Photovoltaics, plasmonics, plastic antibodies and electrochromism combined for a novel generation of self-powered and self-signalled electrochemical biomimetic sensors.

This work describes further developments into the self-powered and self-signalled biosensing system that merges photovoltaic cells, plastic antibodies and electrochromic cells into a single target. Herein, the plasmonic effect is introduced to improve the photoanode features of the photovoltaic cell, a dye sensitized solar cell (DSSC), and better electrocatalytic features are introduced in the electrode containing the sensing element. In brief, the DSSC had a counter-electrode of poly(3,4-ethylenedioxythiophene) on an FTO glass modified by a plastic antibody of 3,4-ethylenedioxythiophene and pyrrol. The photoanode had dye sensitized TiO2 modified with gold nanoparticles (AuNPs) to increase the cell efficiency, aiming to improve the sensitivity of the response of hybrid device for the target biomarker. The target biomarker was carcinoembryonic antigen (CEA). The response of the hybrid device evidenced a linear trend from 0.1 ng/mL to 10 µg/mL, with an anionic slope of 0.1431 per decade concentration. The response of the plastic antibody for CEA revealed great selectivity against other tumour markers (CA 15-3 or CA 125). The colour response of the electrochromic cell was also CEA concentration dependent and more sensitive when the hybrid device was set-up with a photoanode with AuNPs. A more intense blue colour was obtained when higher concentrations of CEA were present. Overall, this improved version of the self-powered and self-signalled set-up has zero-requirements and is particularly suitable for point-of-care analysis (POC). It is capable of screening CEA in real samples and differentiating clinical levels of interest. This concept opens new horizons into the current cancer screening approaches.

Development of a multiplexed giant magnetoresistive biosensor array prototype to quantify ovarian cancer biomarkers.

In this work, we developed benchtop and handheld Giant Magnetoresistive (GMR) biosensing systems that serve as platforms for detecting a wide variety of protein biomarkers for human diseases. System development included spintronic and nanomagnetic materials, biomolecular chemistry, electronic circuitry, analog and digital signal processing, firmware programming, user interface programming on both PC and Android smartphone, communications over both USB and Bluetooth, and mechanical integration. In this work, we demonstrated the benchtop GMR biosensing system in the context of ovarian cancer assay development. The prototype system delivered the required performance in terms of high-sensitivity multiplex assays in a portable format with enough flexibility to serve as a platform for ovarian cancer and many other diseases. We achieved multiplex detection of cancer antigen 125 (CA125 II), human epididymis protein 4 (HE4), and interleukin 6 (IL6), with limits of detection (LOD) as low as 3.7 U/mL, 7.4 pg/mL, and 7.4 pg/mL, respectively.

Dual-wavebands-resolved electrochemiluminescence multiplexing immunoassay with dichroic mirror assistant photomultiplier-tubes as detectors.

A dual-wavebands-resolved electrochemiluminescence (ECL) multiplexing immunoassay (MIA) was developed for simultaneously detecting alpha fetoprotein antigen (AFP) in greenish waveband with CdSe550 (λmax = 550 nm) nanocrystals (NCs) and carbohydrate antigen 125 (CA125) in near-infrared waveband with CdTe790 (λmax = 790 nm) NCs via one-pot ECL reaction, in which dichroic mirror works as a key part to reflect ECL from CdSe550 to one photomultiplier-tube (PMT) and transmit ECL from CdTe790 to the other PMT for dual-wavebands-resolved assay. The proposed ECL-MIA strategy was capable of simultaneously determining AFP with linearly response from 5 pg/mL to 5 ng/mL and limit of detection at 1 pg/mL, and CA125 with linearly response from 5 mU/mL to 1 U/mL and limit of detection at 1 mU/mL, with desired specificity and without obvious energy-transfer between ECL tags. The dichroic mirror assistant ECL setup is easy-to-assemble and convenient for the popularization of color-resolved multiplexing ECL assay.

Ultrasensitive electrochemiluminescence immunoassay for simultaneous determination of CA125 and CA15-3 tumor markers based on PAMAM-sulfanilic acid-Ru(bpy)32+ and PAMAM-CdTe@CdS nanocomposite.

A multiplex ultrasensitive electrochemiluminescence (ECL) immunoassay was developed for the simultaneous determination of two different tumor markers, cancer antigen 153 (CA 15-3) and cancer antigen 125 (CA 125) using polyamidoamine dendrimer-quantum dots (PAMAM-QDs) and PAMAM-sulfanilic acid-Ru(bpy)32+ as the signal probes and Fe3O4-SiO2 as a magnetic bead. The CdTe@CdS- QDs and Ru(bpy)32+ at the presence of tripropyl amine (TPA) as coreactant generate ECL at an applied voltage of + 1.2V (vs Ag/AgCl) in two different wavelengths 500 and 620nm, respectively. Based on this strategy, the simultaneous detection of two tumor markers in single run carried out. This dual signal amplification technique was achieved by employing Fe3O4@SiO2-dendrimer as immunosensing platform and PAMAM as the carrier for immobilizing CdTe@CdS and Ru(bpy)32+ probes. Experimental results illustrated that the designed immunosensor can be used to sequentially detection of CA 125 and CA 15-3 markers with the wide linear ranges of 1µU/mL to 1U/mL and 0.1mU/mL to 100U/mL with very low detection limits of 0.1µU/mL and 10µU/mL, respectively. The application of the immunosensor for simultaneous detection of CA125 and CA15-3 in human serum samples was evaluated and the obtained results were found to be in acceptable agreement with the those obtained with an ELISA assay as reference method. The proposed ECL immunosensor can provide a simple, sensitive and reliable approach for the simultaneous detection of tumor markers in clinical samples.

Potential-resolved "in-electrode" type electrochemiluminescence immunoassay based on functionalized g-C3N4 nanosheet and Ru-NH2 for simultaneous determination of dual targets.

Here, a novel potential-resolved "in-electrode" type electrochemiluminescence (ECL) immunosensor was fabricated based on two different types of luminant Ru-NH2 and AuNPs/g-C3N4 to realize simultaneous detection of dual targets. In this strategy, anti-CA1251 and anti-SCCA1 were immobilized on bare gold electrode as capture probes, which could catch the two corresponding target CA125 and SCCA, and the immobilization of the signal tags was allowed via the interaction between antigen and antibody. In this process, (Ru&anti-CA1252)@GO and anti-SCCA2-AuNPs/g-C3N4 could exhibit two strong and stable ECL emissions at 1.25V and -1.3V respectively, which could be used as effective signal tags. Taking advantage of "in-electrode" type ECL immunosensor, all the electrochemiluminophores near the outer Helmholtz plane are "effective" in participating in the electrochemical reactions and emitting ECL signals. Therefore, the dual targets CA125 and SCCA could be detected within the linear ranges of 0.001-100U/mL and 0.001-100ng/mL, with detection limits of 0.4mU/mL and 0.33pg/mL, respectively. All these results demonstrated that the present potential-resolved "in-electrode" type electrochemiluminescence approach provided a promising analytical method for dual targets analysis with the advantages of simple analytical procedure, small sample volume and lower cost, which made the proposed method potential for clinical detection.

A reusable electrochemical immunosensor fabricated using a temperature-responsive polymer for cancer biomarker proteins.

In the present study, we describe a reusable electrochemical immunosensor for the repeated detection of cancer biomarkers using a single platform. The integration of a temperature-responsive polymer on the electrode surface enables easy manipulation of the biological sensing interface (i.e., addition of biotin, streptavidin, and antibody), thus allowing for temperature-induced regeneration and disruption of the interface architecture of the electrode surface. Using our immunosensor, we demonstrate sequential amperometric detection of three tumor markers: CA125, CEA, and PSA. Interestingly, greatly amplified signals are achieved by immersing the immunosensor in a solution of horseradish peroxidase (HRP) and antibody-labeled nanoparticles, resulting in a linear range of 0.0064 to 256 U/mL, 1 pg/mL to 100 ng/mL, and 10 pg/mL to 10 ng/mL with a detection limit of 0.007 U/mL, 0.7 pg/mL, and 0.9 pg/mL for CA125, CEA, and PSA, respectively. By alternating temperature, the immunosensor adsorbs and desorbs the biological elements without damage. Our proposed methodology can be expanded to measure other relevant biological species by repeated detection and thus has enormous potential for industrial and clinical applications.

Immobilization strategy for enhancing sensitivity of immunosensors: L-Asparagine-AuNPs as a promising alternative of EDC-NHS activated citrate-AuNPs for antibody immobilization.

This paper addresses the question - Is EDC-NHS activated gold nanoparticles modified electrode surface the best available option for antibody immobilization for immunosensor fabrication? Is there any other alternative covalent immobilization strategy for orthogonal orientation of antibody, ensuring enhanced sensitivity of immunosensors? Does EDC-NHS activation of carboxyl functionalized nanoparticles surface really leads to orthogonal or directed immobilization of antibody? Gold nanoparticles synthesized using L-Asparagine as reducing and stabilization agent were employed for orthogonal immobilization of antibody for immunosensor fabrication. Anti-CA125 antibody was used as a model system for immunosensor fabrication. A comparative evaluation of immunosensors fabricated using L-Asparagine stabilized gold nanoparticles and citrate stabilized gold nanoparticles via different immobilization strategies/chemistries was done. The three strategies involved immobilization of Anti-CA125 antibody - (1) after EDC-NHS activation of citrate stabilized gold nanoparticles, (2) directly onto citrate stabilized gold nanoparticles and (3) directly onto L-Asparagine stabilized gold nanoparticles modified electrode surfaces. Comparative evaluation of Impedimetric response characteristics showed 2.5 times increase in sensitivity (349.36 Ω/(IU/mL)/cm(2)) in case of third strategy as compared to first (147.53 Ω/(IU/mL)/cm(2)) and twice that of second strategy (166.24 Ω/(IU/mL)/cm(2)). Additionally, an extended dynamic range of 0-750 IU/mL was observed while for others it was up to 500 IU/mL. Amino acid coated gold nanoparticles ensured orthogonal immobilization, lesser randomization, with 88% of active antibody available for antigen binding as opposed to other two strategies with less than 30% active antibody.

Ultrasensitive simultaneous detection of four biomarkers based on hybridization chain reaction and biotin-streptavidin signal amplification strategy.

A sandwich-type electrochemical immunosensor based on redox probe tags identification technology for ultrasensitive simultaneous detection of four antigens was proposed. In this project, well-distributed graphene/gold (GR-Au) hybrid film was acquired through one-step codeposition in an electrode surface and served as the base substrate for immobilizing capture antibodies (Ab1). Hybridization chain reaction (HCR) and biotin/streptavidin (B/SA), combining with gold magnetic nanoparticles were applied to increase the immobilization amount of signal tags in detection antibody (Ab2) bioconjugates. To verify this strategy, four representative biomarkers, a-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (CA)125 and prostate special antigen (PSA), were used as model analytes. The resulting immunosensor could simultaneously detect four antigens in single-pass differential pulse voltammetry (DPV) scan, and exhibited obviously improved senstivity compared to previous similar immunosensors, displayed good linear relationships in the ranges from 0.2 to 800 pg/mL for AFP, 0.2 to 600 pg/mL for CEA, 0.2 to 1000 pg/mL for CA125, 0.2 to 800 pg/mL for PSA and with detection limits of 62, 48, 77 and 60 fg/mL, respectively.

3D origami electrochemical immunodevice for sensitive point-of-care testing based on dual-signal amplification strategy.

A dual signal amplification immunosensing strategy that offers high sensitivity and specificity for the detection of low-abundance biomarkers was designed on a 3D origami electrochemical device. High sensitivity was achieved by using novel Au nanorods modified paper working electrode (AuNRs-PWE) as sensor platform and metal ion-coated Au/bovine serum albumin (Au/BSA) nanospheres as tracing tags. High specificity was further obtained by the simultaneous measurement of two cancer markers on AuNRs-PWE surface using different metal ion-coated Au/BSA tracers. The metal ions could be detected directly through differential pulse voltammetry (DPV) without metal preconcentration, and the distinct voltammetric peaks had a close relationship with each sandwich-type immunoreaction. The position and size of the peaks reflected the identity and level of the corresponding antigen. Integrating the dual-signal amplification strategy, a novel 3D origami electrochemical immunodevice for simultaneous detecting carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125) with linear ranges of over 4 orders of magnitude with detection limits down to 0.08 pg mL(-1) and 0.06 mU mL(-1) was successfully developed. This strategy exhibits high sensitivity and specificity with excellent performance in real human serum assay. The AuNRs-PWE and the designed tracer on this immunodevice provided a new platform for low-cost, high-throughput and multiplex immunoassay and point-of-care testing in remote regions, developing or developed countries.

CA-125 of fetal origin can act as a ligand for dendritic cell-specific ICAM-3-grabbing non-integrin.

CA-125 (coelomic epithelium-related antigen) forms the extracellular portion of transmembrane mucin 16 (MUC16). It is shed after proteolytic degradation. Due to structural heterogeneity, CA-125 ligand capacity and biological roles are not yet understood. In this study, we assessed CA-125 as a ligand for dendritic cell-specific ICAM-3-grabbing non-integrin (DC-SIGN), which is a C-type lectin showing specificity for mannosylated and fucosylated structures. It plays a role as a pattern recognition molecule for viral and bacterial glycans or as an adhesion receptor. We probed a human DC-SIGN-Fc chimera with CA-125 of fetal or cancer origin using solid- or fluid-phase binding and inhibition assays. The results showed that DC-SIGN binds to CA-125 of fetal origin and that this interaction is carbohydrate-dependent. By contrast, cancer-derived CA-125 displayed negligible binding. Inhibition assays indicated differences in the potency of CA-125 to interfere with DC-SIGN binding to pathogen-related glycoconjugates, such as mannan and Helicobacter pylori antigens. The differences in ligand properties between CA-125 of fetal and cancer origin may be due to specificities of glycosylation. This might influence various functions of dendritic cells based on their subset diversity and maturation-related functional capacity.

Label-free detection of ovarian cancer biomarkers using whispering gallery mode imaging.

Small optical microresonators that support whispering gallery mode (WGM) resonances are emerging as powerful new platforms for biosensing. These resonators respond to changes in refractive index and potentially offer many advantages for label-free sensing. Recently we reported an approach for detecting WGM resonances based on fluorescence imaging and demonstrated its utility by quantifying the ovarian cancer marker CA-125 in buffer. Here we extend those measurements by reporting a simplified approach for launching WGM resonances using excitation light coupled into a Dove prism. The enhanced phase matching enables significant improvements in signal-to-noise, revealing the mode structure present in each resonator. As with all label-free biosensing techniques, non-specific interactions can be limiting. Here we show that standard blocking protocols reduce non-specific interactions sufficiently to enable CA-125 quantification in serum samples. Finally, fluorescence imaging of WGM resonances offers the potential for large scale multiplexed detection which is demonstrated here by simultaneously exciting and imaging over 120 microsphere resonators. For multiplexed applications, analyte identity can be encoded in the resonator size and/or location. By encoding analyte identity into microresonator size, we simultaneously quantify the putative ovarian cancer markers osteopontin (38 µm diameter sphere), CA-125 (53 µm diameter sphere), and prolactin (63 µm diameter sphere) in a single PBS assay. Together, these results show that fluorescence imaging of WGM resonances offers a promising new approach for the highly multiplexed detection of biomarkers in complex biological fluids.

[Expression and purification of mucin 16 and preparation and characterization of anti-mucin 16 monoclonal antibody].

AIM: To generate monoclonal antibodies (mAbs) against mucin 16 using purified recombinant protein of human mucin 16 N terminus with His tag (His-mucin 16N) as the antigen. METHODS: Mucin 16 N terminus was cloned into a prokaryotic expression vector pET-32. His-mucin 16N was then expressed in E.coli and purified by the affinity chromotography. Cell fusion was performed after the BALB/c mice were immunized with the purified His-mucin 16N protein. We screened hybridoma cell strains producing mAbs against mucin 16. The specificity and titer of the antibodies were characterized with ELISA, Western blotting, immunofluorescent and immunohistochemical staining. RESULTS: The recombinant protein of His-mucin 16N was expressed and purified. A few hybridoma cell strains which could secrete specific mAbs against mucin 16 were obtained, and one anti-mucin 16 mAb with good specificity and high titer was selected and purified. The isotype of this anti-mucin 16 mAb was determined as IgG1, which indicated that this anti-mucin 16 mAb could be used for ELISA, Western blotting, immunofluorescent and immunohistochemical staining. The endogenous expression of mucin 16 in various cancer cell lines or tissues was also examined with this anti-mucin 16 antibody by Western blotting and other immunoassays. CONCLUSION: The recombinant protein of His-mucin 16N was expressed and purified successfully, with which we prepared anti-mucin 16 mAb with good specificity and high titer.

Mucin 16 is a functional selectin ligand on pancreatic cancer cells.

Selectins promote metastasis by mediating specific interactions between selectin ligands on tumor cells and selectin-expressing host cells in the microvasculature. Using affinity chromatography in conjunction with tandem mass spectrometry and bioinformatics tools, we identified mucin 16 (MUC16) as a novel selectin ligand expressed by metastatic pancreatic cancer cells. While up-regulated in many pancreatic cancers, the biological function of sialofucosylated MUC16 has yet to be fully elucidated. To address this, we employed blot rolling and cell-free flow-based adhesion assays using MUC16 immunopurified from pancreatic cancer cells and found that it efficiently binds E- and L- but not P-selectin. The selectin-binding determinants are sialofucosylated structures displayed on O- and N-linked glycans. Silencing MUC16 expression by RNAi markedly reduces pancreatic cancer cell binding to E- and L-selectin under flow. These findings provide a novel integrated perspective on the enhanced metastatic potential associated with MUC16 overexpression and the role of selectins in metastasis.

Expression and epitope characterization of a recombinant CA 125 repeat: fourth report from the ISOBM TD-1 workshop.

BACKGROUND: CA 125 antigenic domains appear to reside within a region containing 156-amino acid sequence repeats. Surprisingly, anti-CA 125 antibodies can be classified into three families (groups A, B and C) indicating limited epitope diversity. In this study we describe the heterologous expression of a CA 125 repeat unit (R11) and an analysis of its epitope topography. METHODS: R11 was expressed using a baculovirus approach and purified from culture supernatants by sequential ion exchange chromatography. Monoclonal antibody binding was assessed using antigen capture and cross-inhibition methods. RESULTS: The recombinant repeat was purified to 2.5 x 10(7) U/mg. Although a number of group A and B monoclonal antibodies were found to bind R11, the prototype antibody OC125 (group A) showed little reactivity. However, the prior binding of some group B monoclonal antibodies dramatically enhanced subsequent OC125 binding. Low monoclonal antibody reactivity to R11 correlated well with poor binding to SDS-denatured human ascites CA 125. CONCLUSION: The ability to 'activate' R11 epitopes indicates that some may not be displayed optimally on isolated repeats. This observation, together with the concordance between monoclonal antibody binding to R11 and denatured CA 125, suggests that a number of epitopes are preferentially displayed only when contained within multiple repeat domains.

Complement-inhibiting effect of ovarian cancer antigen CA-125.

Malignant transformation of ovarian cells of surface epithelial origin is associated with expression of a membrane-spanning glycoprotein, cancer antigen (CA)-125. The bulk of the putative CA-125 molecule is comprised a very large, folded, multivalent, mucin-like exodomain. That the extracellular motif of CA-125 exerts immunosuppressive effects which promote tumor progression has been suggested. We report that CA-125 attenuates complement lysis of antibody-sensitized cells. The secreted form of CA-125 derived from culture medium of the human ovarian adenocarcinoma cell line OVCAR-3 caused a dose-response inhibition of sheep erythrocyte hemolysis. Moreover, OVCAR-3 cells became prone to complement attack (trypan blue uptake) mediated by a gonadotropin-releasing hormone receptor antibody when (membrane-bound) CA-125 was excised/removed by trypsin/washing; this effect was counteracted by replacement with (soluble) CA-125. It is conceivable that CA-125 entraps/sheds effectors of the complement cascade.

Potent suppression of natural killer cell response mediated by the ovarian tumor marker CA125.

OBJECTIVES: CA125 expresses specific oligosaccharides that can inhibit the cytotoxicity of human natural killer (NK) cells. The current study was undertaken to determine the ability of CA125 to modulate NK cell-mediated cytotoxicity. METHODS: CA125 was isolated from OVCAR-3 cells and its purity was determined by ELISA and ultra-sensitive mass spectrometric analysis. Peripheral blood-derived NK were treated with CA125 and standard cytotoxicity assays were performed using 51Cr-labeled K562 cells as targets. The expression of cell surface and intracellular markers on NK cells was determined by either flow cytometry or Western blot analysis. RESULTS: NK cells incubated with CA125 for 72 h exhibited a 50-70% decrease in the lysis of K562 targets. Incubation with CA125 for 4 h and 24 h had no effect on NK-mediated cytolysis. Inhibition of NK function was observed at CA125 concentrations (10,000-100,000 U/ml) that are expected to be significantly lower than those observed in the tumor microenvironment. Co-stimulation with IL-2 did not abrogate the NK inhibitory response of CA125. CA125 did not reduce proliferation or induce apoptosis of NK cells and alter the expression of p56lck, phospholipase Cgamma1, ZAP70, or CD3zeta. CA125 did, however, induce major downregulation of CD16 and minor decrease in expression of CD94/NKG2A. CONCLUSIONS: Our ongoing research and recent work performed by other laboratories highlights the potential physiologic role of this mucin. Based on the data presented here, it is likely that the tumor-derived CA125 acts as a suppressor of the immune response that is directed against the ovarian tumors.

Screening postmenopausal women for ovarian cancer: a systematic review.

OBJECTIVES: To assess ovarian cancer screening in asymptomatic, general-risk postmenopausal women. Outcomes of interest were the screening tests assessed (predictive values, sensitivity, and specificity), the stage of screen-detected disease at diagnosis, psychological effects of screening, and survival. METHODS: MEDLINE, CANCERLIT, and the Cochrane Library databases were searched to June 2003 using the terms "ovarian," "cancer," "neoplasms," "screening," "clinical trial," "meta-analysis," and "systematic review." Studies were included if they were clinical trials, meta-analyses, or systematic reviews that evaluated tests used to detect ovarian cancer in asymptomatic women in the general population. Studies investigating women at increased risk for ovarian cancer (e.g., family history) and those with symptoms suggestive of ovarian cancer were excluded. TABULATION, INTEGRATION, AND RESULTS: Seventeen prospective cohort studies and 3 pilot randomized controlled trials were included in this review. Screening tests for cancer antigen 125 (CA125) and ultrasound had low positive predictive values, resulting in healthy women being recalled and a false-positive rate of 0.01% to 5.8%. Of every 10,000 women participating in an annual screening program with CA125 for 3 years, 800 will have an ultrasound scan because of an elevated CA125, 30 will undergo surgery because of an abnormal ultrasound, and 6 will have ovarian cancer detected at surgery (3 will be diagnosed at early-stage disease and have a chance of a cure). CONCLUSION: There is insufficient evidence to support the introduction of screening for ovarian cancer in the asymptomatic general-risk postmenopausal population. Screening is associated with increased rates of surgery and patient anxiety.

Ovarian cancer screening and prevention.

OBJECTIVES: To review current ovarian cancer prevention and detection recommendations using a risk assessment framework, and discuss the genes related to hereditary ovarian cancer syndromes. DATA SOURCES: Published articles, consensus opinions, and reports. CONCLUSIONS: Women at highest risk are those with a family history and/or genetic predisposition. Management guidelines include pelvic exam, CA125, and transvaginal ultrasound, although their efficacy is limited. Individualized risk assessment can be useful in assisting women who face decisions regarding prevention options. IMPLICATIONS FOR NURSING PRACTICE: Nurses are challenged to identify women at increased risk for ovarian cancer, and to recognize the complex issues faced when these women pursue screening and prevention strategies.

The performance of screening tests for ovarian cancer: results of a systematic review.

OBJECTIVE: To estimate the performance of currently available tests in detecting ovarian cancer in asymptomatic women. METHODS: Systematic review of prospective screening studies. RESULTS: Twenty-five studies were identified: sixteen studied women at average risk and nine studied women at higher risk. Most studies evaluated only one screening method, were small, detecting few cancers, and gave few follow up details. Sensitivity estimates are therefore imprecise. In a typical larger study, reported sensitivity of ultrasound screening at one year was around 100% (95% CI 54%-100%), while the sensitivity of CA125 measurement followed by ultrasound (multimodal screening) was about 80% (95% CI 49%-95%). False positive rates ranged between 1.2% and 2.5% for grey scale ultrasound, between 0.3% and 0.7% for ultrasound with colour Doppler and between 0.1% and 0.6% for multimodal screening. This implies that, in annual screening of a population with an incidence of 40 per 100,000, and if no cancers were missed, between 2.5 and 60 women would undergo surgery for every primary ovarian cancer detected. CONCLUSIONS: Ultrasound and multimodal screening can detect ovarian cancer in asymptomatic women, but there is currently no evidence on whether screening improves outcome for women in any risk group. On-going randomised controlled trials should establish the magnitude of any benefit of screening. The low prevalence of ovarian cancer in the population, and its rate of progression, may limit the potential cost-effectiveness of screening.