A polygenic two-hit hypothesis for prostate cancer

Prostate cancer is one of the most heritable cancers. Hundreds of germline polymorphisms have been linked to prostate cancer diagnosis and prognosis. Polygenic risk scores can predict genetic risk of a prostate cancer diagnosis. Although these scores inform the probability of developing a tumor, it remains unknown how germline risk influences the tumor molecular evolution. We cultivated a cohort of 1250 localized European-descent patients with germline and somatic DNA profiling. Men of European descent with higher genetic risk were diagnosed earlier and had less genomic instability and fewer driver genes mutated. Higher genetic risk was associated with better outcome. These data imply a polygenic "two-hit" model where germline risk reduces the number of somatic alterations required for tumorigenesis. These findings support further clinical studies of polygenic risk scores as inexpensive and minimally invasive adjuncts to standard risk stratification. Further studies are required to interrogate generalizability to more ancestrally and clinically diverse populations.

Systematic Assessment of Tumor Purity and Its Clinical Implications

PURPOSE

The tumor microenvironment is complex, comprising heterogeneous cellular populations. As molecular profiles are frequently generated using bulk tissue sections, they represent an admixture of multiple cell types (including immune, stromal, and cancer cells) interacting with each other. Therefore, these molecular profiles are confounded by signals emanating from many cell types. Accurate assessment of residual cancer cell fraction is crucial for parameterization and interpretation of genomic analyses, as well as for accurately interpreting the clinical properties of the tumor.

MATERIALS AND METHODS

To benchmark cancer cell fraction estimation methods, 10 estimators were applied to a clinical cohort of 333 patients with prostate cancer. These methods include gold-standard multiobserver pathology estimates, as well as estimates inferred from genome, epigenome, and transcriptome data. In addition, two methods based on genomic and transcriptomic profiles were used to quantify tumor purity in 4,497 tumors across 12 cancer types. Bulk mRNA and microRNA profiles were subject to in silico deconvolution to estimate cancer cell-specific mRNA and microRNA profiles.

RESULTS

We present a systematic comparison of 10 tumor purity estimation methods on a cohort of 333 prostate tumors. We quantify variation among purity estimation methods and demonstrate how this influences interpretation of clinico-genomic analyses. Our data show poor concordance between pathologic and molecular purity estimates, necessitating caution when interpreting molecular results. Limited concordance between DNA- and mRNA-derived purity estimates remained a general pan-cancer phenomenon when tested in an additional 4,497 tumors spanning 12 cancer types.

CONCLUSION

The choice of tumor purity estimation method may have a profound impact on the interpretation of genomic assays. Taken together, these data highlight the need for improved assessment of tumor purity and quantitation of its influences on the molecular hallmarks of cancers.

Integrative pathway enrichment analysis of multivariate omics data

Multi-omics datasets represent distinct aspects of the central dogma of molecular biology. Such high-dimensional molecular profiles pose challenges to data interpretation and hypothesis generation. ActivePathways is an integrative method that discovers significantly enriched pathways across multiple datasets using statistical data fusion, rationalizes contributing evidence and highlights associated genes. As part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2658 cancers across 38 tumor types, we integrated genes with coding and non-coding mutations and revealed frequently mutated pathways and additional cancer genes with infrequent mutations. We also analyzed prognostic molecular pathways by integrating genomic and transcriptomic features of 1780 breast cancers and highlighted associations with immune response and anti-apoptotic signaling. Integration of ChIP-seq and RNA-seq data for master regulators of the Hippo pathway across normal human tissues identified processes of tissue regeneration and stem cell regulation. ActivePathways is a versatile method that improves systems-level understanding of cellular organization in health and disease through integration of multiple molecular datasets and pathway annotations.

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1-3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10-18.

Landscape of transcriptomic interactions between breast cancer and its microenvironment

Solid tumours comprise mixtures of tumour cells (TCs) and tumour-adjacent cells (TACs), and the intricate interconnections between these diverse populations shape the tumour’s microenvironment. Despite this complexity, clinical genomic profiling is typically performed from bulk samples, without distinguishing TCs from TACs. To better understand TC–TAC interactions, we computationally distinguish their transcriptomes in 1780 primary breast tumours. We show that TC and TAC mRNA abundances are divergently associated with clinical phenotypes, including tumour subtypes and patient survival. These differences reflect distinct responses of TCs and TACs to specific somatic driver mutations, particularly TP53. These data further elucidate how the molecular interplay between breast tumours and their microenvironment drives aggressive tumour phenotypes.

The transcriptomic profile of tumour-adjacent cells provides important information about tumour context but its clinical utility is unclear. Here, in breast cancer, Fox et al. show that the mRNA abundances of tumour and tumour-adjacent cells hold prognostic information.

The Proteogenomic Landscape of Curable Prostate Cancer

DNA sequencing has identified recurrent mutations that drive the aggressiveness of prostate cancers. Surprisingly, the influence of genomic, epigenomic, and transcriptomic dysregulation on the tumor proteome remains poorly understood. We profiled the genomes, epigenomes, transcriptomes, and proteomes of 76 localized, intermediate-risk prostate cancers. We discovered that the genomic subtypes of prostate cancer converge on five proteomic subtypes, with distinct clinical trajectories. ETS fusions, the most common alteration in prostate tumors, affect different genes and pathways in the proteome and transcriptome. Globally, mRNA abundance changes explain only ∼10% of protein abundance variability. As a result, prognostic biomarkers combining genomic or epigenomic features with proteomic ones significantly outperform biomarkers comprised of a single data type.

BPG: Seamless, automated and interactive visualization of scientific data

BACKGROUND

We introduce BPG, a framework for generating publication-quality, highly-customizable plots in the R statistical environment.

RESULTS

This open-source package includes multiple methods of displaying high-dimensional datasets and facilitates generation of complex multi-panel figures, making it suitable for complex datasets. A web-based interactive tool allows online figure customization, from which R code can be downloaded for integration with computational pipelines.

CONCLUSION

BPG provides a new approach for linking interactive and scripted data visualization and is available at http://labs.oicr.on.ca/boutros-lab/software/bpg or via CRAN at https://cran.r-project.org/web/packages/BoutrosLab.plotting.general.

Integrated somatic subtypes of localized intermediate-risk prostate cancer

e560

Background: Approximately two thirds of intermediate risk prostate cancer patients are over- or under- treated because we cannot correctly prognose this risk group; therefore we require novel biomarkers to better direct patient therapies and avoid subjecting patients to side effects without benefit. One reason genomic biomarkers are not currently used in clinical settings is because they are notoriously difficult to validate in follow-up studies. Furthermore, the lack of clear prostate cancer subtypes prevents the development of subtype specific biomarkers as is standard practice in breast cancer. We aim to improve biomarker validation rates by defining prostate cancer subtypes that can be used to create subtype specific biomarkers. Methods: First, we assess large scale genomic patterns using whole genome sequencing and methylation data and create integrative subtypes for intermediate risk prostate cancer. Second, we assess associations between specific aberrations and subtypes, and determine whether certain types of molecular aberrations are more important background aberrations for subtype specific biomarker development. Finally, we assess biases in prognostic performance of the published Lalonde biomarker between groups associated with patient subtypes to show that subtype aware biomarkers are necessary. Results: We demonstrate that the Lalonde biomarker is biased by the cohorts’ proportion of TMPRSS2-ERG (T2E) aberrations illustrating the need to develop different biomarkers for patients with T2E and patients without T2E. Further, we suggest integrative subtypes can be used to select patients with similar genomic profiles for biomarker analysis to improve biomarker validation rates. Conclusions: This analysis provides direct guidance for future biomarker development and addresses an important barrier to clinical use of genomic biomarkers for prostate cancer.

VennDiagramWeb: a web application for the generation of highly customizable Venn and Euler diagrams

BACKGROUND

Visualization of data generated by high-throughput, high-dimensionality experiments is rapidly becoming a rate-limiting step in computational biology. There is an ongoing need to quickly develop high-quality visualizations that can be easily customized or incorporated into automated pipelines. This often requires an interface for manual plot modification, rapid cycles of tweaking visualization parameters, and the generation of graphics code. To facilitate this process for the generation of highly-customizable, high-resolution Venn and Euler diagrams, we introduce VennDiagramWeb: a web application for the widely used VennDiagram R package. VennDiagramWeb is hosted at http://venndiagram.res.oicr.on.ca/ .

RESULTS

VennDiagramWeb allows real-time modification of Venn and Euler diagrams, with parameter setting through a web interface and immediate visualization of results. It allows customization of essentially all aspects of figures, but also supports integration into computational pipelines via download of R code. Users can upload data and download figures in a range of formats, and there is exhaustive support documentation.

CONCLUSIONS

VennDiagramWeb allows the easy creation of Venn and Euler diagrams for computational biologists, and indeed many other fields. Its ability to support real-time graphics changes that are linked to downloadable code that can be integrated into automated pipelines will greatly facilitate the improved visualization of complex datasets. For application support please contact Paul.Boutros@oicr.on.ca.

The effect of gestational age and cervical length measurements in the prediction of spontaneous preterm birth in twin pregnancies: an individual patient level meta-analysis

OBJECTIVE

To assess the effect of gestational age (GA) and cervical length (CL) measurements at transvaginal ultrasound (TVUS) in the prediction of preterm birth in twin pregnancy.

DESIGN

Individual patient data (IPD) meta-analysis.

SETTING

International multicentre study.

POPULATION

Asymptomatic twin pregnancy.

METHODS

MEDLINE and EMBASE searches were performed and IPD obtained from authors of relevant studies. Multinomial logistic regression analysis determined probabilities for birth at ≤28(+0) , 28(+1) to 32(+0) , 32(+1) to 36(+0) , and ≥36(+1) weeks as a function of GA at screening and CL measurements.

MAIN OUTCOME MEASURES

Predicted probabilities for preterm birth at ≤28(+0) , 28(+1) to 32(+0) , and 32(+1) to 36(+0) .

RESULTS

A total of 6188 CL measurements were performed on 4409 twin pregnancies in 12 studies. Both GA at screening and CL had a significant and non-linear effect on GA at birth. The best prediction of birth at ≤28(+0) weeks was provided by screening at ≤18(+0) weeks (P < 0.001), whereas the best prediction of birth between 28(+1) and 36(+0) weeks was provided by screening at ≥24(+0) weeks (P < 0.001). Negative prediction value of 100% for birth at ≤28(+0) weeks is achieved at CL 65 mm and 43 mm at ultrasound GA at ≤18(+0) weeks and at 22(+1) to 24(+0) weeks, respectively.

CONCLUSION

In twin pregnancies, prediction of preterm birth depends on both CL and the GA at screening. When CL is <30 mm, screening at ≤18(+0) weeks is most predictive for birth at ≤28(+0) weeks. Later screening at >22(+0) weeks is most predictive of delivery at 28(+1) to 36(+0) weeks. In twins, we recommend CL screening in twins to commence from ≤18(+0) weeks.

TWEETABLE ABSTRACT

An individual patient meta-analysis assessing gestation and CL in the prediction of preterm birth in twins.

Spatial genomic heterogeneity within localized, multifocal prostate cancer

Herein we provide a detailed molecular analysis of the spatial heterogeneity of clinically localized, multifocal prostate cancer to delineate new oncogenes or tumor suppressors. We initially determined the copy number aberration (CNA) profiles of 74 patients with index tumors of Gleason score 7. Of these, 5 patients were subjected to whole-genome sequencing using DNA quantities achievable in diagnostic biopsies, with detailed spatial sampling of 23 distinct tumor regions to assess intraprostatic heterogeneity in focal genomics. Multifocal tumors are highly heterogeneous for single-nucleotide variants (SNVs), CNAs and genomic rearrangements. We identified and validated a new recurrent amplification of MYCL, which is associated with TP53 deletion and unique profiles of DNA damage and transcriptional dysregulation. Moreover, we demonstrate divergent tumor evolution in multifocal cancer and, in some cases, tumors of independent clonal origin. These data represent the first systematic relation of intraprostatic genomic heterogeneity to predicted clinical outcome and inform the development of novel biomarkers that reflect individual prognosis.

Ensemble analyses improve signatures of tumour hypoxia and reveal inter-platform differences

Background

The reproducibility of transcriptomic biomarkers across datasets remains poor, limiting clinical application. We and others have suggested that this is in-part caused by differential error-structure between datasets, and their incomplete removal by pre-processing algorithms.

Methods

To test this hypothesis, we systematically assessed the effects of pre-processing on biomarker classification using 24 different pre-processing methods and 15 distinct signatures of tumour hypoxia in 10 datasets (2,143 patients).

Results

We confirm strong pre-processing effects for all datasets and signatures, and find that these differ between microarray versions. Importantly, exploiting different pre-processing techniques in an ensemble technique improved classification for a majority of signatures.

Conclusions

Assessing biomarkers using an ensemble of pre-processing techniques shows clear value across multiple diseases, datasets and biomarkers. Importantly, ensemble classification improves biomarkers with initially good results but does not result in spuriously improved performance for poor biomarkers. While further research is required, this approach has the potential to become a standard for transcriptomic biomarkers.

Abstract B129: Clinical implications of inter- and intra- prostatic heterogeneity

Men with localized prostate cancer vary widely in clinical outcome, with a 30-50% failure rate after primary treatment. There is thus significant interest in developing genomically refined prognostic groups. We sought to evaluate the extent of genetic heterogeneity, both between patients (inter-prostate) and within individual prostate glands (intra-prostate) to assess the impact of genetic heterogeneity on risk stratification within a tight clinical cohort.

Copy number aberrations (CNAs) from 75 Gleason 7 patients were determined by OncoScan SNP microarrays. We measure the percentage of genome involved in a CNA, termed percent genome aberration (PGA), a proxy for genomic instability. Additionally, whole genome sequencing was applied to 10 intermediate-risk prostate tumours and matched blood, including multiple manually macro-dissected regions from 5 of the prostates (range 2 to 9). Somatic single nucleotide variants (SNVs) and genomic rearrangements (GR) were extracted from each patient.

We find a high degree of inter-prostatic heterogeneity between the 75 Gleason 7 patients, with the number of CNAs per patient ranging from 0 to 929, corresponding to PGA 0 to 16.7%. Known prognostic markers can differentiate between patients at higher risk for biochemical recurrence, but only account for a fraction of the cohort. Notably, when these prognostic genes are examined within multiple regions of five independent tumours, they differ in copy number between cancerous regions of the same prostate. For example, TP53 is deleted in 1/2, 1/3, 4/9, 0/4, and 4/5 prostate regions. Indeed, phylogenetic analysis of geographically distinct regions revealed multi-clonal disease in two of the five patients; separate analyses based on SNVs, CNAs, and GRs all concluded that these patient have two genetically distinct cancers within their prostate.

We demonstrate dramatic levels of inter- and intra- prostate genetic heterogeneity within pathologically identical or similar cancers. The observed intra-prostatic genomic heterogeneity, both in terms of multi-focal and multi-clonal disease, has critical implications for clinical management. Prognostic information obtained by biopsy may be inconsistent depending on the site of biopsy, and applying personalized medicine to prostate cancer will be challenging. This study highlights the need for further evaluation of how intra-prostatic heterogeneity is related to patient prognosis.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B129.

Citation Format: Emilie Lalonde, Paul C. Boutros, Michael Fraser, Richard de Borja, Nicholas J. Harding, Dominique Trudel, Alice Meng, Pablo H. Hennings-Yeomans, Andrew McPherson, Amin Zia, Jianxin Wang, Timothy Beck, Natalie S. Fox, Taryne Chong, Michelle Sam, Jeremy Johns, Lee Timms, Nicholas Buchner, Sohrab Shah, Cenk Sahinalp, Thomas J. Hudson, John D. McPherson, Theodorus van der Kwast, Robert G. Bristow. Clinical implications of inter- and intra- prostatic heterogeneity. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B129.

Abstract 2003: A molecular portrait of potentially curable prostate cancer

Intermediate risk prostate cancer (CaP) with Gleason score (GS) of 7 show up to 100x variability in genetic instability. As CaP is multifocal and likely multiclonal, there is a need to characterize heterogeneity for patient stratification, which would increase the ability to act on genomic information by adding adjuvant therapies to offset systemic occult metastases that currently limit cure in ∼30% of patients. Individual genetic portraits could be used to improve cure on combined clinical-molecular staging criteria.

We undertook a pilot study to assess the genetic heterogeneity of potentially curable GS=7 CaP. We selected 10 men with GS=7 CaP; 5 treated with external beam radiotherapy (frozen pre-treatment biopsies) and 5 treated with radical prostatectomy (RadP, frozen tumour). Additionally, DNA from 18 distinct formalin-fixed, paraffin-embedded (FFPE) foci from the 5 RadP were analysed. Each of these 28 foci were subjected to whole-genome sequencing (WGS) and OncoScan SNP arrays to yield comprehensive genetic profiles. mRNA expression was evaluated on frozen RadP by microarray. Germline DNA from whole-blood was also analysed.

Following independent pathology reviews and manual macro-dissection of tumour areas of ≥70% cellularity, WGS (≥50x tumour, ≥30x germline) was performed on as little as 50 ng genomic DNA, and OncoScan arrays were performed using as little as 30ng DNA using either amplified or innate genomic DNA. Regions of CaP in FFPE RadP were recorded using a tissue map to identify independent malignant foci, and ERG immunostaining was performed to assist in the identification. In cases where ERG-positive and -negative foci were adjacent, ERG staining was repeated on an un-stained slide to confirm separate foci based on 3D multi-section analyses. ERG fusion status was also assessed in frozen samples by aCGH or IHC.

Validation of SNVs via SNP array and deep-resequencing showed ∼99% accuracy. Tumour cellularity was estimated using Qpure and was &gt;60% for all samples. Phylogenetic techniques were used to demonstrate clear multi-clonality in two tumours. Across all tumours, ∼50% of SNVs were specific to an individual tumour-region. Phylogenies were confirmed with both SNVs and CNAs, but CNAs generally exhibited greater concordance amongst different regions of the same tumour. Some previously observed recurrent mutations were previously identified as recurrent in CaP (e.g. SPOP), and the overall mutation rate for intermediate-risk CaP was only somewhat below that reported for castrate-resistant disease (11,230 somatic SNVs per tumour).

Our studies support the concept that a complete characterization of inter- and intra-CaP heterogeneity is possible in fresh and archival tissues; the latter is important for correlations to clinical outcome. These approaches can then be streamlined for high-throughput analyses within personalized medicine laboratories leading to “point of care” molecular tests and individualization of therapy.

Citation Format: Michael E. Fraser, Richard de Borja, Dominique Trudel, Nicholas J. Harding, Pablo H. Hennings-Yeomans, Alice Meng, Emilie R. Lalonde, Andrew Brown, Natalie S. Fox, Taryne Chong, Amin Zia, Michelle Sam, Jianxin Wang, Michelle A. Chan-Seng-Yue, Jeremy Johns, Lee Timms, Nicholas Buchner, Ada Wong, Fouad Yousif, Rob Denroche, Gaetano Zafarana, Maud HW Starmans, Hanbert Chen, Shaylan Govind, Francis Nguyen, Melania Pintilie, Neil Fleshner, Stanislav Volik, Lakshmi Muthuswamy, Colin C. Collins, Thomas J. Hudson, Lincoln D. Stein, Timothy Beck, John D. McPherson, Theodorus van der Kwast, Paul C. Boutros, Rob G. Bristow. A molecular portrait of potentially curable prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2003. doi:10.1158/1538-7445.AM2013-2003

Ovulation induction and small for gestational age neonates in twin pregnancies

OBJECTIVE

To compare the incidence of small for gestation age (SGA) neonates in twin gestations conceived by ovulation induction or in vitro fertilization with that of twins conceived spontaneously.

STUDY DESIGN

A retrospective cohort study was conducted. Subjects were delivered by a single obstetric practice between 2005 and 2011 at the Mount Sinai Medical Center. Maternal and neonatal data were recorded. Our primary outcome was the incidence of SGA, defined as birth weight <10th percentile, from the three modes of conception. Chi square, ANOVA, Fisher's exact test, the Kruskal-Wallis test, the Mantel-Haenszel test, and logistic regression were used in the analysis.

RESULTS

In unadjusted analysis, using the records of 756 infants from 378 mothers of twin pregnancies, twins conceived by ovulation induction had an increased incidence of SGA (28.1%) compared to those conceived spontaneously (17.1%) and by in vitro fertilization (16.5%, p = 0.006). In a logistic regression model accounting for correlated responses between twins and adjusting for gestational age, gender, chorionicity, and maternal age, the odds ratio (95% confidence interval [CI]) of SGA for the ovulation induction group compared to the spontaneous conception group was 2.64 (1.38-5.05, p = 0.003). The odds ratio (95% CI) of SGA for the in vitro fertilization group compared to the spontaneous conception group was 1.51 (0.88-2.61, p = 0.135).

CONCLUSIONS

When adjusted for gestational age, gender, chorionicity, and maternal age, twin neonates conceived by ovulation induction, but not those conceived by in vitro fertilization, had increased odds of SGA compared to those conceived spontaneously.

Cervical length at 30-32 weeks and the risk of Cesarean delivery in twin pregnancies

OBJECTIVES

To estimate the association between the cervical length (CL) measurement at 30-32 weeks and the mode of delivery in twin pregnancies.

METHODS

This was a retrospective study of a cohort, from 2005-2010, of 265 twin pregnancies with a CL measurement at 30-32 weeks. We compared the CL measurement at 30-32 weeks based on mode of delivery. We then analyzed our data across four subgroups, based on the CL measurement quartiles at 30-32 weeks. We performed this analysis in all patients, and also performed a planned subgroup analysis of 130 patients who attempted a vaginal delivery.

RESULTS

In all patients, including those who attempted a vaginal delivery, the mean CL at 30-32 weeks was significantly shorter in women who delivered vaginally compared with women who had a Cesarean section. The likelihood of Cesarean delivery increased significantly with increasing CL measurement across the groups defined by measurement quartiles. On adjusted analysis controlling for maternal age, race, in-vitro fertilization, chorionicity, induction of labor and prior vaginal delivery, the CL measurement at 30-32 weeks was independently associated with mode of delivery.

CONCLUSIONS

In twin pregnancies, the CL at 30-32 weeks is significantly associated with the likelihood of Cesarean delivery. A longer CL may represent underdevelopment of the uterus, leading to a higher risk of Cesarean delivery in labor at term.

Intravaginal misoprostol versus Foley catheter for labour induction: a meta-analysis

BACKGROUND

There are a number of agents used for cervical ripening prior to the induction of labour. Two commonly used agents are intravaginal misoprostol and a transcervical Foley catheter.

OBJECTIVE

To review the evidence comparing misoprostol and transcervical Foley catheter placement for induction of labour, and perform a meta-analysis comparing these two induction agents.

SEARCH STRATEGY

We conducted database searches of PubMed, Embase, the Cochrane Library Database, and the ClinicalTrials.gov website. Bibliographies of all relevant articles were reviewed.

SELECTION CRITERIA

Prospective, randomised trials comparing the use of intravaginal misoprostol and transcervical Foley catheter for the purpose of cervical ripening and induction of labour were included. We excluded studies in which the patients in these two intervention groups also received other induction agents concurrently, such as oral misoprostol, oxytocin, or other prostaglandins.

DATA COLLECTION AND ANALYSIS

The primary outcomes selected were time to delivery, and the rates of caesarean section, uterine tachysystole, and chorioamnionitis. Random-effects generalised linear models with a poisson distribution and log link function were used to compare the two induction agents across the studies.

MAIN RESULTS

Nine studies (1603 patients) were identified as eligible to be included in this meta-analysis. There were no significant differences in the mean time to delivery (mean difference 1.08 ± 2.19 hours shorter for misoprostol, P = 0.2348), the rate of caesarean delivery (RR 0.991; 95% CI 0.768, 1.278), or in the rate of chorioamnionitis (RR 1.130; 95% CI 0.611, 2.089) between women who received misoprostol compared with transcervical Foley catheter. Patients who received misoprostol had significantly higher rates of tachysystole compared with women who received a transcervical Foley catheter (RR 2.844; 95% CI 1.392, 5.812).

CONCLUSIONS

Intravaginal misoprostol and transcervical Foley catheter have similar effectiveness as induction agents. Transcervical Foley catheter is associated with a lower incidence of tachysystole.

Second-trimester fetal growth as a predictor of poor obstetric and neonatal outcome in patients with low first-trimester serum pregnancy-associated plasma protein-A and a euploid fetus

OBJECTIVE

To examine if fetal growth during the second trimester predicts poor pregnancy and neonatal outcome in patients with low first-trimester serum pregnancy-associated plasma protein-A (PAPP-A) and a euploid fetus.

METHODS

We identified all patients with first-trimester PAPP-A<5th centile who had undergone first- and second-trimester ultrasound examination. We excluded multiple pregnancies and those with aneuploidy or major anomalies identified before or after birth. We compared pregnancies with and without ultrasound markers for fetal growth restriction at 18-24 weeks.

RESULTS

We identified 239 patients with low PAPP-A, 25 (10.5%) of whom had evidence of fetal growth restriction at 18-24 weeks. These 25 cases had significantly higher rates of third-trimester small-for-gestational age (SGA) fetus, gestational hypertension, preterm birth, indicated preterm birth, low birth weight and birth weight centiles, 1-min Apgar score<7, neonatal intensive care unit admission and fetal or neonatal death.

CONCLUSION

Among patients with low first-trimester PAPP-A and a euploid fetus, fetal growth in the second trimester can predict poor obstetric and neonatal outcome.

Second-trimester fetal growth and the risk of poor obstetric and neonatal outcomes

OBJECTIVE

To compare outcomes of fetuses with an estimated fetal weight (EFW) < 25(th) percentile in the second trimester to those in fetuses with EFW >or= 25(th) percentile in the second trimester.

METHODS

We compared outcomes of 252 pregnancies with an EFW < 25(th) percentile at 18-24 weeks' gestation with those of 265 controls. All pregnancies had early dating by ultrasonography. We excluded fetuses with aneuploidy, major malformations, second-trimester rupture of membranes, and multiple pregnancies.

RESULTS

Second-trimester EFW < 25(th) percentile was significantly associated with higher rates of fetal or neonatal death, third-trimester small for gestational age (SGA), Doppler abnormalities, indicated preterm birth, gestational hypertension or pre-eclampsia before labor, lower birth weight, birth weight < 10(th) percentile, birth weight < 5(th) percentile, and admission to the neonatal intensive care unit. Many of these associations remained even after excluding patients with oligohydramnios, fetal echogenic bowel, and growth asymmetry.

CONCLUSION

Second-trimester SGA, as defined by an EFW < 25(th) percentile using current growth curves, is associated with poor obstetric and neonatal outcomes. Increased surveillance of such pregnancies may be necessary.

Short cervix: is a follow-up measurement useful?

OBJECTIVE

To study if a repeat cervical length (CL) measurement in the patient already diagnosed with a short cervix has any additional value in the prediction of preterm delivery.

STUDY DESIGN

This was a retrospective study of singleton pregnancies with cervical lengths 1-25 mm at a gestational age of 16-28 weeks seen in our institution between 2002 and 2005. Patients who were managed expectantly and had a follow-up CL measurement within 3 weeks were included. Delivery data were obtained from the patients' computerized medical records.

RESULTS

Sixty-eight patients met the inclusion criteria. 37% of the patients had a shorter CL on the second measurement. These patients delivered at an earlier gestational age (36+4 vs. 38+2 weeks, P=0.031) and were more likely to deliver at <37 weeks (60% vs. 26%, P=0.009). The change in the CL correlated with earlier gestational age at delivery and delivery at <37 weeks.

CONCLUSION

In patients diagnosed with a short cervix, follow-up CL measurement is a strong predictor of preterm delivery. Greater change in the CL correlates with an earlier gestational age at delivery. In the patient diagnosed with a short cervix, a repeat measurement of CL gives additional predictive value.

The cellular repressor of E1A-stimulated genes mediates glucocorticoid-induced loss of the type-2 IGF receptor in ileal epithelial cells

Glucocorticoids induce hypertrophy of the neonatal ileal mucosa but the molecular mechanisms behind this growth induction remain poorly understood. Ileal epithelial cells (IECs) are dependent upon IGF-II for proliferation both in vivo and in culture. The type-2 IGF receptor (IGFR-2) is a lysosomal transport protein that attenuates IGF-II-driven growth and is highly abundant in the ileum. The cellular repressor of E1A-stimulated genes (CREG) is a secreted phosphoglycoprotein that affects cell fate via ligand binding with IGFR-2, although the mechanism by which it does so is unknown. We hypothesized that glucocorticoids might facilitate IGF-mediated hypertrophy through CREG-mediated degradation of IGFR-2. To test this hypothesis, confluent rat IECs (IEC-18) were cultured for 72 h with or without dexamethasone (DEX) and harvested for Western blot, immunocytochemistry, gene array and CREG immunoneutralization experiments. IGFR-2 and CREG immunohistochemistry were also performed in archived ileal specimens from control and DEX-exposed newborn mice and extremely premature infants to investigate in vivo and clinical relevance. DEX exposure was found to diminish IGFR-2 immunolocalization in cultured rat IECs, newborn mouse ileal mucosa and human neonatal ileal mucosa. Gene array data indicated that IGFR-2 expression was unchanged with DEX treatment, suggesting a mechanism of protein degradation. CREG immunolocalization and abundance was found to be increased by DEX and immunoneutralization of CREG resulted in the abolition of IGFR-2 degradation. We have concluded that CREG is a secreted mediator by which DEX induces degradation of IGFR-2 and speculate that this is a fundamental mechanism of mucosal growth induction.