Comparing Effects of Treatment: Controlling for Confounding

BACKGROUND

Determining true causal links between an intervention and an outcome forms an imperative task in research studies in neurosurgery. Although the study results sometimes demonstrate clear statistical associations, it is important to ensure that this represents a true causal link. A confounding variable, or confounder, affects the association between a potential predictor and an outcome.

OBJECTIVE

To discuss what confounding is and the means by which it can be eliminated or controlled.

METHODS

We identified neurosurgical research studies demonstrating the principles of eliminating confounding by means of study design and data analysis.

RESULTS

In this report, we outline the role of confounding in neurosurgical studies after giving an overview of its identification. We report on the definition of confounding and effect modification, and the differences in the 2. We explain study design techniques to eliminate confounding, including simple, block, stratified, and minimization randomization, along with restriction of sample and matching. Data analysis techniques of eliminating confounding include regression analysis, propensity scoring, and subgroup analysis.

CONCLUSION

Understanding confounding is important for conducting a good research study. Study design techniques provide the best way to control for confounders, but when not possible to alter study design, data analysis techniques can also provide an effective control.

The state of cancer in Meru, Kenya: a retrospective study

Background: It is projected that by 2030, 70% of all cancer related deaths will occur in low-middle income countries. However, data on the state of cancer in most African countries is scanty. Cancer estimates for Kenya are based on the Nairobi and Eldoret cancer registries, leaving most parts of the country unrepresented. Lacking national coverage, these data do not accurately reflect Kenya’s cancer burden. The paucity of reliable data impedes formulation of effective cancer control strategies and cancer research prioritization. Here, we report the findings of a retrospective study of the cancer state in Meru County, Kenya. Methods: A retrospective analysis of patient files at Meru hospice was carried out. 2349 cancer cases seen at the Meru hospice between 2003 and 2018 were analyzed. Data abstracted from the records included patient age, gender and cancer type. The abstracted data was analyzed by descriptive statistics. Results: Our results indicate that cancer is almost evenly distributed across genders, with men accounting for 49% and women 51%. Stomach cancer rates are strikingly elevated and equal to those in countries with the highest stomach cancer rates globally – making it the commonest cancer in this region (14%). Among men, the most common cancers affect the prostate (18%), stomach (17%), esophagus (14%), head & neck (12%), liver (8%) and colorectum (5%). Among women, the commonest are cancers of the breast (22%), cervix (20%), stomach (11%), esophagus (8%), head & neck (6%) and liver (5%). Breast cancer occurs at a notably early age, with 20% of those affected aged below 40. Lung cancer rates are notably low in this region (1.3%) relative to world estimates. Conclusion: Cancer distribution in Meru is nearly even between sexes. Our analysis suggests that the Meru region is a stomach cancer hotspot and that it also experiences elevated esophageal cancer levels.

Plasma Cell-Free DNA Testing of Patients With EGFR Mutant Non–Small-Cell Lung Cancer: Droplet Digital PCR Versus Next-Generation Sequencing Compared With Tissue-Based Results

PURPOSE

To compare the results of plasma cell-free DNA (cfDNA) droplet digital PCR (ddPCR) and next-generation sequencing (NGS) on detection of epidermal growth factor receptor ( EGFR) primary activating mutations and p.T790M with results of tissue analysis in patients with EGFR mutated non–small-cell lung cancer.

METHODS

All patients with EGFR mutated non–small cell lung cancer for which a pathology and a plasma specimen were available upon progression between November 2016 and July 2018 were selected. Concordance, Cohen’s κ, and intraclass correlation coefficients were calculated.

RESULTS

Plasma cfDNA and pathology specimens of 36 patients were analyzed. Agreement between ddPCR and NGS was 86% (κ = 0.63) for the primary activating mutation and 94% (κ = 0.89) for the p.T790M detection. Allele ratios were comparable, with an intraclass correlation coefficient of 0.992 and 0.997, respectively. Discrepancies of some degree were found in 15 patients (41.7%). In six patients (16.7%), no mutations were detected in cfDNA. In three patients (8.3%), p.T790M was detected in plasma but not in the pathology specimen, whereas in three other patients (8.3%), p.T790M was demonstrated in the pathology specimen but not in plasma. Concordance of cfDNA and pathology for the primary activating mutation was 69% for ddPCR and 83% for NGS. For the detection of p.T790M, this was 75% (κ = 0.49) for ddPCR as well as for NGS.

CONCLUSION

Mutual agreement is high between NGS and ddPCR in cfDNA on the level of a specific mutation, with comparable ratio results. Plasma testing of EGFR primary activating mutations and p.T790M shows high concordance with pathology results, for NGS as well as for ddPCR, depending on the extent of the panel used. In NGS, more genetic aberrations can be investigated at once.

Fucoidan suppresses the gastric cancer cell malignant phenotype and production of TGF-β1 via CLEC-2

The sulfated polysaccharide fucoidan displays excellent anticancer properties with low toxicity in many kinds of cancers. However, its detailed pharmacological effect and mechanism of action in gastric carcinoma remains unclear. In this study, we found that fucoidan could suppress gastric cancer (GC) cell growth, as well as cell migration and invasion. A cytokine expression screen demonstrated that transforming growth factor beta 1 (TGF-β1) secretion was decreased in fucoidan-treated cells. Fucoidan has been reported to be a platelet agonist for the C-type lectin-like receptor 2 (CLEC-2), and our previous research found that upregulation of CLEC-2 inhibited GC progression. Here, we confirmed that fucoidan, combined with CLEC-2, significantly increased CLEC-2 expression in GC cells via the transcription factor caudal type homeobox transcription factor 2, an important regulator of gut homeostasis. In addition, the inhibitory effect of fucoidan on the GC cell malignant phenotype and TGF-β1 secretion could be restored by knocking down CLEC-2. Thus, our data suggest that fucoidan targets CLEC-2 to exert antitumorigenesis and antimetastatic activity, suggesting that fucoidan is a promising treatment for gastric carcinoma.

Glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) variants and breast cancer risk in Burkina Faso

Background and objective

Breast cancer remains the most common cause of cancer mortality in women. The aim of this study was to investigate associations between genetic variability in GSTM1 and GSTT1 and susceptibility to breast cancer.

Methods

Genomic DNA was extracted from blood samples for 80 cases of histologically diagnosed breast cancer and 100 control subjects. Genotyping analyses were performed by PCR-based methods. Associations between specific genotypes and the development of breast cancer were examined using logistic regression to calculate odds ratios [1] and 95% confidence intervals (95%CI).

Results

No correlation was found between GSTM1-null and breast cancer (OR = 1.83; 95%CI 0.90-3.71; p = 0.10), while GSTT1-null (OR = 2.42; 95%CI 1.17-5.02; p= 0.01) was associated with increased breast cancer risk. The GSTM1/GSTT1 double null was not associated with an increased risk of developing breast cancer (OR = 2.52; 95%CI 0.75-8.45; p = 0.20). Furthermore, analysis found no association between GSTM1-null (OR =1.12; 95%CI 0.08-15.50; p = 1.00) or GSTT1-null (OR = 1.71; 95%CI 0.13-22.51; p = 1.00) and the disease stage of familial breast cancer patients or sporadic breast cancer patients (GSTM1 (OR = 0.40; 95%CI 0.12-1.32; p = 0.20) and GSTT1 (OR = 1.41; 95%CI 0.39-5.12; p = 0.75)). Also, body mass index (BMI) was not associated with increased or decreased breast cancer risk in either GSTM1-null (OR = 0.60; 95%CI 0.21-1.68; p = 0.44) or GSTT1-null (OR = 0.60; 95%CI 0.21-1.68; p =0.45).

Conclusion

Our results suggest that only GSTT1-null is associated with increased susceptibility to breast cancer development.

Tobacco, air pollution, environmental carcinogenesis, and thoughts on conquering strategies of lung cancer

Each year there will be an estimated 2.1 million new lung cancer cases and 1.8 million lung cancer deaths worldwide. Tobacco smoke is the No.1 risk factors of lung cancer, accounting for > 85% lung cancer deaths. Air pollution, or haze, comprises ambient air pollution and household air pollution, which are reported to cause 252,000 and 304,000 lung cancer deaths each year, respectively. Tobacco smoke and haze (hereafter, smohaze) contain fine particles originated from insufficient combustion of biomass or coal, have quite similar carcinogens, and cause similar diseases. Smohaze exert hazardous effects on exposed populations, including induction of a large amount of mutations in the genome, alternative splicing of mRNAs, abnormalities in epigenomics, initiation of tumor-promoting chronic inflammation, and facilitating immune escape of transformed cells. Tackling smohaze and development of multi-targets-based preventive and therapeutic approaches targeting smohaze-induced carcinogenesis are the key to conquer lung cancer in the future.

3-{[(2,3-Dichlorophenyl)amino]methyl}-5-(furan-2-ylmethylidene)-1,3-thiazolidine-2,4-dione

The compound 3-{[(2,3-Dichlorophenyl)amino]methyl}-5-(furan-2-ylmethylidene)-1,3-thiazolidine-2,4-dione has been designed, synthesized, and screened for its in vitro antibreast cancer activity, using human breast adenocarcinoma cell lines (MCF-7) and in vitro anti-inflammatory activity. By hemolysis assay, it showed that it has a nonhemolytic and nontoxic effect on human blood cell. The title compound 5, subjected to in vitro activities, showed that it is cytotoxic with an IC50 of 42.30 µM and a good anti-inflammatory agent. The docking results against cyclin dependent kinase 2 (CDK2) (PDB ID: 3QQK) gave insights on its inhibitory activity.

Evaluation of Anti-cancer and Pro-apoptotic Activities of Iranian Green Tea Extract Against A549,PC3, and MCF-7 Cancer Cell Lines

Introduction: Green tea contains active polyphenols including catechins. The goal of the current study was to evaluate anti-cancer effects of Iranian green tea extract (IGTE) on 3 human cancer cell lines including A549, PC3, and MCF-7. Methods: First, Camellia sinensis was obtained from Lahijan, a city in the north of Iran and then IGTE was prepared. Next, catechins of IGTE were determined using high-performance liquid chromatography (HPLC). Finally, the cell viability of different cancer cells was evaluated by treatment with IGTE at concentration between 100 and 1000 µg/mL for 72 hours using MTT assay. Cell death of treated cancer cells was assessed by DAPI staining and RT-PCR method. Results: Our results demonstrated the potential anti-tumor activity of IGTE on MCF-7 cells (IC50= 400 µM), A549 cells (IC50= 500 µM), and PC3 cells (IC50= 600 µM), respectively. Chromatin damages within the nucleus of the treated cancer cells were shown. In addition, we found that IGTE induced apoptosis by up-regulation of Bax (a pro-apoptotic protein) and down-regulation of Bcl2 (an anti-apoptotic protein). Conclusion: Herein, we showed that IGTE is a potent natural product with anti-tumor activity on breast, lung, and prostate cancer cells. The efficacy of current therapies against cancer is limited by a range of adverse effects, toxicity, and drug resistance; therefore, new therapeutic strategies and more effective agents, particularly with natural origin, are desired and green tea may be a potent candidate in the field of cancer therapy

An omnibus approach to assess covariate balance in observational studies using the distance covariance

Adequate baseline covariate balance among groups is critical in observational studies designed to estimate causal effects. Propensity score-based methods are popular ways to achieve covariate balance among groups. Existing methods are not easily generalizable to situations in which covariates of mixed type are collected nor do they provide a convenient way to compare the overall covariate vector distributions. Instead, covariate balance is assessed at the individual covariate level, thus the potential for increased overall type I error. We propose the use of the distance covariance, developed by Székely and colleagues, as an omnibus test of independence between covariate vectors and study group. We illustrate the advantages of this methodology in simulated data and in a cardiac surgery study designed to assess the impact of preoperative statin therapy on outcomes.

Nationwide Outcomes after Renal Transplantation from Kidney-Only versus Multiple-Organ Deceased Donors

To assess renal transplant outcomes after donation by kidney-only (KO) versus multiple-organ (MO) donors on a national scale. The United Network for Organ Sharing database was examined for patients undergoing isolated kidney transplant from a deceased donor from 2000 through 2016. Comparison was made between recipients of grafts from KO versus MO donors at baseline and in a cohort of KO and MO recipients matched via propensity scoring. Outcomes of interest included delayed graft function (DGF), patient survival, and the cumulative incidence of graft loss. There were 33,326 recipients in the KO cohort versus 144,690 in the MO cohort. Donation after cardiac death donors were more prevalent in the KO group (43.8% vs 5.3%; P < 0.001). DGF occurred in 36.1 per cent of the KO versus 22.7 per cent of the MO recipients ( P < 0.001). Five-year survival was 79.5 per cent versus 83.4 per cent ( P < 0.001) in the KO versus MO group. After propensity matching, DGF was still more common in the KO group (33.1% vs 30.1%; P < 0.001). Patient survival was similar (79.5% KO vs 80.1% MO; P = 0.117). Cumulative incidence of graft loss was higher in the KO group (17.8% vs 16.8%). Survival outcomes from KO donors are actually quite good and should not be considered as inferior to MO donors.

Long-term survival between total colectomy versus proctocolectomy in patients with FAP: a registry-based, observational cohort study

Background:

The best surgical choice for patients with familial adenomatous polyposis (FAP) is still debated. No prospective trials have been carried out to evaluate the pros and cons of the recommended procedures: total colectomy (ileorectal anastomosis [IRA]) vs restorative proctocolectomy (ileal pouch–anal anastomosis [IPAA]). The aim of this study was to provide a basis for tailored precision surgery in patients with FAP.

Methods:

We conducted a retrospective review of patients with FAP who underwent surgery and were registered in a dedicated database in Milan, Italy. Twenty-year survival related to surgical approach and prognostic factors were investigated using a Cox regression model.

Results:

A total of 925 patients underwent surgery between 1947 and 2015: 340 (36.8%) IPAA and 585 (63.2%) IRA. Colorectal cancer (CRC) at surgery was diagnosed in 28.6% of patients and a pathogenic APC variant was identified in 88%. During a median follow-up of 129 months, 150 patients died. The survival probability was significantly higher in the IRA than the IPAA group: 0.82 vs 0.75 (hazard ratio [HR] 0.6, 95% confidence interval [CI] 0.42–0.84). Multivariable regression modeling adjusted for propensity scores showed a similar difference, although no longer significant. Multivariable analysis indicated as independent risk factors CRC (HR 4.68, 95% CI 3.04–7.20) and age at surgery (HR 1.03, 95% CI 1.02–1.06). Among patients without cancer, the main risk factor for shorter survival was older age (HR 1.06, 95% CI 1.04–1.09).

Conclusion:

The study confirms excellent long-term results of surgical approaches with IRA and IPAA, suggesting that the best surgical choice may be an individually and clinically tailored approach, preferably at a young age.

Pembrolizumab and Nivolumab in the treatment of Non-small cell lung cancer (NSCLC)

Lung cancer is a disease difficult to treat and with low survival rates, especially non-smaller cell lung cancer (NSCLC). To treat cancer in advanced stages, new methods had arisen like immunotherapy. Pembrolizumab and nivolumab are IgG4 antibodies targeting programmed death cell receptor (PD-1) used for cancer immunotherapy, that blocks the protection that has cancer cells against the immune system. This antibody works binding and blocking the PD-1 membrane protein of T cells, which is responsible for cell recognition. If T cells cannot recognize the cells, then it would attack, so in this way, the immune system can be enhanced. Pembrolizumab and nivolumab have a variable region that is capable of recognizing the PD-1 receptor, and this plays an important role to kill cancer cells. The structure of the complex PD -1 and its ligand PD-L1 or PD-L2 reveals the structural basis of the PD-1. The interaction with a human antibody has been studied with antibody fragments revealing the molecular basis for the blockade of PD1 / PDL1-PDL2 interaction by pembrolizumab and nivolumab. Different studies involving immunotherapy have shown the remarkable results of pembrolizumab and nivolumab over current chemotherapy for cancer treatment making available a possible way for a new treatment for lung cancer. In a comparative analysis made between those immune checkpoint inhibitors had found the efficacy of pembrolizumab for treatment of NSCLC.

Prostate-specific antigen response patterns during cabazitaxel therapy in patients with metastatic castration-resistant prostate cancer

Background

The objective of this study was to categorize prostate-specific antigen (PSA) response during cabazitaxel therapy in patients with metastatic castration-resistant prostate cancer (mCRPC) into different patterns and to investigate the prognostic impact of the PSA response patterns.

Methods

We reviewed data from patients with mCRPC who had been treated with cabazitaxel therapy at four institutions belonging to Tokai Urologic Oncology Research Seminar. Patients eligible for this study had received at least three cycles of cabazitaxel treatment at three- or four-week intervals. The PSA response patterns were categorized as primary resistance (PR), response (RE), stabilization (ST), and fluctuating (FL). The overall survival (OS) was compared among the patterns.

Results

Data from a total of 50 patients were analyzed in this study. The number of patients exhibiting PR, RE, ST and FL patterns were 18 (36%), 14 (28%), 12 (24%) and 6 (12%), respectively. The median (95% CI) OS of patients with PR and RE patterns was 10.7 (5.6–15.9) and 14.9 (6.8–23.0) months, respectively, and was not reached for patients with ST and FL patterns. The OS of patients with the FL pattern was significantly better than that of patients with PR (P = 0.012) and RE (P = 0.010) patterns.

Conclusion

There were some patients whose PSA were fluctuating during cabazitaxel therapy in patients with mCRPC. Because the prognosis of such patients was relatively good, the judgment to discontinue the cabazitaxel therapy after PSA rise followed by decrease should be made prudently.

Unmet dental care needs in South Korea: how do they differ by insurance system?

Objectives

This study aimed to analyse and compare the influence of National Health Insurance and Medical Aid coverage on the persistency of unmet dental care needs in South Korea.

Methods

This study was based on a longitudinal sample of 4461 adults aged 19 years and older who participated in the South Korea Health Panel from 2011 to 2014, using weights to make the data nationally representative. Propensity score matching was used to adjust the demographic, socioeconomic and health status information of National Health Insurance and Medical Aid groups. Panel logistic regression analyses were conducted to examine the association between health insurance type and unmet dental needs for three consecutive years.

Results

The odds of the lowest income group reporting unmet dental care needs compared with the highest income group was 6.75 (confidence interval 5.94−7.67), which reduced to 4.19 (confidence interval 3.76−4.67) in the models including health insurance schemes. Additionally, Medical Aid recipients (odds ratio 2.49; 95% confidence interval 2.18−2.48) were more likely to have unmet needs than those covered by National Health Insurance.

Conclusions

The dental care needs of Medical Aid beneficiaries were not being met, unlike those of the National Health Insurance beneficiaries. Such evidence suggests that increasing health insurance coverage to include several essential dental services would improve the accessibility of dental care services for Medical Aid beneficiaries.

Mucin 16 and kallikrein 13 as potential prognostic factors in colon cancer: Results of an oncological 92-multiplex immunoassay

Colon cancer represents one of the most common cancers in the world. Despite improved treatment, mortality remains high. In order to improve the assessment of prognosis for colon cancer patients, identifying new prognostic markers remains necessary. We analyzed preoperative serum samples from 148 colon cancer patients surgically treated at Helsinki University Hospital from 1998 through 2002 using a multiplex proximity extension assay (Oncology II panel, Olink Bioscience, Uppsala, Sweden), a panel constituting 92 immunological and oncological markers. We performed univariate and multivariate analyses on these patients and calculated the disease-specific survival among patients using the log-rank test for Kaplan–Meier estimates. In the univariate survival analysis of 92 biomarkers, 26 resulted in p < 0.1. Among these, eight biomarkers emerged as statistically significant (p < 0.05). Patients with low levels of kallikrein 13 had a poor prognosis. Moreover, patients with high levels of amphiregulin, carcinoembryonic antigen-related adhesion molecule 5, interleukin 6, mucin 16, syndecan 1, transforming growth factor alpha, and vimentin also had a poor prognosis. In the multivariate analysis, kallikrein 13 and mucin 16 emerged as independent prognostic markers. The role of kallikrein 13, a member of the serine protease kallikrein biomarker family, in tumorigenesis remains unclear. Mucin 16 is also known as carbohydrate antigen 125, a well-known ovarian cancer biomarker. Patients with low levels of kallikrein 13 (hazard ratio: 0.36; 95% confidence interval: 0.14–0.92; p = 0.033) and high levels of mucin 16 (hazard ratio: 3.15; 95% confidence interval: 1.68–5.93; p < 0.005) had a poor prognosis. Mucin 16 and kallikrein 13 represent independent prognostic markers for colon cancer. Furthermore, the clinical utility of mucin 16 and kallikrein 13 serum tests warrants additional investigation.

Cancer modeling meets human organoid technology

Organoids are microscopic self-organizing, three-dimensional structures that are grown from stem cells in vitro. They recapitulate many structural and functional aspects of their in vivo counterpart organs. This versatile technology has led to the development of many novel human cancer models. It is now possible to create indefinitely expanding organoids starting from tumor tissue of individuals suffering from a range of carcinomas. Alternatively, CRISPR-based gene modification allows the engineering of organoid models of cancer through the introduction of any combination of cancer gene alterations to normal organoids. When combined with immune cells and fibroblasts, tumor organoids become models for the cancer microenvironment enabling immune-oncology applications. Emerging evidence indicates that organoids can be used to accurately predict drug responses in a personalized treatment setting. Here, we review the current state and future prospects of the rapidly evolving tumor organoid field.

Ways to use interventions to increase participation in mail-out bowel cancer screening: a systematic review and meta-analysis

The impact of colorectal cancer can be reduced through nationwide fecal occult blood test (FOBT) screening. Unfortunately, participation in screening programs are low with interventions only increasing participation modestly.

This meta-analysis explores if intervention effectiveness can be increased by targeting specific subpopulations with specific interventions or by combining interventions. Six databases were searched for studies aiming to increase participation in mail-out FOBT screening. To investigate if interventions are more effective for certain subpopulations, the difference in (log) Risk Ratios (RRs) between alternate subpopulations (male vs. female; low vs. high Socioeconomic Status (SES); &lt;65 vs. ≥65 years) was assessed. To investigate if interventions should be combined, uptake rates for single interventions were compared to uptake rates for combined interventions. Cochrane Collaboration tools were used to assess the risk of bias.

Searches found 3,436 articles, with 32 meeting the inclusion criteria. These contained 30 trials that reported uptake rates within subpopulations and 17 trials that combined interventions. Most differences in intervention effects between subpopulations were nonsignificant. Combining interventions led to greater participation, RR = 1.06, confidence interval [1.03; 1.10]. As interventions rarely affect subpopulations differently, targeting them at specific subpopulations may be an ineffective strategy. While individual interventions show modest effects, these results indicate that future programs might overcome this by combining interventions together. Care is needed when selecting interventions to combine as adding some interventions (e.g., additional print materials) can reduce the effectiveness of a combined strategy. Future research should examine methods for effectively combining interventions in nationwide programs to maximize participation.

The potential therapeutic actions of melatonin in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and lethal disease worldwide. Melatonin, an indoleamine produced in pineal gland, shows anticancer effects on a variety of cancers, especially CRC. After clarifying the pathophysiology of CRC, the association of circadian rhythm with CRC, and the relationship between shift work and the incidence of CRC is reviewed. Next, we review the role of melatonin receptors in CRC and the relationship between inflammation and CRC. Also included is a discussion of the mechanism of gene regulation, control of cell proliferation, apoptosis, autophagy, antiangiogenesis and immunomodulation in CRC by melatonin. A review of the drug synergy of melatonin with other anticancer drugs suggests its usefulness in combination therapy. In summary, the information compiled may serve as comprehensive reference for the various mechanisms of action of melatonin against CRC, and as a guide for the design of future experimental research and for advancing melatonin as a therapeutic agent for CRC.