A Prospective Study on the Roles of the Lymphocyte-to-Monocyte Ratio (LMR), Neutrophil-to-Lymphocyte Ratio (NLR), and Platelet-to-Lymphocyte Ratio (PLR) in Patients with Locally Advanced Rectal Cancer.

Rectal cancer constitutes over one-third of all colorectal cancers (CRCs) and is one of the leading causes of cancer-related deaths in developed countries. In order to identify high-risk patients and better adjust therapies, new markers are needed. Systemic inflammatory response (SIR) markers such as LMR, NLR, and PLR have proven to be highly prognostic in many malignancies, including CRC; however, their roles in locally advanced rectal cancer (LARC) are conflicting and lack proper validation. Sixty well-selected patients with LARC treated at the Maria Sklodowska-Curie National Research Institute of Oncology in Warsaw, Poland, between August 2017 and December 2020 were prospectively enrolled in this study. The reproducibility of the pre-treatment levels of the SIR markers, their correlations with clinicopathological characteristics, and their prognostic value were evaluated. There was a significant positive correlation between LMR and cancer-related inflammatory infiltrate (r = 0.38, p = 0.044) and PD-L1 expression in tumor cells, lymphocytes, and macrophages (combined positive score (CPS)) (r = 0.45, p = 0.016). The PLR level was correlated with nodal involvement (p = 0.033). The SIR markers proved to be only moderately reproducible and had no significant prognostic value. In conclusion, the LMR was associated with local cancer-related inflammation and PD-L1 expression in tumor microenvironments. The validity of SIR indices as biomarkers in LARC requires further investigation.

Narrow-band imaging vs Lugol chromoendoscopy in screening for esophageal squamous cell neoplasia: a randomized trial.

INTRODUCTION: To date, there is no established optimal method for endoscopic detection of esophageal squamous cell neoplasia in high­risk individuals. OBJECTIVES: We aimed to compare the performance of narrow­band imaging (NBI) and Lugol chromoendoscopy in screening for esophageal neoplasia among patients with a history of treatment for head and neck squamous cell cancer (HNSCC). PATIENTS AND METHODS: We randomly assigned 300 patients who had completed curative treatment for HNSCC at least 1 year prior to the inclusion to undergo either NBI or Lugol endoscopy (2:1 ratio). Following white­light examination of the esophagus, the assigned imaging study was performed, and biopsies were taken from any suspicious lesions identified using NBI or Lugol chromoendoscopy. The primary end point was positive predictive value (PPV) of the biopsied lesion for a diagnosis of esophageal neoplasia (high­grade intraepithelial neoplasia [HG­IEN] or invasive esophageal squamous cell carcinoma [ESCC]). The secondary end points included the number of biopsied lesions, duration of esophagus examination, and endoscopy tolerance. RESULTS: In 294 patients included in the final analysis (NBI, n = 204; Lugol chromoendoscopy, n = 90), we diagnosed 3 ESCCs (1.02%) and 2 HG­IENs (0.68%). The PPV of NBI and Lugol chromoendoscopy in per­lesion analysis was 7.69% (95% CI, 0.94%-25.1%) and 8.11% (95% CI, 1.7%-21.9%), respectively (P >0.99). NBI outperformed Lugol chromoendoscopy in terms of the rate of patients requiring biopsy (12.75% vs 41.11%; P = 0.003), duration of esophagus examination (3.5 min vs 5.15 min; P <0.001), and endoscopy tolerance assessed on the visual analog scale (25 mm vs 36.5 mm; P = 0.002). CONCLUSIONS: With a PPV comparable to that of Lugol chromoendoscopy, but a lower number of biopsies required, shorter examination time, and better patient tolerance, NBI could be considered the primary screening method for ESCC in patients with HNSCC.

Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death.

BACKGROUND: Although colonoscopy is widely used as a screening test to detect colorectal cancer, its effect on the risks of colorectal cancer and related death is unclear. METHODS: We performed a pragmatic, randomized trial involving presumptively healthy men and women 55 to 64 years of age drawn from population registries in Poland, Norway, Sweden, and the Netherlands between 2009 and 2014. The participants were randomly assigned in a 1:2 ratio either to receive an invitation to undergo a single screening colonoscopy (the invited group) or to receive no invitation or screening (the usual-care group). The primary end points were the risks of colorectal cancer and related death, and the secondary end point was death from any cause. RESULTS: Follow-up data were available for 84,585 participants in Poland, Norway, and Sweden - 28,220 in the invited group, 11,843 of whom (42.0%) underwent screening, and 56,365 in the usual-care group. A total of 15 participants had major bleeding after polyp removal. No perforations or screening-related deaths occurred within 30 days after colonoscopy. During a median follow-up of 10 years, 259 cases of colorectal cancer were diagnosed in the invited group as compared with 622 cases in the usual-care group. In intention-to-screen analyses, the risk of colorectal cancer at 10 years was 0.98% in the invited group and 1.20% in the usual-care group, a risk reduction of 18% (risk ratio, 0.82; 95% confidence interval [CI], 0.70 to 0.93). The risk of death from colorectal cancer was 0.28% in the invited group and 0.31% in the usual-care group (risk ratio, 0.90; 95% CI, 0.64 to 1.16). The number needed to invite to undergo screening to prevent one case of colorectal cancer was 455 (95% CI, 270 to 1429). The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group (risk ratio, 0.99; 95% CI, 0.96 to 1.04). CONCLUSIONS: In this randomized trial, the risk of colorectal cancer at 10 years was lower among participants who were invited to undergo screening colonoscopy than among those who were assigned to no screening. (Funded by the Research Council of Norway and others; NordICC ClinicalTrials.gov number, NCT00883792.).

Correlation between Lymphocyte-to-Monocyte Ratio (LMR), Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR) and Tumor-Infiltrating Lymphocytes (TILs) in Left-Sided Colorectal Cancer Patients.

Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide. Novel markers are required in order to select high-risk patients and better adjust the treatment. Both peripheral and local markers of cancer-related inflammation (CRI) such as lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR) or platelet-to-lymphocyte ratio (PLR) and tumor-infiltrating lymphocytes (TILs) have been thoroughly investigated in recent years and deemed to be highly prognostic. We hypothesized that there is an association between local and peripheral CRI indices and that blood-based biomarkers may serve as a surrogate of TILs. We retrospectively analyzed 87 patients with locally advanced left-sided CRC treated with radical-intent surgery in the Maria Sklodowska-Curie National Research Institute of Oncology in Warsaw, Poland, between January 2014 and December 2015. Fifty patients were found eligible for the study. The patients were divided in terms of pre-treatment values of systemic inflammatory response (SIR) markers into LMR/NLR/PLR-high and low groups. We evaluated the resected specimens by immunohistochemistry in order to assess the densities of CD3+ and CD8+ lymphocytes in the center of the tumor and in the invasive margin. We found that the level of CD3+ lymphocytes in the center of the tumor was statistically significantly higher in patients with low pre-treatment NLR (p = 0.044); however, no correlation between any of the SIR markers and CD3+ or CD8+ TILs was observed. Five-year overall survival (OS) was longer in patients with high LMR (p < 0.001), low NLR (p = 0.001) and low PLR (p = 0.095). No correlation between the density of TILs and OS was demonstrated. In conclusion, based on our study, peripheral blood-based markers and CD3+ and CD8+ TILs are not interrelated.

Bean's syndrome (blue rubber bleb nevus syndrome - BRBNS) as a gastrointestinal bleeding - case report and review of the literature.

BRBNS is a rare syndrome of vascular malformations caused by the TEK mutation associated with numerous lesions of the skin and gastrointestinal tract. We present a case report of 41 year old man with severe anemia with recurrent bleedings. The detailed clinical, endoscopical and histopathological description is given as a wide range of differential diagnosis of vascular lesions based on pathophysiology and updated classification of vascular lesions. Clinicopathological diagnosis and treatment options of BRBNS are discussed.

Intravoxel incoherent motion MRI in evaluating inflammatory activity in ulcerative colitis: a pilot study.

BACKGROUND: A non-invasive tool for the assessment of ulcerative colitis (UC) activity is needed for treatment control. PURPOSE: To determine the efficacy of intravoxel incoherent motion (IVIM) in assessing inflammatory activity in UC. MATERIAL AND METHODS: In this prospective study, 20 adult patients underwent 3.0-T magnetic resonance imaging (MRI) IVIM diffusion-weighted imaging (DWI) with 10 b-values (0-900 s/mm2) 0-6 days after biopsies entailing colonoscopy. The inflammatory activity of large bowel segments was graded on endoscopy with Mayo score and on pathology with a six­grade classification system. IVIM­derived parameters (f, D, and D*) calculated from regions of interest placed within the bowel wall were correlated with both scores (56 and 34 bowel segments, respectively). Radiologists were blinded to endoscopy and pathology results. A T-test and Wilcoxon rank sum test was used in comparisons and receiver operating characteristic curve analysis was performed. RESULTS: Statistically significant differences were found between histopathologically inactive or mild activity and moderate to severe activity in f (respectively: mean = 0.19 and mean = 0.28, P = 0.024; area under the curve [AUC] = 0.723, sensitivity 0.82, specificity 0.59, accuracy 0.67 for a 0.185 cut-off value) and D (mean = 1.34 × 10-3mm2/s and mean = 1.07 × 10-3mm2/s, P = 0.0083; AUC = 0.735, sensitivity 0.91, specificity 0.54, accuracy 0.66 for cut-off value 1.24 × 10-3mm2/s). No significant difference in D* was noted. No significant correlation between Mayo endoscopic subscore, and f, D, nor D* was found. CONCLUSION: IVIM perfusion fraction correlates with UC activity and might represent emerging tool in assessment of inflammatory activity.

Argon plasma coagulation for Barrett's esophagus with low-grade dysplasia: a randomized trial with long-term follow-up on the impact of power setting and proton pump inhibitor dose.

BACKGROUND: This study evaluated the impact of power setting and proton pump inhibitor (PPI) dose on efficacy and safety of argon plasma coagulation (APC) of Barrett's esophagus (BE) with low-grade dysplasia (LGD). METHODS : 71 patients were randomized to APC with power set at 90 W or 60 W followed by 120 mg or 40 mg omeprazole. The primary outcome was the rate of complete (endoscopic and histologic) ablation of BE at 6 weeks. Secondary outcomes included safety and long-term efficacy. RESULTS : Complete ablation rate in the 90 W/120 mg, 90 W/40 mg, and 60 W/120 mg groups was 78 % (18/23; 95 % confidence interval [CI] 61-95), 60 % (15/25; 95 %CI 41-79), 74 % (17/23; 95 %CI 56-92), respectively, at 6 weeks and 70 % (16/23; 95 %CI 51-88), 52 % (13/25; 95 %CI 32-72), and 65 % (15/23; 95 %CI 46-85) at 2 years post-treatment (differences not significant). Additional APC was required in 28 patients (23 residual and 5 recurrent BE). At median follow-up of 108 months, 66/71 patients (93 %; 95 %CI 87-99) maintained complete ablation. No high-grade dysplasia or adenocarcinoma developed. Overall, adverse events (97 % mild) did not differ significantly between groups. Chest pain/discomfort was more frequent in patients receiving 90 W vs. 60 W power (P < 0.001). One patient had esophageal perforation and two developed stenosis. CONCLUSIONS: APC power setting and PPI dose did not impact efficacy and safety of BE ablation. Complete ablation of BE with LGD was durable in > 90 % of patients, without any evidence of neoplasia progression in the long term.

A stool test in patients with active ulcerative colitis helps exclude cytomegalovirus disease.

Objectives: In severe ulcerative colitis (UC) bowel biopsy is recommended to detect the cytomegalovirus (CMV) infection capable of complicating the course of the disease. Histopathology with immunohistochemistry (IHC) is time-consuming, and a blood polymerase chain reaction (PCR) for CMV DNA is used as an alternative, notwithstanding nothing more than a moderate correlation between the two. We aimed to detect CMV DNA in the stools of patients with active UC, and to compare the results with CMV IHC in bowel biopsies.Materials and methods: Measurement of CMV DNA in stools (copies/ml) entailed PCR, while biopsies assessed inflammation activity (Geboes scale), as well as counts of numbers of CMV IHC-positive cells/biopsy. The severity of UC was assessed using the Mayo score, stool calprotectin and concentrations of C-reactive protein in the blood.Results: 89 of the above pairs of tests for CMV were performed among 75 patients. CMV was detected in 36/89 stool specimens and 19/89 bowel biopsies. The sensitivity of the stool-CMV PCR was thus 84.7%, while specificity was of 71.4%. The negative predictive value was 94.3% and the positive predictive value 44.4%. No difference in the severity of UC was noted between the stool CMV DNA positive and negative groups. Similarly, there was no difference in the severity of UC between the CMV IHC positive and negative groups, except for the Geboes score, more often found to be higher in CMV IHC-positive patients (p = .002).Conclusions: CMV DNA was detected in the stools of 40.4% of patients with active UC. A negative test result may help to exclude bowel CMV disease.

Mutation Profiling of Premalignant Colorectal Neoplasia.

Accumulation of allelic variants in genes that regulate cellular proliferation, differentiation, and apoptosis may result in expansion of the aberrant intestinal epithelium, generating adenomas. Herein, we compared the mutation profiles of conventional colorectal adenomas (CNADs) across stages of progression towards early carcinoma. DNA was isolated from 17 invasive adenocarcinomas (ACs) and 58 large CNADs, including 19 with low-grade dysplasia (LGD), 21 with LGD adjacent to areas of high-grade dysplasia and/or carcinoma (LGD-H), and 28 with high-grade dysplasia (HGD). Ion AmpliSeq Comprehensive Cancer Panel libraries were prepared and sequenced on the Ion Proton. We identified 956 unique allelic variants; of these, 499 were considered nonsynonymous variants. Eleven genes (APC, KRAS, SYNE1, NOTCH4, BLNK, FBXW7, GNAS, KMT2D, TAF1L, TCF7L2, and TP53) were mutated in at least 15% of all samples. Out of frequently mutated genes, TP53 and BCL2 had a consistent trend in mutation prevalence towards malignancy, while two other genes (HNF1A and FBXW7) exhibited the opposite trend. HGD adenomas had significantly higher mutation rates than LGD adenomas, while LGD-H adenomas exhibited mutation frequencies similar to those of LGD adenomas. A significant increase in copy number variant frequency was observed from LGD through HGD to malignant samples. The profiling of advanced CNADs demonstrated variations in mutation patterns among colorectal premalignancies. Only limited numbers of genes were repeatedly mutated while the majority were altered in single cases. Most genetic alterations in adenomas can be considered early contributors to colorectal carcinogenesis.

Endoscopist biopsy rate as a quality indicator for outpatient gastroscopy: a multicenter cohort study with validation.

BACKGROUND AND AIMS: The diagnosis of gastric premalignant conditions (GPCs) relies on endoscopy with mucosal sampling. We hypothesized that the endoscopist biopsy rate (EBR) might constitute a quality indicator for EGD, and we have analyzed its association with GPC detection and the rate of missed gastric cancers (GCs). METHODS: We analyzed EGD databases from 2 high-volume outpatient units. EBR values, defined as the proportion of EGDs with ≥1 biopsy to all examinations were calculated for each endoscopist in Unit A (derivation cohort) and divided by the quartile values into 4 groups. Detection of GPC was calculated for each group and compared using multivariate clustered logistic regression models. Unit B database was used for validation. All patients were followed in the Cancer Registry for missed GCs diagnosed between 1 month and 3 years after EGDs with negative results. RESULTS: Sixteen endoscopists in Unit A performed 17,490 EGDs of which 15,340 (87.7%) were analyzed. EBR quartile values were 22.4% to 36.7% (low EBR), 36.8% to 43.7% (moderate), 43.8% to 51.6% (high), and 51.7% and 65.8% (very-high); median value 43.8%. The odds ratios for the moderate, high, and very-high EBR groups of detecting GPC were 1.6 (95% confidence interval [CI], 1.3-1.9), 2.0 (95% CI, 1.7-2.4), and 2.5 (95% CI, 2.1-2.9), respectively, compared with the low EBR group (P < .001). This association was confirmed with the same thresholds in the validation cohort. Endoscopists with higher EBR (≥43.8%) had a lower risk of missed cancer compared with those in the lower EBR group (odds ratio, 0.44; 95% CI, 0.20-1.00; P = .049). CONCLUSIONS: The EBR parameter is highly variable among endoscopists and is associated with efficacy in GPC detection and the rate of missed GCs.

Exome scale map of genetic alterations promoting metastasis in colorectal cancer.

BACKGROUND: Approximately 90% of colorectal cancer (CRC) deaths are caused by tumors ability to migrate into the adjacent tissues and metastase into distant organs. More than 40 genes have been causally linked to the development of CRC but no mutations have been associated with metastasis yet. To identify molecular basis of CRC metastasis we performed whole-exome and genome-scale transcriptome sequencing of 7 liver metastases along with their matched primary tumours and normal tissue. Multiple, spatially separated fragments of primary tumours were analyzed in each case. Uniformly malignant tissue specimen were selected with macrodissection, for three samples followed with laser microdissection. RESULTS: > 100 sequencing coverage allowed for detection of genetic alterations in subpopulation of tumour cells. Mutations in KRAS, APC, POLE, and PTPRT, previously associated with CRC development, were detected in most patients. Several new associations were identified, including PLXND1, CELSR3, BAHD1 and PNPLA6. CONCLUSIONS: We confirm the essential role of inflammation in CRC progression but question the mechanism of matrix metalloproteinases activation described in other work. Comprehensive sequencing data made it possible to associate genome-scale mutation distribution with gene expression patterns. To our knowledge, this is the first work to report such link in CRC metastasis context.

Detection of cytomegalovirus by immunohistochemistry of colonic biopsies and quantitative blood polymerase chain reaction: evaluation of agreement in ulcerative colitis.

OBJECTIVES: Cytomegalovirus (CMV) often reactivates in ulcerative colitis (UC). In diagnostics, along with immunohistochemistry (IHC) of colonic biopsies, blood CMV polymerase chain reaction (PCR) is gaining increasing application. We aimed to assess agreement between the density of infected colonic cells by IHC and the viral load in the blood by PCR. MATERIAL AND METHODS: We retrospectively identified patients with active UC or indeterminate colitis in whom blood CMV PCR had been performed while biopsies had been taken simultaneously. The latter were re-evaluated and the numbers of IHC-positive cells per square millimetre counted. RESULTS: The analyses extended to 234 sample pairs, among which there were 184 cases (78.6% of the total) in which IHC was equal to 0. The median among the remaining 50 non-zero values for IHC was 1.7 cells/mm2. PCR was equal to 0 in 192 cases (82.1%), while the median among the remaining 42 non-zero values was 4995.3 IU/ml. The Spearman correlation coefficient was 0.43 (p < .001). The area under the curve (AUC) values did not differ significantly between different IHC cut-offs. The highest AUC of 0.753 was obtained while predicting if IHC would be above the 3rd quartile (>5.6 cells/mm2), where PCR > 0 had a sensitivity of 0.615 and a specificity of 0.846. CONCLUSIONS: In active CMV colitis, the specificity and negative predictive value of blood PCR are high, while the sensitivity grows with the intensity of colon infection. A highly positive result could justify the administration of antiviral treatment being brought forward in selected patients.

Challenges in Stratifying the Molecular Variability of Patient-Derived Colon Tumor Xenografts.

Colorectal cancer (CRC) is the second most common cancer in Europe and a leading cause of death worldwide. Patient-derived xenograft (PDX) models maintain complex intratumoral biology and heterogeneity and therefore remain the platform of choice for translational drug discovery. In this study, we implanted 37 primary CRC tumors and five CRC cell lines into NU/J mice to develop xenograft models. Primary tumors and established xenografts were histologically assessed and surveyed for genetic variants and gene expression using a panel of 409 cancer-related genes and RNA-seq, respectively. More than half of CRC tumors (20 out of 37, 54%) developed into a PDX. Histological assessment confirmed that PDX grading, stromal components, inflammation, and budding were consistent with those of the primary tumors. DNA sequencing identified an average of 0.14 variants per gene per sample. The percentage of mutated variants in PDXs increased with successive passages, indicating a decrease in clonal heterogeneity. Gene Ontology analyses of 4180 differentially expressed transcripts (adj. p value < 0.05) revealed overrepresentation of genes involved in cell division and catabolic processes among the transcripts upregulated in PDXs; downregulated transcripts were associated with GO terms related to extracellular matrix organization, immune responses, and angiogenesis. Neither a transcriptome-based consensus molecular subtype (CMS) classifier nor three other predictors reliably matched PDX molecular subtypes with those of the primary tumors. In sum, both genetic and transcriptomic profiles differed between donor tumors and PDXs, likely as a consequence of subclonal evolution at the early phase of xenograft development, making molecular stratification of PDXs challenging.

Celiac disease on YouTube - a study of the Polish content available on the popular video-sharing website.

Celiac disease affects about 1% of the population. Since most Polish households have a broadband Internet connection, a lot of people use web resources to learn about health and disease. YouTube service (www.youtube.com) offers a lot of videos concerning celiac disease. However, the credibility of the Polish videos available on YouTube and concerning celiac disease has never been analyzed. AIM: The aim of the study was to determine whether the YouTube service offers valuable content for Polish people affected by celiac disease. MATERIALS AND METHODS: One hundred and fifty-four unique videos devoted to celiac disease and available in the Polish language were identified and critically assessed. Each video was categorized due to its topic(s), and evaluated for its credibility by two independent researchers. RESULTS: In general, 127 (82.5%) videos were found to be credible. The most credible categories of content presented organizations and events related to celiac disease/celiac society, followed by culinary recipes (100.0, 100.0, and 95.6% of credible videos, respectively). The least trustworthy categories were devoted to pathobiology and advertisements (55.6 and 54.3% of credible videos, respectively). CONCLUSIONS: YouTube service can serve as a supplementary source of knowledge for people affected by celiac disease, after careful selection of trustworthy content.

Clinicopathologic correlations of renal pathology in the adult population of Poland.

BACKGROUND: This is the first report on the epidemiology of biopsy-proven kidney diseases in Poland. METHODS: The Polish Registry of Renal Biopsies has collected information on all (n = 9394) native renal biopsies performed in Poland from 2009 to 2014. Patients' clinical data collected at the time of biopsy, and histopathological diagnoses were used for epidemiological and clinicopathologic analysis. RESULTS: There was a gradual increase in the number of native renal biopsies performed per million people (PMP) per year in Poland in 2009-14, starting from 36 PMP in 2009 to 44 PMP in 2014. A considerable variability between provinces in the mean number of biopsies performed in the period covered was found, ranging from 5 to 77 PMP/year. The most common renal biopsy diagnoses in adults were immunoglobulin A nephropathy (IgAN) (20%), focal segmental glomerulosclerosis (FSGS) (15%) and membranous glomerulonephritis (MGN) (11%), whereas in children, minimal change disease (22%), IgAN (20%) and FSGS (10%) were dominant. Due to insufficient data on the paediatric population, the clinicopathologic analysis was limited to patients ≥18 years of age. At the time of renal biopsy, the majority of adult patients presented nephrotic-range proteinuria (45.2%), followed by urinary abnormalities (38.3%), nephritic syndrome (13.8%) and isolated haematuria (1.7%). Among nephrotic patients, primary glomerulopathies dominated (67.6% in those 18-64 years of age and 62.4% in elderly patients) with leading diagnoses being MGN (17.1%), FSGS (16.2%) and IgAN (13.0%) in the younger cohort and MGN (23.5%), amyloidosis (18.8%) and FSGS (16.8%) in the elderly cohort. Among nephritic patients 18-64 years of age, the majority (55.9%) suffered from primary glomerulopathies, with a predominance of IgAN (31.3%), FSGS (12.7%) and crescentic GN (CGN) (11.1%). Among elderly nephritic patients, primary and secondary glomerulopathies were equally common (41.9% each) and pauci-immune GN (24.7%), CGN (20.4%) and IgAN (14.0%) were predominant. In both adult cohorts, urinary abnormalities were mostly related to primary glomerulopathies (66.8% in younger and 50% in elderly patients) and the leading diagnoses were IgAN (31.4%), FSGS (15.9%), lupus nephritis (10.7%) and FSGS (19.2%), MGN (15.1%) and pauci-immune GN (12.3%), respectively. There were significant differences in clinical characteristics and renal biopsy findings between male and female adult patients. CONCLUSIONS: The registry data focused new light on the epidemiology of kidney diseases in Poland. These data should be used in future follow-up and prospective studies.