Differential levels of circulating RNAs prior to endometrial cancer diagnosis.

Endometrial cancer (EC) is one of the most common female cancers and there is currently no routine screening strategy for early detection. An altered abundance of circulating microRNAs (miRNAs) and other RNA classes have the potential as early cancer biomarkers. We analyzed circulating RNA levels using small RNA sequencing, targeting RNAs in the size range of 17-47 nucleotides, in EC patients with samples collected prior to diagnosis compared to cancer-free controls. The analysis included 316 cases with samples collected 1-11 years prior to EC diagnosis, and 316 matched controls, both from the Janus Serum Bank cohort in Norway. We identified differentially abundant (DA) miRNAs, isomiRs, and small nuclear RNAs between EC cases and controls. The top EC DA miRNAs were miR-155-5p, miR-200b-3p, miR-589-5p, miR-151a-5p, miR-543, miR-485-5p, miR-625-p, and miR-671-3p. miR-200b-3p was previously reported to be among one of the top miRNAs with higher abundance in EC cases. We observed 47, 41, and 32 DA miRNAs for EC interacting with BMI, smoking status, and physical activity, respectively, including two miRNAs (miR-223-3p and miR-29b-3p) interacting with all three factors. The circulating RNAs are altered and show temporal dynamics prior to EC diagnosis. Notably, DA miRNAs for EC had the lowest q-value 4.39-6.66 years before diagnosis. Enrichment analysis of miRNAs showed that signaling pathways Fc epsilon RI, prolactin, toll-like receptor, and VEGF had the strongest associations.

Characterization of ovarian cancer survival by histotype and stage: A nationwide study in Norway.

Contemporary population-based data on ovarian cancer survival using current subtype classifications and by surgical status are sparse. We evaluated 1-, 3-, 5- and 7-year relative (and overall) survival, and excess hazards in patients with borderline tumors or invasive epithelial ovarian cancer diagnosed 2012 to 2021 in a nationwide registry-based cohort in Norway. Outcomes were evaluated by histotype, FIGO stage, cytoreduction surgery and residual disease. Overall survival was evaluated for non-epithelial ovarian cancer. Survival of women with borderline ovarian tumors was excellent (≥98.0% 7-year relative survival). Across all evaluated invasive epithelial ovarian cancer histotypes, 7-year relative survival for cases diagnosed with stages I or II disease was ≥78.3% (stage II high-grade serous). Survival for ovarian cancers diagnosed at stage ≥III differed substantially by histotype and time since diagnosis (eg, stage III, 5-year relative survival from 27.7% [carcinosarcomas] to 76.2% [endometrioid]). Overall survival for non-epithelial cases was good (91.8% 5-year overall survival). Women diagnosed with stage III or IV invasive epithelial ovarian cancer and with residual disease following cytoreduction surgery had substantially better survival than women not operated. These findings were robust to restriction to women with high reported functional status scores. Patterns for overall survival were similar to those for relative survival. We observed relatively good survival with early stage at diagnosis even for the high grade serous histotype. Survival for patients diagnosed at stage ≥III invasive epithelial ovarian cancer was poor for all but endometrioid disease. There remains an urgent need for strategies for risk reduction and earlier detection, together with effective targeted treatments.

Dynamic and static circulating cancer microRNA biomarkers - a validation study.

For cancers and other pathologies, early diagnosis remains the most promising path to survival. Profiling of longitudinal cohorts facilitates insights into trajectories of biomarkers. We measured microRNA expression in 240 serum samples from patients with colon, lung, and breast cancer and from cancer-free controls. Each patient provided at least two serum samples, one prior to diagnosis and one following diagnosis. The median time interval between the samples was 11.6 years. Using computational models, we evaluated the circulating profiles of 21 microRNAs. The analysis yielded two sets of biomarkers, static ones that show an absolute difference between certain cancer types and controls and dynamic ones where the level over time provided higher diagnostic information content. In the first group, miR-99a-5p stands out for all three cancer types. In the second group, miR-155-5p allows to predict lung cancers and colon cancers. Classification in samples from cancer and non-cancer patients using gradient boosted trees reached an average accuracy of 79.9%. The results suggest that individual change over time or an absolute value at one time point may predict a disease with high specificity and sensitivity.

Circulating free testosterone and risk of aggressive prostate cancer: Prospective and Mendelian randomisation analyses in international consortia.

Previous studies had limited power to assess the associations of testosterone with aggressive disease as a primary endpoint. Further, the association of genetically predicted testosterone with aggressive disease is not known. We investigated the associations of calculated free and measured total testosterone and sex hormone-binding globulin (SHBG) with aggressive, overall and early-onset prostate cancer. In blood-based analyses, odds ratios (OR) and 95% confidence intervals (CI) for prostate cancer were estimated using conditional logistic regression from prospective analysis of biomarker concentrations in the Endogenous Hormones, Nutritional Biomarkers and Prostate Cancer Collaborative Group (up to 25 studies, 14 944 cases and 36 752 controls, including 1870 aggressive prostate cancers). In Mendelian randomisation (MR) analyses, using instruments identified using UK Biobank (up to 194 453 men) and outcome data from PRACTICAL (up to 79 148 cases and 61 106 controls, including 15 167 aggressive cancers), ORs were estimated using the inverse-variance weighted method. Free testosterone was associated with aggressive disease in MR analyses (OR per 1 SD = 1.23, 95% CI = 1.08-1.40). In blood-based analyses there was no association with aggressive disease overall, but there was heterogeneity by age at blood collection (OR for men aged <60 years 1.14, CI = 1.02-1.28; Phet  = .0003: inverse association for older ages). Associations for free testosterone were positive for overall prostate cancer (MR: 1.20, 1.08-1.34; blood-based: 1.03, 1.01-1.05) and early-onset prostate cancer (MR: 1.37, 1.09-1.73; blood-based: 1.08, 0.98-1.19). SHBG and total testosterone were inversely associated with overall prostate cancer in blood-based analyses, with null associations in MR analysis. Our results support free testosterone, rather than total testosterone, in the development of prostate cancer, including aggressive subgroups.

Prediagnostic circulating levels of sex hormones and survival in esophageal adenocarcinoma.

Sex hormonal differences may contribute to the strong male predominance in esophageal adenocarcinoma (EAC), but whether sex hormone levels influence survival in EAC is unstudied. Our study aimed to assess associations between prediagnostic sex hormone levels and survival in EAC. In a population-based cohort study, 244 male EAC patients from the Janus Serum Bank Cohort in Norway were followed up through 2018. Associations between prediagnostic serum levels of 12 sex hormone measures and disease-specific mortality were assessed using multivariable Cox regression, providing hazard ratios (HR) with 95% confidence intervals (CI) adjusted for age, calendar year, body mass index, tobacco smoking, physical activity and surgical resection. Higher levels of sex hormone-binding globulin (SHBG) indicated decreased disease-specific mortality (HR 0.68, 95% CI 0.44-1.07, highest vs lowest tertile). In stratified analyses by surgery, such associations remained in nonoperated patients (HR 0.58, 95% CI 0.35-0.96, highest vs lowest tertile), but not in operated patients. Higher levels of follicle-stimulating hormone (FSH) were associated with increased disease-specific mortality in an exposure-response pattern; HRs for the middle and highest tertiles vs the lowest tertile were 1.35 (95% CI 0.89-2.05) and 1.61 (95% CI 1.06-2.43), respectively. No clear associations were observed with serum levels of dehydroepiandrosterone sulfate, luteinizing hormone, prolactin, testosterone, 17-OH-progesterone, progesterone, estradiol, androstenedione, testosterone:estradiol ratio or free testosterone index. These findings suggest that higher endogenous levels of SHBG and lower levels of FSH may increase the survival in EAC. The other 10 examined sex hormone measures may not influence the survival.

Prediagnostic serum sCD27 and sCD30 in serial samples and risks of non-Hodgkin lymphoma subtypes.

Elevated prediagnostic serum levels of the immune activation markers sCD27 and sCD30 have been associated with non-Hodgkin lymphoma (NHL). However, the use of a single sample per participant in these studies has limited etiologic inferences. We report findings, overall and by NHL subtype, from a case-control analysis (422 cases, 434 controls) within the Janus Serum Bank with two samples per subject collected on average 5 years apart. Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) was associated with elevated sCD27 in the later, but not earlier, prediagnostic sample (odds ratio [OR] 4.2, 95% confidence interval [CI] 1.5-11.6 and 1.7, 0.7-4.7 per log increase, respectively) in analyses adjusting for both analytes, while follicular lymphoma (FL) was associated with elevated sCD30 in both the later and earlier samples (OR 2.9, 95% CI 1.4-4.4 and 2.3, 1.2-4.4, respectively). CLL/SLL cases were significantly more likely than controls to have higher sCD27 in the later vs. earlier sample (OR 1.4, 95% CI 1.1-1.9 per standard deviation increase); no such difference in sCD30 was apparent for FL. In a joint analysis, NHL cases were more likely than controls to have below-median sCD27 in the earlier sample and above-median sCD27 in the later sample (OR 1.5, 95% CI 1.0-2.3). For sCD30, the association between sCD30 and FL was confined to subjects with above-median analyte levels in both samples (OR 2.5, 95% CI 1.1-5.9). Our findings are compatible with elevated sCD27 representing a disease-induced effect and sCD30 representing a marker of increased FL susceptibility.

Prediagnostic blood levels of organochlorines and risk of non-Hodgkin lymphoma in three prospective cohorts in China and Singapore.

Specific organochlorines (OCs) have been associated with non-Hodgkin lymphoma (NHL) with varying degrees of evidence. These associations have not been evaluated in Asia, where the high exposure and historical environmental contamination of certain OC pesticides (e.g., dichlorodiphenyltrichloroethane [DDT], hexachlorocyclohexane [HCH]) are different from Western populations. We evaluated NHL risk and prediagnostic blood levels of OC pesticides/metabolites and polychlorinated biphenyl congeners in a case-control study of 167 NHL cases and 167 controls nested within three prospective cohorts in Shanghai and Singapore. Conditional logistic regression was used to analyze lipid-adjusted OC levels and NHL risk. Median levels of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), the primary DDT metabolite, and ß-HCH were up to 12 and 65 times higher, respectively, in samples from the Asian cohorts compared to several cohorts in the United States and Norway. An increased risk of NHL was observed among those with higher ß-HCH levels both overall (3rd vs. 1st tertile OR = 1.8, 95%CI = 1.0-3.2; ptrend = 0.049) and after excluding cases diagnosed within 2 years of blood collection (3rd vs. 1st tertile OR = 2.0, 95%CI = 1.1-3.9; ptrend = 0.03), and the association was highly consistent across the three cohorts. No significant associations were observed for other OCs, including p,p'-DDE. Our findings provide support for an association between ß-HCH blood levels and NHL risk. This is a concern because substantial quantities of persistent, toxic residues of HCH are present in the environment worldwide. Although there is some evidence that DDT is associated with NHL, our findings for p,p'-DDE do not support an association.

Circulating Sex Hormone Levels and Risk of Esophageal Adenocarcinoma in a Prospective Study in Men.

OBJECTIVES: Sex hormones have been hypothesized to explain the strong male predominance in esophageal adenocarcinoma, but evidence is needed. This study examined how circulating sex hormone levels influence future risk of esophageal adenocarcinoma. METHODS: This case-control study was nested in a prospective Norwegian cohort (Janus Serum Bank Cohort), including 244 male patients with esophageal adenocarcinoma and 244 male age-matched control participants. Associations between prediagnostic circulating levels of 12 sex hormones and risk of esophageal adenocarcinoma were assessed using conditional logistic regression. In addition, a random-effect meta-analysis combined these data with a similar prospective study for 5 sex hormones. RESULTS: Decreased odds ratios (ORs) of esophageal adenocarcinoma were found comparing the highest with lowest quartiles of testosterone (OR = 0.44, 95% confidence interval [CI] 0.22-0.88), testosterone:estradiol ratio (OR = 0.37, 95% CI 0.19-0.72), and luteinizing hormone (OR = 0.50, 95% CI 0.30-0.98), after adjustment for tobacco smoking and physical activity. These associations were attenuated after further adjustment for body mass index (OR = 0.56, 95% CI 0.27-1.13 for testosterone; OR = 0.46, 95% CI 0.23-0.91 for testosterone:estradiol ratio; OR = 0.55, 95% CI 0.29-1.08 for luteinizing hormone). No associations were observed for sex hormone-binding globulin, dehydroepiandrosterone sulfate, follicle-stimulating hormone, prolactin, 17-OH progesterone, progesterone, androstenedione, or free testosterone index. The meta-analysis showed an inverse association between testosterone levels and risk of esophageal adenocarcinoma (pooled OR for the highest vs lowest quartile = 0.60, 95% CI 0.38-0.97), whereas no associations were identified for androstenedione, sex hormone-binding globulin, estradiol, or testosterone:estradiol ratio. DISCUSSION: Higher circulating testosterone levels may decrease the risk of esophageal adenocarcinoma in men.

Competitive learning suggests circulating miRNA profiles for cancers decades prior to diagnosis.

MicroRNAs are regulators of gene expressionand may be key markers in liquid biopsy.Early diagnosis is an effective means to increase patients' overall survival. We generated genome-wide miRNA profiles from serum of patients and controls from the population-based Janus Serum Bank (JSB) and analysed them by bioinformatics and artificial intelligence approaches. JSB contains sera from 318,628 originally healthy persons, more than 96,000 of whom developed cancer. We selected 210 serum samples from patients with lung, colon or breast cancer at three time points prior to diagnosis (up to 32 years prior to diagnosis with median 5 years interval between TPs), one time-point after diagnosis and from individually matched controls. The controls were matched on age and year of all pre-diagnostic sampling time-points for the corresponding case. Using ANOVA we report 70 significantly deregulated markers (adjusted p-value<0.05). The driver for the significance was the diagnostic time point (miR-575, miR-6821-5p, miR-630 with adjusted p-values<10-10). Further, 91miRNAs were differently expressed in pre-diagnostic samples as compared to controls (nominal p < 0.05). Self-organized maps (SOMs)indicated larges effects in lung cancer samples while breast cancer samples showed the least pronounced changes. SOMsalsohighlighted cancer and time point specific miRNA dys-regulation. Intriguingly, a detailed breakdown of the results highlighted that 51% of all miRNAs were highly specific, either for a time-point or a cancer entity. Pathway analysis highlighted 12 pathways including Hipo signalling and ABC transporters.Our results indicate that tumours may be indicated by serum miRNAs decades prior the clinical manifestation.

Prediagnostic serum concentrations of organochlorine pesticides and non-Hodgkin lymphoma: A nested case-control study in the Norwegian Janus Serum Bank Cohort.

BACKGROUND: Much of the marked increase in incidence of non-Hodgkin lymphoma (NHL) over the past few decades remains unexplained. Organochlorines, including organochlorine pesticides (OCPs), have been implicated as possible contributors to the increase, but the evidence is inconsistent. OBJECTIVES: To investigate the relation between pre-diagnostic levels of OCPs and risk of NHL in a case-control study nested within the population-based Janus Serum Bank Cohort in Norway. METHODS: Prediagnostic concentrations of 11 OCPs or OCP metabolites were measured in baseline blood samples collected between 1972 and 1978 from 190 cases and 190 controls matched on sex, county, age at blood draw, and date of blood draw. We conducted conditional logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for each quartile of lipid-corrected OCP/metabolite relative to the lowest quartile. RESULTS: We observed non-significantly elevated ORs across quartiles of ß-hexachlorocyclohexane compared to the lowest quartile (OR range: 1.40-1.82) although with no apparent monotonic exposure-response relationship. We also found an inverse association between risk of NHL and o,p'-DDT (OR for Q4 vs. Q1 = 0.44, 95% CI: 0.19, 1.01; p-trend = 0.05). In analyses stratified by age at blood collection and duration of follow-up, several other analytes, primarily chlordane-related compounds, showed inverse associations among younger participants or those with longer follow-up time between blood draw and NHL diagnosis. CONCLUSIONS: We found only limited evidence of positive association between selected OCPs and development of NHL.

A high-resolution map of the human small non-coding transcriptome.

Motivation: Although the amount of small non-coding RNA-sequencing data is continuously increasing, it is still unclear to which extent small RNAs are represented in the human genome. Results: In this study we analyzed 303 billion sequencing reads from nearly 25 000 datasets to answer this question. We determined that 0.8% of the human genome are reliably covered by 874 123 regions with an average length of 31 nt. On the basis of these regions, we found that among the known small non-coding RNA classes, microRNAs were the most prevalent. In subsequent steps, we characterized variations of miRNAs and performed a staged validation of 11 877 candidate miRNAs. Of these, many were actually expressed and significantly dysregulated in lung cancer. Selected candidates were finally validated by northern blots. Although isolated miRNAs could still be present in the human genome, our presented set likely contains the largest fraction of human miRNAs. Contact: c.backes@mx.uni-saarland.de or andreas.keller@ccb.uni-saarland.de. Supplementary information: Supplementary data are available at Bioinformatics online.

Circulating isoflavone and lignan concentrations and prostate cancer risk: a meta-analysis of individual participant data from seven prospective studies including 2,828 cases and 5,593 controls.

Phytoestrogens may influence prostate cancer development. This study aimed to examine the association between prediagnostic circulating concentrations of isoflavones (genistein, daidzein, equol) and lignans (enterolactone and enterodiol) and the risk of prostate cancer. Individual participant data were available from seven prospective studies (two studies from Japan with 241 cases and 503 controls and five studies from Europe with 2,828 cases and 5,593 controls). Because of the large difference in circulating isoflavone concentrations between Japan and Europe, analyses of the associations of isoflavone concentrations and prostate cancer risk were evaluated separately. Prostate cancer risk by study-specific fourths of circulating concentrations of each phytoestrogen was estimated using multivariable-adjusted conditional logistic regression. In men from Japan, those with high compared to low circulating equol concentrations had a lower risk of prostate cancer (multivariable-adjusted OR for upper quartile [Q4] vs. Q1 = 0.61, 95% confidence interval [CI] = 0.39-0.97), although there was no significant trend (OR per 75 percentile increase = 0.69, 95 CI = 0.46-1.05, ptrend = 0.085); Genistein and daidzein concentrations were not significantly associated with risk (ORs for Q4 vs. Q1 = 0.70, 0.45-1.10 and 0.71, 0.45-1.12, respectively). In men from Europe, circulating concentrations of genistein, daidzein and equol were not associated with risk. Circulating lignan concentrations were not associated with the risk of prostate cancer, overall or by disease aggressiveness or time to diagnosis. There was no strong evidence that prediagnostic circulating concentrations of isoflavones or lignans are associated with prostate cancer risk, although further research is warranted in populations where isoflavone intakes are high.

A comprehensive profile of circulating RNAs in human serum.

Non-coding RNA (ncRNA) molecules have fundamental roles in cells and many are also stable in body fluids as extracellular RNAs. In this study, we used RNA sequencing (RNA-seq) to investigate the profile of small non-coding RNA (sncRNA) in human serum. We analyzed 10 billion Illumina reads from 477 serum samples, included in the Norwegian population-based Janus Serum Bank (JSB). We found that the core serum RNA repertoire includes 258 micro RNAs (miRNA), 441 piwi-interacting RNAs (piRNA), 411 transfer RNAs (tRNA), 24 small nucleolar RNAs (snoRNA), 125 small nuclear RNAs (snRNA) and 123 miscellaneous RNAs (misc-RNA). We also investigated biological and technical variation in expression, and the results suggest that many RNA molecules identified in serum contain signs of biological variation. They are therefore unlikely to be random degradation by-products. In addition, the presence of specific fragments of tRNA, snoRNA, Vault RNA and Y_RNA indicates protection from degradation. Our results suggest that many circulating RNAs in serum can be potential biomarkers.

A nested case-control study of polychlorinated biphenyls, organochlorine pesticides, and thyroid cancer in the Janus Serum Bank cohort.

BACKGROUND: Polychlorinated biphenyls (PCBs) and organochlorine pesticides have been associated with altered thyroid hormone levels in humans, but their relationship with thyroid cancer is unknown. METHODS: We conducted a nested case-control study of thyroid cancer in the Norwegian Janus Serum Bank cohort using pre-diagnostic blood samples from 1972 to 1985. Incident thyroid cancer (n = 108) was ascertained through 2008. Controls were matched 2:1 by age, date of blood draw, gender, and county. We used gas chromatography/mass spectrometry to quantify 36 PCB congeners and metabolites of pesticides DDT, chlordane, hexachlorocyclohexane, and hexachlorobenzene. PCBs and pesticide metabolites were evaluated individually and summed by degree of chlorination and parent compound, respectively. Odds ratios (OR) and 95% confidence intervals (CI) were computed using conditional logistic regression per specified increase in lipid-adjusted concentration. We additionally stratified analyses by birth cohort (1923-1932, 1933-1942, 1943-1957). RESULTS: Increasing concentration of DDT metabolites (ORper 1000 ng/g = 0.80, 95%CI = 0.66-0.98) was inversely associated with thyroid cancer. Associations for PCBs were null or in inverse direction. We observed interactions for total PCBs, moderately-chlorinated PCBs, and chlordane metabolites with birth cohort (p ≤ 0.04). Among participants born 1943-1957, total PCBs (ORper 100 ng/g = 1.25, 95%CI = 1.00-1.56), moderately-chlorinated PCBs (ORper 100 ng/g = 1.31, 95%CI = 1.01-1.70), and chlordane metabolites (ORper 10 ng/g = 1.78, 95%CI = 1.09-2.93) were positively associated with thyroid cancer. For individuals born before 1943, associations were generally null or in the inverse direction. CONCLUSIONS: Emissions of PCBs and OC pesticides varied over time. Different risk patterns by birth cohort suggest the potential importance of timing of exposure in thyroid cancer risk. Further evaluation of these associations is warranted.

Survival after secondary cytoreductive surgery and chemotherapy compared with chemotherapy alone for first recurrence in patients with platinum-sensitive epithelial ovarian cancer and no residuals after primary treatment. A registry-based study.

INTRODUCTION: The aim of this study was to investigate whether secondary cytoreductive surgery and platinum-based chemotherapy improved survival among patients with recurrent, platinum-sensitive epithelial ovarian cancer compared with those who received platinum-based chemotherapy alone, and to identify possible predictors for selection to secondary cytoreductive surgery. MATERIAL AND METHODS: We included 397 patients who had a primary diagnosis of FIGO stage I-IV epithelial ovarian cancer recorded in the Cancer Registry of Norway between 1 January 2002 and 31 December 2012, received primary surgery with no residuals followed by platinum-based chemotherapy, had first recurrence six or more months after completion of primary platinum-based chemotherapy, and received secondary treatment with either secondary cytoreductive surgery and platinum-based chemotherapy (secondary cytoreductive surgery+platinum-based chemotherapy group) or platinum-based chemotherapy alone (platinum-based chemotherapy group). Outcomes were progression-free survival to second recurrence or death and overall survival. Hazard ratios were estimated using multivariable Cox regression. RESULTS: There were 75 patients in the secondary cytoreductive surgery+platinum-based chemotherapy group in whom complete resection was achieved for 60 (80%), and 322 patients in the platinum-based chemotherapy group. Both progression-free survival (hazard ratio 0.45, 95% confidence interval 0.32-0.62) and overall survival (hazard ratio 0.50, 95% confidence interval 0.32-0.70) were improved in the secondary cytoreductive surgery+platinum-based chemotherapy compared with the platinum-based chemotherapy group. A survival benefit was only seen in patients with no residuals at secondary cytoreductive surgery. CONCLUSIONS: In selected epithelial ovarian cancer patients with no residuals after primary surgery and a recurrent, platinum-sensitive tumor, the complete resection of recurrent tumor at secondary cytoreductive surgery improves progression-free survival and overall survival. Our results suggest that a long treatment-free interval and non-disseminated lesions (three or fewer lesions) on radiological images could be useful predictors for complete resection at secondary cytoreductive surgery.

Sources to variability in circulating human miRNA signatures.

An increasing number of studies propose circulating microRNAs (miRNAs) as biomarkers for a large number of human diseases including cancer, cardiovascular diseases, neurologic pathologies and others. To further validate miRNA as biomarkers it is indispensable to understand the variability of circulating miRNAs in healthy individuals. We determined the longitudinal miRNomes of 90 serum samples from the Janus Serum Bank in Norway, which have been stored between 23 and 40 y at -25 °Celsius. We profiled 3 serum samples with microarrays for 30 individuals, each. For each individual the samples were collected with a time interval of approximately 5 y. This design allowed insights into inter-individual variability, age dependent miRNA variability and the impact of storage length and pre-processing. A significant proportion of the miRNome was affected by the age of the blood donor and a not negligible, albeit small, part of the miRNome by the storage time. A substantial part of miRNAs was differentially abundant between individuals, independent of the time when samples were collected. Stepwise filtering of the 529 miRNAs that were detected in the serum samples showed 168 miRNAs with differential abundance depending on the time point analyzed, 56 miRNAs differentially abundant between individuals, and 169 miRNAs with an abundance depending on the sampling procedure. While these groups of miRNAs contain generally interesting and biologically important miRNAs, the remaining 135 miRNAs constitute very promising biomarker candidates as they show an overall low variability between healthy individuals, a likewise overall low variability across a longer life span, and a high independence of the sampling process and the storage length.

Effect of multiple freeze-thaw cycles on selected biochemical serum components.

BACKGROUND: To maintain the best performance a frozen serum sample should be thawed once to prevent repeated freeze-thaw cycles. Archival biobanks often have one tube of a sample available, causing repeated freeze-thaw cycles when the sample is used in multiple research projects. In this study, we investigated potential effects of freeze-thaw cycles on several biochemical components in serum. METHODS: Serum from 40 fasting donors of both genders, aged 30-60 years, were frozen at -25 °C. Aliquots of the 40 different samples went through 1, 2, 3, 4, 5 and 10 thaws, respectively. They were analyzed after 3 month of storage for 15 serum components including electrolytes and metabolites, proteins and enzymes, lipids, hormones and vitamins. One-way analyses of variance (ANOVA) with repeated measurements and equivalence tests were used to examine differences in component levels. RESULTS: Albumin, aspartate-aminotransferase (ASAT), cholesterol, creatinine, C-reactive protein, glucose, immunoglobulin G, potassium, testosterone, triglycerides, urea and vitamin B12 levels did not show significant difference for pairwise comparisons after 10 repeated thaws. Although albumin, ASAT, bilirubin, potassium, sodium, testosterone and thyroid stimulating hormone (TSH) showed overall statistically significant changes in serum levels, only bilirubin, sodium and TSH were significant for the pairwise comparisons investigated. Clinical significance were shown for albumin, ASAT, bilirubin, sodium and testosterone. CONCLUSIONS: Twelve components (albumin, ASAT, cholesterol, creatinine, C-reactive protein, glucose, immunoglobulin G, potassium, testosterone, triglycerides, urea and vitamin B12) were robust to 10 repeated thaws compared to baseline level. Three components (bilirubin, sodium and TSH) showed statistical significant difference for pairwise comparisons, however, TSH was not clinically affected.

Serum biomarkers of polyomavirus infection and risk of lung cancer in never smokers.

BACKGROUND: Lung cancer in never smokers is a significant contributor of cancer mortality worldwide. In this analysis, we explored the role of nine human polyomaviruses, including JC virus (JCV), BK virus (BKV) and Merkel cell virus (MCV), in lung cancer development in never smokers as there are data to support that polyomaviruses are potentially carcinogenic in the human lung. METHODS: We used multiplex serology to detect serum antibodies to polyomaviruses in a nested case-control design combining lung cancer cases and controls from four cohort studies - NYU Women's Health Study (NYU-WHS), Janus Serum Bank, Shanghai Women's Health Study and Singapore Chinese Health Study (SCHS). RESULTS: The final analyses included 511 cases and 508 controls. Seroprevalence for each polyomavirus showed significant heterogeneity by study, but overall there were no statistically significant differences between cases and controls. In total, 69.1% of the cases and 68.7% of the controls were seropositive for JCV VP1 antibody. Seropositivity for BKV was higher at 89.0% in cases and 89.8% in controls and lower for MCV at 59.3% in cases and 61.6% in controls. Similar results were obtained after adding an additional retrospective case-control study (Xuanwei study) to the analysis. CONCLUSIONS: Our results do not support the hypothesis that seropositivity for polyomaviruses is associated with increased lung cancer risk in never smokers. Future research to evaluate relationship between polyomavirus infection and lung carcinogenesis should focus more on evaluating the presence of virus or viral nucleic acids (DNA or RNA) in lung tumour samples.

Pre-diagnostic serum levels of EGFR and ErbB2 and genetic glioma risk variants: a nested case-control study.

Genetic variants have been associated with the risk of developing glioma, but functional mechanisms on disease phenotypic traits remain to be investigated. One phenotypic trait of glioblastoma is the mutation and amplification of the epidermal growth factor receptor (EGFR) gene. We investigated associations between pre-diagnostic serum protein concentrations of EGFR and ErbB2, both members of the EGFR family, and future risk of glioma. Further, we studied if EGFR glioma risk variants were associated with EGFR and ErbB2 serum levels. We assessed the associations between genetic glioma risk variants and serum concentrations of EGFR and ErbB2, as measured in pre-diagnostic cohort serum samples of 593 glioma patients and 590 matched cancer-free controls. High serum EGFR and ErbB2 levels were associated with risk of developing glioblastoma (P = 0.008; OR = 1.58, 95 % CI = 1.13-2.22 and P = 0.017, OR = 1.63, 95 % CI = 1.09-2.44, respectively). High serum ErbB2 concentration was also associated with glioma risk overall (P = 0.049; OR = 1.39, 95 % CI = 1.00-1.93). Glioma risk variants were not associated with high serum protein abundance. In contrast, the EGFR risk variant rs4947986 (T) was correlated with decreased EGFR serum levels (study cohort P = 0.024 and controls P = 0.009). To our knowledge, this is the first study showing an association of EGFR and ErbB2 serum levels with glioma more than a decade before diagnosis, indicating that EGFR and ErbB2 serum proteins are important in early gliomagenesis. However, we did not find evidence that glioma risk variants were associated with high pre-diagnostic serum concentrations of EGFR and ErbB2.

Bayes and empirical Bayes methods for reduced rank regression models in matched case-control studies.

Matched case-control studies are popular designs used in epidemiology for assessing the effects of exposures on binary traits. Modern studies increasingly enjoy the ability to examine a large number of exposures in a comprehensive manner. However, several risk factors often tend to be related in a nontrivial way, undermining efforts to identify the risk factors using standard analytic methods due to inflated type-I errors and possible masking of effects. Epidemiologists often use data reduction techniques by grouping the prognostic factors using a thematic approach, with themes deriving from biological considerations. We propose shrinkage-type estimators based on Bayesian penalization methods to estimate the effects of the risk factors using these themes. The properties of the estimators are examined using extensive simulations. The methodology is illustrated using data from a matched case-control study of polychlorinated biphenyls in relation to the etiology of non-Hodgkin's lymphoma.