06) and 1.10 (1.03–1.17) respectively], but not with other mortality causes. The competing risk analyses showed that ex- and current smokers had a higher risk of cancer, CVD, and COPD mortality compared to all other mortality causes. In addition, heavy smokers had a higher risk for COPD mortality compared to cancer, and CVD mortality.ConclusionOur study indicates that lifetime numbers of cigarettes smoked and the duration of smoking have different impacts for different causes of mortality. Moreover, our findings emphasize the importance of smoking-related competing risks when studying the smoking-related cancer mortality in a general population and that smoking cessation immediately effectively reduces the risk of all-cause and any cancer mortality.     

Increasing incidence and survival of corpus uteri cancer in Estonia over the past two decades

BackgroundCorpus uteri cancer has become the fourth most common female cancer in Europe. In Estonia, the prevalence of obesity is increasing, and corpus uteri cancer survival has been relatively low. The aim of the study was to evaluate incidence, mortality and survival trends of corpus uteri cancer in Estonia by age, stage and histological subtypes with an emphasis on surgical treatment.MethodsEstonian Cancer Registry data on incident cases of corpus uteri cancer were used to examine incidence trends (1995–2016) and calculate relative survival ratios (RSR) (1996–2016). Cases were classified by morphology and FIGO stage. Causes of Death Registry data were used to analyse corrected mortality (1995–2017).ResultsA total of 4281 cases were diagnosed in 1996–2016. A significant increase was seen in age-standardized incidence from 2009, while mortality remained stable throughout the study period. Significant increases were observed for type I cancers and age groups ≥65 years. Overall age-standardized 5-year RSR improved from 70% in 1996–2002 to 78% in 2010–2016. Survival increased for type I cancers, all age groups and all stages (significantly for stage IV). The proportion of surgically treated cases increased significantly from 85% to 89%, with the largest increases seen in older age groups and later stages.DiscussionThe rising corpus uteri cancer incidence in Estonia is driven by the type I cancer trend. Survival gain for later stages and older age groups likely reflected more frequent surgical treatment. To reduce mortality, further efforts are necessary to ensure appropriate care for all patients.     

Routes to diagnosis and the association with the prognosis in patients with cancer – A nationwide register-based cohort study in Denmark

BackgroundThe prognosis of cancer is related to how the cancer is identified, and where in the healthcare system the patient presents, i.e. routes to diagnosis (RtD). We aimed to describe the RtD for patients diagnosed with cancer in Denmark by using routinely collected register-based data and to investigate the association between RtD and prognosis measured as one-year all-cause mortality.MethodsWe conducted a population-based national cohort study by linking routinely collected Danish registry data. We categorised each patient into one of eight specified RtD based on an algorithm using a stepwise logic decision process. We described the proportions of patients with cancer diagnosed by different RtD. We examined associations between RtD and one-year all-cause mortality using logistic regression models adjusting for sex, age, cancer type, year of diagnosis, region of residence, and comorbidity.ResultsWe included 144,635 cancers diagnosed in 139,023 patients in 2014–2017. The most common RtD were cancer patient pathway from primary care (45.9 %), cancer patient pathway from secondary care (20.0 %), unplanned hospital admission (15.8 %), and population-based screening (7.5 %). The one-year mortality ranged from 1.4 % in screened patients to 53.0 % in patients diagnosed through unplanned hospital admission. Patients with an unplanned admission were more likely to die within the first year after diagnosis (OR = 3.38 (95 %CI: 3.24–3.52)) compared to patients diagnosed through the cancer patient pathway from primary care.ConclusionThe majority of cancer patients were diagnosed through a cancer patient pathway. The RtD were associated with the prognosis, and the prognosis was worst in patients diagnosed through unplanned admission. The study suggests that linking routinely collected registry data could enable a national framework for RtD, which could serve to identify variations across patient-, health-, and system-related and healthcare factors. This information could be used in future research investigating markers for monitoring purposes.     

Survival of cancer patients in urban and rural areas of Germany—A comparison

BackgroundCancer care services including cancer prevention activities are predominantly localised in central cities, potentially causing a heterogeneous geographic access to cancer care. The question of an association between residence in either urban or rural areas and cancer survival has been analysed in other parts of the world with inconsistent results. This study aims at a comparison of age-standardised 5-year survival of cancer patients resident in German urban and rural regions using data from 11 population-based cancer registries covering a population of 33 million people.Material and methodsPatients diagnosed with cancers of the most frequent and of some rare sites in 1997–2006 were included in the analyses. Places of residence were assigned to rural and urban areas according to administrative district types of settlement structure. Period analysis and district type specific population life tables were used to calculate overall age-standardised 5-year relative survival estimates for the period 2002–2006. Poisson regression models for excess mortality (relative survival) were used to test for statistical significance.ResultsThe 5-year relative survival estimates varied little among district types for most of the common sites with no consistent trend. Significant differences were found for female breast cancer patients and male malignant melanoma patients resident in city core regions with slightly better survival compared to all other district types, particularly for patients aged 65 years and older.ConclusionWith regard to residence in urban or rural areas, the results of our study indicate that there are no severe differences concerning quality and accessibility of oncological care in Germany among different district types of settlement.     

Radiosynthesis and preclinical evaluation of [18F]FEM as a potential novel PET probe for tumor imaging

In the 21st century, the incidence and mortality of cancer, one of the most challenging diseases in the world, have rapidly increased. The purpose of this study was to develop 2-(2-[¹⁸F]fluoroethoxy)ethyl 4-methylbenzenesulfonate ([¹⁸F]FEM) as a positron emission tomography (PET) agent for tumor imaging. In this study, [¹⁸F]FEM was synthesized with a good radiochemical yield (45.4 ± 5.8%), high specific radioactivity (over 25 GBq/μmol), and commendable radiochemical purity (over 99%). The octanol/water partition coefficient of [¹⁸F]FEM was 1.44 ± 0.04. The probe demonstrated good stability in vitro (phosphate-buffered saline (PBS) and mouse serum (MS)), and binding specificity to five different tumor cell lines (A549, PC-3, HCC827, U87, and MDA-MB-231). PET imaging of tumor-bearing mice showed that [¹⁸F]FEM specifically accumulated at the tumor site of the five different tumor cell lines. The average tumor-to-muscle (T/M) ratio was over 2, and the maximum T/M values reached about 3.5. The biodistribution and dynamic PET imaging showed that most probes were metabolized by the liver, whereas a small part was metabolized by the kidney. Moreover, dynamic brain images and quantitative data showed [¹⁸F]FEM can quickly cross the blood brain barrier (BBB) and quickly fade out, thereby suggesting it may be a promising candidate probe for the imaging of brain tumors. The presented results demonstrated that [¹⁸F]FEM is a promising probe for tumor PET imaging.     

射频消融术对胃癌肝转移患者胃肠功能、DOK3、DOK2水平的影响

摘要 目的：探讨射频消融术对胃癌肝转移患者胃肠功能、酪氨酸激酶下游蛋白（downstream of tyrosinekinase3, DOK3）、酪氨酸激酶下游蛋白（downstream of tyrosinekinase2, DOK2）水平的影响。方法：选取2017年1月-2020年10月我院收治的90例胃癌肝转移患者作为研究对象,随机将其分为两组,对照组45例,给予原发灶和肝转移切除手术治疗;研究组45例,给予肝转移灶射频消融术治疗,观察两组患者的疗效及并发症率,检测治疗后两组患者胃肠功能、DOK3、DOK2水平。结果：研究组的治疗有效率为88.89 %,高于对照组的71.11 %（P＜0.05）;研究组患者腹胀腹痛缓解时间、肠鸣音恢复时间、排气时间、排便时间均短于对照组的相应时间（P＜0.05）;两组患者手术前DOK3、DOK2低表达率对比无明显差异（P＞0.05）,手术后,研究组患者DOK3、DOK2低表达率明显低于对照组,差异具有统计学意义（P＜0.05）;研究组患者的并发症发生率为11.11 %,低于对照组的26.67 %（P＜0.05）;两组患者复发率对比无统计学差异（P＞0.05）。结论：对于胃癌肝转移患者采取射频消融术治疗,其效果明显优于传统手术,可促使胃肠功能恢复,改善DOK3、DOK2的表达水平, 降低并发症风险发生。