Is radiomic MRI a feasible alternative to OncotypeDX® recurrence score testing? A systematic review and meta-analysis

BACKGROUND

OncotypeDX® recurrence score (RS) aids therapeutic decision-making in oestrogen-receptor-positive (ER+) breast cancer. Radiomics is an evolving field that aims to examine the relationship between radiological features and the underlying genomic landscape of disease processes. The aim of this study was to perform a systematic review of current evidence evaluating the comparability of radiomics and RS.

METHODS

A systematic review was performed as per PRISMA guidelines. Studies comparing radiomic MRI tumour analyses and RS were identified. Sensitivity, specificity and area under curve (AUC) delineating low risk (RS less than 18) versus intermediate-high risk (equal to or greater than 18) and low-intermediate risk (RS less than 30) and high risk (RS greater than 30) were recorded. Log rate ratios (lnRR) and standard error were determined from AUC and 95 per cent confidence intervals.

RESULTS

Nine studies including 1216 patients met inclusion criteria; the mean age at diagnosis was 52.9 years. Mean RS was 16 (range 0-75); 401 patients with RS less than 18, 287 patients with RS 18-30 and 100 patients with RS greater than 30. Radiomic analysis and RS were comparable for differentiating RS less than 18 versus RS 18 or greater (RR 0.93 (95 per cent c.i. 0.85 to 1.01); P = 0.010, heterogeneity (I2)=0%) as well as RS less than 30 versus RS 30 or greater (RR 0.76 (95 per cent c.i. 0.70 to 0.83); P < 0.001, I2=0%). MRI sensitivity and specificity for RS less than 18 versus 18 or greater was 0.89 (95 per cent c.i. 0.85 to 0.93) and 0.72 (95 per cent c.i. 0.66 to 0.78) respectively, and 0.79 (95 per cent c.i. 0.72 to 0.86) and 0.74 (95 per cent c.i. 0.68 to 0.80) for RS less than 30 versus 30 or greater.

CONCLUSION

Radiomic tumour analysis is comparable to RS in differentiating patients into clinically relevant subgroups. For patients requiring MRI, radiomics may complement and enhance RS for prognostication and therapeutic decision making in ER+ breast cancer.

Optimal reconstructive strategies in the setting of post-mastectomy radiotherapy - A systematic review and network meta-analysis

BACKGROUND

A third of breast cancer patients require mastectomy. In some high-risk cases postmastectomy radiotherapy (PMRT) is indicated, threatening reconstructive complications. Several PMRT and reconstruction combinations are used. Autologous flap (AF) reconstruction may be immediate (AF→PMRT), delayed-immediate with tissue expander (TE [TE→PMRT→AF]) or delayed (PMRT→AF). Implant-based breast reconstruction (IBBR) includes immediate TE followed by PMRT and conversion to permanent implant (PI [TE→PMRT→PI]), delayed TE insertion (PMRT→TE→PI), and prosthetic implant conversion prior to PMRT (TE→PI→PMRT).

AIM

Perform a network metanalysis (NMA) assessing optimal sequencing of PMRT and reconstructive type.

METHODS

A systematic review and NMA was performed according to PRISMA-NMA guidelines. NMA was conducted using R packages netmeta and Shiny.

RESULTS

16 studies from 4182 identified, involving 2322 reconstructions over three decades, met predefined inclusion criteria. Studies demonstrated moderate heterogeneity. Multiple comparisons combining direct and indirect evidence established AF-PMRT as the optimal approach to avoid reconstructive failure, compared with IBBR strategies (versus PMRT→TE→PI; OR [odds ratio] 0.10, CrI [95% credible interval] 0.02 to 0.55; versus TE→PMRT→PI; OR 0.13, CrI 0.02 to 0.75; versus TE→PI→PMRT OR 0.24, CrI 0.05 to 1.05). PMRT→AF best avoided infection, demonstrating significant improvement versus PMRT→TE→PI alone (OR 0.12, CrI 0.02 to 0.88). Subgroup analysis of IBBR found TE→PI→PMRT reduced failure rates (OR 0.35, CrI 0.15-0.81) compared to other IBBR strategies but increased capsular contracture.

CONCLUSION

Immediate AF reconstruction is associated with reduced failure in the setting of PMRT. However, optimal reconstructive strategy depends on patient, surgeon and institutional factors. If IBBR is chosen, complication rates decrease if performed prior to PMRT.

PROSPERO REGISTRATION

CRD 42020157077.

The impact of progesterone receptor negativity on oncological outcomes in oestrogen-receptor-positive breast cancer

Background

Oestrogen receptor (ER) status provides invaluable prognostic and therapeutic information in breast cancer (BC). When clinical decision making is driven by ER status, the value of progesterone receptor (PgR) status is less certain. The aim of this study was to describe clinicopathological features of ER-positive (ER+)/PgR-negative (PgR-) BC and to determine the effect of PgR negativity in ER+ disease.

Methods

Consecutive female patients with ER+ BC from a single institution were included. Factors associated with PgR- disease were assessed using binary logistic regression. Oncological outcome was assessed using Kaplan–Meier and Cox regression analysis.

Results

In total, 2660 patients were included with a mean(s.d.) age of 59.6(13.3) years (range 21–99 years). Median follow-up was 97.2 months (range 3.0–181.2). Some 2208 cases were PgR+ (83.0 per cent) and 452 were PgR- (17.0 per cent). Being postmenopausal (odds ratio (OR) 1.66, 95 per cent c.i. 1.25 to 2.20, P < 0.001), presenting with symptoms (OR 1.71, 95 per cent c.i. 1.30 to 2.25, P < 0.001), ductal subtype (OR 1.51, 95 per cent c.i. 1.17 to 1.97, P = 0.002) and grade 3 tumours (OR 2.20, 95 per cent c.i. 1.68 to 2.87, P < 0.001) were all associated with PgR negativity. In those receiving neoadjuvant chemotherapy (308 patients), pathological complete response rates were 10.1 per cent (25 of 247 patients) in patients with PgR+ disease versus 18.0 per cent in PgR- disease (11 of 61) (P = 0.050). PgR negativity independently predicted worse disease-free (hazard ratio (HR) 1.632, 95 per cent c.i. 1.209 to 2.204, P = 0.001) and overall survival (HR 1.774, 95 per cent c.i. 1.324 to 2.375, P < 0.001), as well as worse overall survival in ER+/HER2- disease (P = 0.004).

Conclusions

In ER+ disease, PgR- tumours have more aggressive clinicopathological features and worse oncological outcomes. Neoadjuvant and adjuvant therapeutic strategies should be tailored according to PgR status.

Clinical utility of the 21-gene assay in predicting response to neoadjuvant endocrine therapy in breast cancer: A systematic review and meta-analysis

INTRODUCTION

OncotypeDX© Recurrence Score (RS) is a multigene panel used to aid therapeutic decision making in early-stage, estrogen receptor positive (ER+)/human epidermal growth factor receptor-2 negative (HER2-) breast cancer.

AIM

To compare responses to neoadjuvant endocrine therapy (NET) in patients with ER+/HER2-breast cancer following substratification by RS testing.

METHODS

This systematic review was performed in accordance to the PRISMA guidelines. Studies evaluating pathological complete response (pCR), partial response (PR), and successful conversion to breast conservation surgery (BCS) rates following NET guided by RS were retrieved. Dichotomous outcomes were reported as odds ratios (ORs) with 95% confidence intervals (CIs) following estimation by Mantel-Haenszel method.

RESULTS

Eight prospective studies involving 691 patients were included. The mean age was 62.6 years (range 25-85) and the mean RS was 14.5 (range 0-68). Patients with RS < 25 (OR: 4.60, 95% CI: 2.53-8.37, P < 0.001) and RS < 30 (OR: 3.40, 95% CI: 1.96-5.91, P < 0.001) were more likely to achieve PR than their counterparts. NET prescription failed to increase BCS conversion rates for patients with RS < 18 (OR: 0.23, 95% CI: 0.04-1.47, P = 0.120) and RS > 30 (OR: 1.27, 95% CI: 0.64-2.49, P = 0.490) respectively. Only 22 patients achieved pCR (2.8%) and RS group failed to predict pCR following NET (P = 0.850).

CONCLUSION

Estimations from this analysis indicate that those with low-intermediate RS on core biopsy are four times more likely to respond to NET than those with high-risk RS. Performing RS testing on diagnostic biopsy may be useful in guiding NET prescription.

Clinicopathological and prognostic significance of programmed cell death ligand 1 expression in patients diagnosed with breast cancer: meta-analysis

BACKGROUND

Uncertainty exists regarding the clinical relevance of programmed cell death ligand 1 (PD-L1) expression in breast cancer.

METHODS

A systematic review was performed in accordance with PRISMA guidelines. Observational studies that compared high versus low expression of PD-L1 on breast cancer cells were identified. Log hazard ratios (HRs) for disease-free and overall survival and their standard errors were calculated from Kaplan-Meier curves or Cox regression analyses, and pooled using the inverse-variance method. Dichotomous variables were pooled as odds ratios (ORs) using the Mantel-Haenszel method.

RESULTS

Sixty-five studies with 19 870 patients were included; 14 404 patients were classified as having low and 4975 high PD-L1 expression. High PD-L1 was associated with achieving a pathological complete response following neoadjuvant chemotherapy (OR 3.30, 95 per cent confidence interval 1.19 to 9.16; P < 0.01; I2 = 85 per cent). Low PD-L1 expression was associated with human epidermal growth factor receptor 2 (OR 3.98, 1.81 to 8.75; P < 0.001; I2 = 96 per cent) and luminal (OR 14.93, 6.46 to 34.51; P < 0.001; I2 = 99 per cent) breast cancer subtypes. Those with low PD-L1 had favourable overall survival rates (HR 1.30, 1.05 to 1.61; P = 0.02; I2 = 85 per cent).

CONCLUSION

Breast cancers with high PD-L1 expression are associated with aggressive clinicopathological and immunohistochemical characteristics and are more likely to achieve a pathological complete response following neoadjuvant chemotherapy. These breast cancers are, however, associated with worse overall survival outcomes.

O49: EFFECT OF AFIMOXIFENE (Z-4-HYDROXYTAMOXIFEN) ON ADIPOSE-DERIVED STEM CELLS

Background

Adipose-derived stem cells (ADSCs) are a promising cell source for adipose tissue engineering. Currently, novel breast reconstruction techniques using ADSCs are actively being explored. Systemic chemo- & hormonal therapy may impede tissue regeneration in breast cancer patients. However, the effect of hormonal therapy on ADSCs and their regenerative capabilities is poorly understood.

Aims

The current study aims to analyse the effect of Afimoxifene, an active metabolite of Tamoxifen, on proliferation and viability of ADSCs in vitro

Method

Lipoaspirates or adipose tissue were obtained with informed consent from breast cancer patients and healthy controls. The isolated ADSCs were subjected to single or multiple dose(s) of Z-4-Hydroxytamoxifen (12.5nM, 25nM, 50nM, 100nM and 1μM) and, analyzed on days 1, 3 and 5, using CellTitre 96 ® AQueous Cell proliferation assay. T47D and MDA-MB-231 cell lines were used as positive and negative controls, respectively.

Result

ADSCs were obtained from a total of 3 patients. ADSCs were isolated from a cancer patient with/without active disease at the time of sample procurement and healthy subjects opting for elective cosmetic procedures. Morphology, CFU assay and adipogenic differentiation assay were used to validate stem cell population. Afimoxifene demonstrated no statistically significant reduction in the viability or proliferation of the ADSCs, irrespective of the dose- or time-dependent exposure or cancer status (p &gt;0.05).

Conclusion

Afimoxifene has no deleterious effect on viability or proliferation of human ADSCs up to 1μM concentration.

Key words

Adipose-derived stem cells, Afimoxifene, Breast reconstruction, Hormone therapy, Tamoxifen.

Take-home message

Afimoxifene has no deleterious effect on viability or proliferation of human ADSCs up to 1μM concentration

Combined breast conservation therapy versus mastectomy for BRCA mutation carriers - A systematic review and meta-analysis

BACKGROUND

The non-inferiority of combined breast conservation surgery (BCS) and radiotherapy (breast conservation therapy or BCT) compared to mastectomy in sporadic breast cancer cases is well recognised. Uncertainty remains regarding optimal surgical practice in BRCA mutation carriers.

AIMS

To evaluate the oncological safety of combined BCT versus mastectomy in BRCA mutation carriers following breast cancer diagnosis.

METHODS

A systematic review was performed as per PRISMA and MOOSE guidelines. Observational studies comparing BCS and mastectomy in BRCA carriers were identified. Dichotomous variables were pooled as odds ratios (OR) using the Mantel-Haenszel method. Log hazard ratios (lnHR) for locoregional recurrence (LRR), contralateral breast cancer, disease-free and overall survival and their standard errors were calculated from Kaplan-Meier or cox-regression analyses and pooled using the inverse variance method.

RESULTS

Twenty three studies of 3807 patients met inclusion criteria; 2200 (57.7%) were BRCA1 and 1212 (31.8%) were BRCA2 carriers. Median age at diagnosis was 41 years with 96 months follow up. BCS was performed on 2157 (56.7%) while 1408 (41.5%) underwent mastectomy. An increased risk of LRR was observed in patients treated with BCS (HR:4.54, 95% Confidence Interval: 2.77-7.42, P < 0.001, heterogeneity (I2) = 0%). However, the risks of contralateral breast cancer (HR:1.51, 95%CI: 0.44-5.11, P = 0.510, I2 = 80%), disease recurrence (HR:1.16, 95%CI: 0.78-1.72, P = 0.470, I2 = 44%), disease-specific recurrence (HR:1.58, 95%CI: 0.79-3.15, P = 0.200, I2 = 38%) and death (HR:1.10, 95%CI: 0.72-1.69, P = 0.660, I2 = 38%) were equivalent for combined BCT and mastectomy.

CONCLUSIONS

Survival outcomes following combined BCT is comparable to mastectomy in BRCA carriers. However, the risk of LRR is increased. Patient counselling should be tailored to incorporate these findings.

Disease recurrence and oncological outcome of patients treated surgically with curative intent for estrogen receptor positive, lymph node negative breast cancer

BACKGROUND

The molecular era has identified four breast cancer subtypes. Luminal A breast cancer (LABC) is defined by estrogen-receptor positive (ER+), progesterone-receptor positive (PgR+) and human epidermal growth factor receptor-2 negative (HER2-) tumours; these cancers are the most common and carry favourable prognoses.

AIMS

To describe clinicopathologic features, oncological outcome and relapse patterns in LABC.

METHODS

Consecutive female patients diagnosed with ER/PgR+/HER2-, lymph node negative (LN-) breast cancer between 2005 and 2015 were included. Clinicopathological and recurrence data was recorded using descriptive statistics. Oncological outcome was determined using Kaplan-Meier and Cox-regression analyses.

RESULTS

Analysis was performed for 849 patients with median follow-up of 102.1 months. Mean disease-free (DFS) and overall survival (OS) were 85.8% and 91.8%. Seventy patients died during this study (8.2%), while 58 patients had recurrence; 7 had local recurrence (0.8%) and 51 had distant recurrence (DDR) (6.0%). Patients developing DDR were likely to be postmenopausal (P = 0.028), present symptomatically (P < 0.001) and have larger tumours (P < 0.001). The mean time to DDR was 65.7 months, with fatal recurrence occurring in 66.6% of patients with DDR (34/51). Systemic chemotherapy prescription did not influence DDR (P = 0.053). Age >65 (hazards ratio (HR):1.66, 95% Confidence Interval (CI):1.07-2.55, P = 0.022), presenting symptomatically (HR:2.28, 95%CI:1.21-4.29, P = 0.011) and tumour size >20 mm (HR:1.81, 95%CI:1.25-2.62, P = 0.002) predicted DFS, while age>65 (HR:2.60, 95%CI:1.49-4.53, P = 0.001) and being postmenopausal at diagnosis (HR:3.13, 95%CI:1.19-8.22, P = 0.020) predicted OS.

CONCLUSION

Our series demonstrated excellent survival outcomes for patients diagnosed with LN- LABC after almost a decade of follow-up. However, following DDR, fatal progression is often imminent.

Spectrally efficient optical orthogonal frequency division multiplexing

This paper charts the development of spectrally efficient forms of optical orthogonal frequency division multiplexing (OFDM) that are suited for intensity-modulated direct detection systems, such as wireless optical communications. The journey begins with systems using a DC-bias to ensure that no parts of the signal that modulates the optical source are negative in value, as negative optical intensity is unphysical. As the DC-part of the optical signal carries no information, it is wasteful in energy; thus asymmetrically clipped optical OFDM was developed, removing any negative-going peaks below the mean. Unfortunately, the clipping causes second-order distortion and intermodulation, so some subcarriers appear to be unusable, halving spectral efficiency; this is similar for unipolar and flipped optical OFDM. Thus, a considerable effort has been made to regain spectral efficiency, using layered techniques where the clipping distortion is mostly cancelled at the receiver, from a knowledge of one unpolluted layer, enabling one or more extra 'layers/paths/depths' to be received on the previously unusable subcarriers. Importantly, for a given optical power and high-order modulation, layered methods offer the best spectral efficiencies and need the lowest signal-to-noise ratios, especially if diversity combining is used. Thus, they could be important for high-bandwidth optical fibre systems. Efficient methods of generating all layers simultaneously, using fast Fourier transforms with their partial calculations extracted, are discussed, as are experimental demonstrations in both wireless and short-haul communications links. A musical analogy is also provided, which may point to how orchestral and rock music is deciphered in the brain. This article is part of the theme issue 'Optical wireless communication'.

Meta-analysis of the impact of progesterone receptor status on oncological outcomes in oestrogen receptor-positive breast cancer

BACKGROUND

Assessment of the oestrogen receptor (ER) provides important prognostic information in breast cancer. The impact of progesterone receptor (PgR) status is less clear. Standardization of immunohistochemical analysis of these receptors has reduced interstudy heterogeneity. The aim of this meta-analysis was to evaluate the impact of PgR negativity on outcomes in ER-positive (ER+) breast cancer.

METHODS

This study was performed according to PRISMA and MOOSE guidelines. PubMed, Embase and the Cochrane Library were searched systematically to identify studies comparing disease-free survival as the primary outcome and overall survival as secondary outcome between PgR-positive (PgR+) and PgR-negative (PgR-) status in ER+ breast cancer. A meta-analysis of time-to-effect measures from included studies was undertaken.

RESULTS

Eight studies including 13 667 patients, 11 838 in the ER+PgR+ group and 1829 in the ER+PgR- group, met the inclusion criteria. Treatment characteristics did not differ significantly between the two groups. Patients in the ER+PgR- group had a higher risk of disease recurrence than those who had ER+PgR+ disease (hazard ratio (HR) 1·57, 95 per cent c.i. 1·38 to 1·79; P < 0·001). This hazard was increased in patients with human epidermal growth factor receptor 2-negative tumours (HR 1·62, 1·37 to 1·93; P < 0·001). A similar result was observed for overall survival (HR 1·69, 1·33 to 2·14; P < 0·001).

CONCLUSION

PgR negativity is associated with significant reductions in disease-free and overall survival in ER+ breast cancer. Treatment and surveillance strategies in these patients should be tailored accordingly.

Optical sampling to enhance Nyquist-shaped signal detection under limited receiver bandwidth

Insufficient receiver bandwidth destroys the orthogonality of Nyquist-shaped pulses, generating inter-symbol interference (ISI). We propose using an optical pre-sampler to alleviate the requirement on the receiver bandwidth through pulse re-shaping. Experiments and simulations using an optically shaped 40-Gbaud Nyquist-shaped on-off-keying signal (N-OOK) show receiver sensitivity improvements of 4- and 7.1-dB under 18- and 11-GHz receiver electrical bandwidths, respectively.

Breast infections - Microbiology and treatment in an era of antibiotic resistance

INTRODUCTION

Primary breast abscesses occur in <1% of non-lactating women, rising to 11% in women with lactational mastitis. In patients undergoing breast cancer surgery, the inflammatory response to post-operative surgical site infection (SSI) has been implicated in recurrence. Anti-microbial resistance increasingly hampers treatment in each group.

AIMS

Describe the demographic and predisposing characteristics of patients with primary breast abscesses and secondary infections, identify the microbial and antimicrobial patterns and formulate an evidence-based protocol for treating breast infections.

METHODS

Retrospective cohort study of all breast infections (primary and post-operative) treated at UHL from 2014 to 2017. Data collected from microbiology databases and patient records was analysed using Minitab V18.

RESULTS

537 cultures from 108 patients were analysed. 47 (43.5%) had primary abscesses, 12 (11.1%) were lactational and 49 (45.4%) were post-operative SSI. For primary infections, the mean age was 41.9 (±12.2) and reinfection rate 33%. For SSIs the mean age was 51.8 (±14.52) and reinfection rate 11.8%. Overall, 29.3% were smokers, 6.4% diabetic and 2.9% pregnant. 60 (43%) patients required radiological drainage and 2 (1%) surgical drainage. 57.5% had mixed growth. The most common isolate was Staphylococcus aureus; cultured in 16.7% of primary abscesses and 24% of SSIs. 13 empiric antibiotic regimes were prescribed before 26.4% of patients changed to 12 different targeted regimes.

CONCLUSION

Breast infections are frequently polymicrobial with a wide variety of organisms isolated, suggesting the need for broad spectrum coverage until culture results become available. Based on our local culture results, the addition of clindamycin to flucloxacillin would provide excellent empiric coverage for all categories of breast infection. An evidence-based treatment guideline is required and should be formulated in close collaboration with microbiology specialists.

All-optical OFDM demultiplexing with optical partial Fourier transform and coherent sampling

We propose a novel scheme with a "time-lens"-based partial optical Fourier transform (OFT) and coherent sampling for high-speed complex orthogonal frequency-division multiplexing (OFDM) signal detection. Compared with all-optical OFDM demultiplexing with a matched optical filter, our proposed method replaces specialized optical filters with commercially available equipment, which relaxes stringent manufacturing and operational requirements. Our simulation shows that even with a partial OFT, theoretically, close to inter-channel interference-free performance is possible. In addition, we performed a proof-of-concept experiment of 16×10  Gbaud quadrature phase-shift keying (QPSK) all-optical OFDM detection, with all the bit error rates far below the 7% hard-overhead forward error correction limit.

The presentation, management and outcome of inflammatory breast cancer cases in the UK: Data from a multi-centre retrospective review

OBJECTIVES

Inflammatory Breast cancer (IBC) is a rare but aggressive form of breast cancer. Its incidence and behaviour in the UK is poorly characterised. We collected retrospective data from hospitals in the UK and Ireland to describe the presentation, pathology, treatment and clinical course of IBC in the UK.

MATERIALS AND METHODS

Patients with IBC diagnosed between 1997-2014 at fourteen UK and Irish hospitals were identified from local breast unit databases. Patient characteristics, tumour pathology and stage, and details of surgical, systemic and radiotherapy treatment and follow-up data were collected from electronic patient records and medical notes.

RESULT

This retrospective review identified 445 patients with IBC accounting for 0.4-1.8% of invasive breast cancer cases. Median follow-up was 4.2 years. 53.2% of tumours were grade 3, 56.2% were oestrogen receptor positive, 31.3% were HER2 positive and 25.1% were triple negative. 20.7% of patients had distant metastases at presentation. Despite trimodality treatment in 86.4%, 40.1% of stage III patients developed distant metastases. Five-year overall survival (OS) was 61.0% for stage III and 21.4% for stage IV patients.

CONCLUSIONS

This is the largest series of UK IBC patients reported to date. It indicates a lower incidence than in American series, but confirms that IBC has a high risk of recurrence with poor survival despite contemporary multi-modality therapy. A national strategy is required to facilitate translational research into this aggressive disease.

Meta-analysis of the diagnostic accuracy of ultrasound-guided fine-needle aspiration and core needle biopsy in diagnosing axillary lymph node metastasis

Background

Axillary lymph node status remains a significant prognostic indicator in breast cancer. Here, the diagnostic accuracy of ultrasound-guided fine-needle aspiration (US-FNA) and ultrasound-guided core needle biopsy (US-CNB) in axillary staging was compared.

Methods

A comprehensive search was undertaken of all published studies comparing the diagnostic accuracy of US-CNB and US-FNA of axillary lymph nodes in breast cancer. Studies were included if raw data were available on the diagnostic performance of both US-FNA and US-CNB, and compared with final histology results. Relevant data were extracted from each study for systematic review. Meta-analysis was performed using a random-effects model. The pooled sensitivity and specificity of US-FNA and US-CNB were obtained using a bivariable model. Summary receiver operating characteristic (ROC) graphs were created to confirm diagnostic accuracy.

Results

Data on a total of 1353 patients from six studies met the inclusion criteria and were included in the final analysis. US-CNB was superior to US-FNA in diagnosing axillary nodal metastases: sensitivity 88 (95 per cent c.i. 84 to 91) versus 74 (70 to 78) per cent respectively. Both US-CNB and US-FNA had a high specificity of 100 per cent. Reported complication rates were significantly higher for US-CNB compared with US-FNA (7·1 versus 1·3 per cent; P &lt; 0·001). Conversely, the requirement for repeat diagnostic procedures was significantly greater for US-FNA (4·0 versus 0·5 per cent; P &lt; 0·001).

Conclusion

US-CNB is a superior diagnostic technique to US-FNA for axillary staging in breast cancer.

All-optical digital-to-analog converter based on cross-phase modulation with temporal integration

We propose and experimentally demonstrate an all-optical digital-to-analog converter based on cross-phase modulation with temporal integration. The scheme is robust for driving signal noise due to the low-pass filtering feature of the temporal integrator. The proof-of-concept experiment demonstrates the generation of pulse-amplitude modulation (PAM) sequences up to eight levels. The performance of random PAM 2 and PAM 4 signals with different optical signal-to-noise ratios of the binary driving signal is also investigated. The scheme is scalable for high-speed operation with an appropriate dispersion profile of the nonlinear medium.

Investigating the association of rs2910164 with cancer predisposition in an Irish cohort

INTRODUCTION

MicroRNAs (miRNAs) are small noncoding RNA molecules that exert post-transcriptional effects on gene expression by binding with cis-regulatory regions in target messenger RNA (mRNA). Polymorphisms in genes encoding miRNAs or in miRNA-mRNA binding sites confer deleterious epigenetic effects on cancer risk. miR-146a has a role in inflammation and may have a role as a tumour suppressor. The polymorphism rs2910164 in the MIR146A gene encoding pre-miR-146a has been implicated in several inflammatory pathologies, including cancers of the breast and thyroid, although evidence for the associations has been conflicting in different populations. We aimed to further investigate the association of this variant with these two cancers in an Irish cohort.

METHODS

The study group comprised patients with breast cancer (BC), patients with differentiated thyroid cancer (DTC) and unaffected controls. Germline DNA was extracted from blood or from saliva collected using the DNA Genotek Oragene 575 collection kit, using crystallisation precipitation, and genotyped using TaqMan-based PCR. Data were analysed using SPSS, v22.

RESULTS

The total study group included 1516 participants. This comprised 1386 Irish participants; 724 unaffected individuals (controls), 523 patients with breast cancer (BC), 136 patients with differentiated thyroid cancer (DTC) and three patients with dual primary breast and thyroid cancer. An additional cohort of 130 patients with DTC from the South of France was also genotyped for the variant. The variant was detected with a minor allele frequency (MAF) of 0.19 in controls, 0.22 in BC and 0.27 and 0.26 in DTC cases from Ireland and France, respectively. The variant was not significantly associated with BC (per allele odds ratio = 1.20 (0.98-1.46), P  = 0.07), but was associated with DTC in Irish patients (per allele OR = 1.59 (1.18-2.14), P = 0.002).

CONCLUSION

The rs2910164 variant in MIR146A is significantly associated with DTC, but is not significantly associated with BC in this cohort.

Cycle-slip-less low-complexity phase recovery algorithm for coherent optical receivers

We propose and experimentally validate a blind phase recovery algorithm based on tracking low-frequency components of the phase noise, which we call "filtered carrier-phase estimation (F-CPE)." Tracking only the low-frequency components allows F-CPE to reduce the computational complexity by using a frequency-domain equalizer and to simplify the partitioning of a 16 quadrature amplitude modulation (16QAM) constellation. Further, this approach eliminates cycle slips by suppressing the impact of amplified spontaneous emission on phase noise estimation. The experimental results demonstrate cycle-slip-free operation for 15 and 32 GBd 16QAM signals. Additionally, the proposed method showed similar or better sensitivity compared with the blind-phase-search algorithm, near standard forward error correction thresholds of modern wavelength division multiplexing systems.

Impact of receptor phenotype on nodal burden in patients with breast cancer who have undergone neoadjuvant chemotherapy

Background

Optimal evaluation and management of the axilla following neoadjuvant chemotherapy (NAC) in patients with node‐positive breast cancer remains controversial. The aim of this study was to examine the impact of receptor phenotype in patients with nodal metastases who undergo NAC to see whether this approach can identify those who may be suitable for conservative axillary management.

Methods

Between 2009 and 2014, all patients with breast cancer and biopsy‐proven nodal disease who received NAC were identified from prospectively developed databases. Details of patients who had axillary lymph node dissection (ALND) following NAC were recorded and rates of pathological complete response (pCR) were evaluated for receptor phenotype.

Results

Some 284 patients with primary breast cancer and nodal metastases underwent NAC and subsequent ALND, including two with bilateral disease. The most common receptor phenotype was luminal A (154 of 286 tumours, 53·8 per cent), with lesser proportions accounted for by the luminal B–Her2 type (64, 22·4 per cent), Her2‐overexpressing (38, 13·3 per cent) and basal‐like, triple‐negative (30, 10·5 per cent) subtypes. Overall pCR rates in the breast and axilla were 19·9 per cent (54 of 271 tumours) and 37·4 per cent (105 of 281) respectively. Axillary pCR rates were highest in the Her2‐overexpressing group (27 of 35, 77 per cent) and lowest in the luminal A group (35 of 153, 22·9 per cent) (P < 0·001). Nodal burden (median number of positive nodes excised) was lower in the Her2‐overexpressing group compared with the luminal A group (0 versus 3; P < 0·001).

Conclusion

Her2 positivity was associated with increased rates of axillary pCR and reduced nodal burden following NAC.

Silicon microring modulator-based RF mixer for millimeter-wave phase-coded signal generation

Phase-coded radio frequency (RF) pulses are widely adopted for radar systems as an effective signal format to enable high-range resolution. However, generating such signals conventionally requires high-speed electronics and complex RF circuitry that impose burdens on the system cost and power consumption. In particular, modern radar systems desire features such as high frequencies, e.g., in the millimeter-wave region, high compactness, and high system flexibility, which pose great challenges for the conventional all-electronics solutions. In contrast, integrated microwave photonics opens a way to solutions that are able to provide those features simultaneously, together with potential for full integration and low cost fabrication. Here, we present an integrated microwave photonic method of a binary-phase-coded millimeter-wave signal generation. The core device is a silicon microring modulator with a device size of 0.13  mm×0.32  mm and a modulation bandwidth of 23 GHz. Using RF seed frequencies of 17.5 GHz and 20 GHz, respectively, we experimentally demonstrated the generation of binary-phase-coded signals at 35 GHz and 40 GHz using our proposed approach, the performance of which was verified by a pulse compression ratio of 94 and 106, respectively. The result of this work points to the realization of a chip-scale flexible millimeter-wave signal generator.

Prospective comparison of outcome after treatment for triple-negative and non-triple-negative breast cancer

INTRODUCTION

Triple-negative breast cancers (TNBC) are associated with a poor prognosis owing to an aggressive phenotype. We aimed to carry out a prospective study comparing management strategies and response to therapy in TNBC and non-TNBC patients.

METHODS

Data were obtained from a prospectively maintained database of patients treated for breast cancer.

RESULTS

A total of 142 TNBC and 142 age-, stage- and NPI-matched non-TNBC patients were treated. The difference in overall survival between the 2 groups was statistically significant (77% of TNBC patients alive at a mean follow-up of 32 months, versus 92% of non-TNBC patients at a mean follow-up of 38 months, P = 0.0 Log rank test). This survival difference was found to be independent of NPI (P = 0.0 Log rank test). Locoregional recurrence rates were similar between TNBC patients who were treated with wide local excision versus mastectomy (P = 0.449 Log rank test). A significant difference in survival was noted between TNBC patients who responded differentially to neoadjuvant chemotherapy (P = 0.035 Log rank test).

CONCLUSION

Patients with TNBC have adverse outcomes despite aggressive treatment. The development of effective targeted therapies is essential for this breast cancer subtype.

Nyquist pulse shaping using arrayed waveguide grating routers

We propose and demonstrate by simulations a novel Nyquist-WDM (N-WDM) superchannel transmitter based on an arrayed waveguide grating router (AWGR). This approach can generate Nyquist pulses at multiple wavelengths using a single AWGR. Results for a 3-channel 960-Gbit/s QPSK superchannel system show that a 10% guard band reduces the inter-channel interference (ICI) sufficiently. The design introduces less than 0.16-dB penalty when the waveguide loss is 2 dB/cm and 0.73-dB penalty when the standard deviation of phase error is 10°. Such Nyquist pulse shapers can be realised on a chip scale using photonic integrated circuits technology, and could be compactly integrated with other functional components to create single-chip N-WDM superchannel transmitters.

Banded all-optical OFDM super-channels with low-bandwidth receivers

We propose a banded all-optical orthogonal frequency division multiplexing (AO-OFDM) transmission system based on synthesising a number of truncated sinc-shaped subcarriers for each sub-band. This approach enables sub-band by sub-band reception and therefore each receiver's electrical bandwidth can be significantly reduced compared with a conventional AO-OFDM system. As a proof-of-concept experiment, we synthesise 6 × 10-Gbaud subcarriers in both conventional and banded AO-OFDM systems. With a limited receiver electrical bandwidth, the experimental banded AO-OFDM system shows 2-dB optical signal to noise ratio (OSNR) benefit over conventional AO-OFDM at the 7%-overhead forward error correction (FEC) threshold. After transmission over 800-km of single-mode fiber, ≈3-dB improvement in Q-factor can be achieved at the optimal launch power at a cost of increasing the spectral width by 14%.

Adrenocortical carcinoma surgery-surgical extent and approach

PURPOSE

Adequate tumour resection is the gold standard of care for adrenocortical carcinoma (ACC). However, the optimal surgical strategy remains debatable. In our opinion, the extent of surgery (adequate tumour resection) is the primary concern, rather than the surgical approach (laparoscopic or open). We propose that both surgical approaches have a role in the management of ACC provided the extent of resection is selected based on patient and tumour characteristics and accurate pre-operative investigations.

METHODS

A review of 25 curative intent resections for ACC between 2002 and 2013 was done. Group A (16 patients-64 %) included all patients who underwent planned radical adrenalectomy without any other resection and group B (9 patients-36 %) included all patients who underwent a planned extensive resection based on pre-operative investigations.

RESULTS

Of 471 adrenalectomies, 25 were performed for ACC with curative intent. Tumours were significantly larger in group B with mean size of 119.6 versus 62.4 mm in group A (p = 0.002). Tumours in group B also had higher WEISS scores (mean score 7 vs 5.2, p = 0.033) and almost always required multi-organ resection. The recurrence rate was 37.5 % (n = 6) for group A and 44.4 % for group B (n = 4), p = 1.00. Poor prognosis was associated with significantly higher WEISS scores (p = 0.016) and a trend towards more advanced ENSAT disease stage (p = 0.06). Estimated overall survival was 74.17 months (group A 67.3 vs group B 70.1, p = 0.244).

CONCLUSIONS

Accurate pre-operative staging is critical to select a tailored surgical strategy. Multi-organ resection remains the preferred approach for large and potentially invasive ACC. Some patients presenting with smaller ACC may benefit from a more extensive resection.

Photonic integrated circuit as a picosecond pulse timing discriminator

We report the first experimental demonstration of a compact on-chip optical pulse timing discriminator that is able to provide an output voltage proportional to the relative timing of two 60-ps input pulses on separate paths. The output voltage is intrinsically low-pass-filtered, so the discriminator forms an interface between high-speed optics and low-speed electronics. Potential applications include timing synchronization of multiple pulse trains as a precursor for optical time-division multiplexing, and compact rangefinders with millimeter dimensions.

Analysis of subsequent publication and impact of abstracts presented at the Sir Peter Freyer Surgical Symposium: Focus on the Plenary Session

BACKGROUND

The quality of abstracts presented at a conference reflects the academic activity and research productivity of the surgical/scientific association concerned. The abstract to publication rate (44.5 % internationally), is an important indicator of the quality of presented research.

AIM

To evaluate the publication rate and impact of abstracts presented at the plenary session of the Sir Peter Freyer Surgical Symposium over a 25-year period (1989-2014), and identify factors influencing publication.

METHODS

Plenary abstracts were identified from abstract books of the Symposium from 1989-2014. The authors, institution, subspecialty and research subject were recorded. A Medline search with name of the first and last author, key words and content of all abstracts was conducted to identify related publications. The impact factor (IF) of the journal and the time to publication was recorded.

RESULTS

298 presented abstracts resulted in 168 publications (publication rate: 56 %). Basic Science research accounted for 80 % (n = 237) of the total number of presentations with the remaining 20 % (n = 61) being categorised as clinical research. Overall, cancer research accounted for 48 % of presented work. The average time to publication was 2 ± 7 years, while 11 % of all published studies achieved publication in the year of the symposium. The median impact factor for published research was 3.558 (IF range 0-39).

CONCLUSION

These results indicate that the quality of papers presented at the Sir Peter Freyer Surgical Symposium compares favourably with international equivalents, making this meeting an important forum for Irish Academic Surgery.

Comparisons of spectrally-enhanced asymmetrically-clipped optical OFDM systems

Asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) is a technique that sacrifices spectral efficiency in order to transmit an orthogonally frequency-division multiplexed signal over a unipolar channel, such as a directly modulated direct-detection fiber or free-space channel. Several methods have been proposed to regain this spectral efficiency, including: asymmetrically clipped DC-biased optical OFDM (ADO-OFDM), enhanced U-OFDM (EU-OFDM), spectral and energy efficient OFDM (SEE-OFDM), Hybrid-ACO-OFDM and Layered-ACO-OFDM. This paper presents simulations up to high-order constellation sizes to show that Layered-ACO-OFDM offers the highest receiver sensitivity for a given optical power at spectral efficiencies above 3 bit/s/Hz. For comparison purposes, white Gaussian noise is added at the receiver, component nonlinearities are not considered, and the fiber is considered to be linear and dispersion-less. The simulations show that LACO-OFDM has a 7-dB sensitivity advantage over DC-biased OFDM (DCO-OFDM) for 1024-QAM at 87.5% of DCO-OFDM's spectral efficiency, at the same bit rate and optical power. This is approximately equivalent to a 4.4-dB advantage at the same spectral efficiency of 87.7% if 896-QAM were to be used for DCO-OFDM.

Time-lenses for time-division multiplexing of optical OFDM channels

Time-lenses provide a promising platform for novel, broadband optical signal processing. However, in order to minimize system penalties, design constraints must be adequately taken into account. We investigate the impact of third-order-dispersion and nonlinear distortion on the performance of time-lens-based communication systems for the first time. Here, we propose a novel application of time-lenses - temporal compression and time-division multiplexing of optical OFDM channels, to provide a 1 Tb/s superchannel. Time-lens system performance degradations are investigated in our proposed system and the results are applicable to all four wave mixing based time-lens systems. Our work can help to optimize time-lens based communication systems.

Improved polarization dependent loss tolerance for polarization multiplexed coherent optical systems by polarization pairwise coding

Polarization dependent loss (PDL) causes imbalanced optical signal to noise ratio (OSNR) of the two polarizations, thus remains one of the major bottlenecks for next-generation polarization-division-multiplexed (PDM) coherent optical transmission systems. In this paper, we investigate Pairwise Coding for adaptive PDL mitigation in PDM coherent optical systems. By pre-coding across two polarizations, the PDL-induced performance degradation can be largely mitigated without any coding overhead. We present details of the coding and de-coding design, and also derive the analytical symbol/bit error rate of the Polarization Pairwise Coding scheme, which can be used to predict the performance gain as well as for optimal rotation angle calculation. Simulation results verify that Pairwise Coding achieves substantial system performance gains over a wide range of PDL values. Compared with other digital coding techniques, Polarization Pairwise Coding shows improved performance than Walsh-Hadamard transform since it maximizes the coordinate diversity; and also Pairwise Coding is computationally much simpler to decode compared with the Golden and Silver Codes, therefore is practical for current 100-Gb/s and future 400-Gb/s and 1-Tb/s digital coherent transceivers.

Systems performance comparison of three all-optical generation schemes for quasi-Nyquist WDM

Orthogonal time division multiplexing (OrthTDM) interleaves sinc-shaped pulses to form a high baud-rate signal, with a rectangular spectrum suitable for multiplexing into a Nyquist WDM (N-WDM)-like signal. The problem with generating sinc-shaped pulses is that they theoretically have infinite durations, and even if time bounded for practical implementation, they still require a filter with a long impulse response, hence a large physical size. Previously a method of creating chirped-orthogonal frequency division multiplexing (OFDM) pulses with a chirped arrayed waveguide (AWG) filter, then converting them into interleaved quasi-sinc pulses using dispersive fiber (DF), has been proposed. This produces a signal with a wider spectrum than the equivalent N-WDM signal. We show that a modification to the scheme enables the spectral extent to be reduced for the same data rate. We then analyse the key factors in designing an OrthTDM transmitter, and relate these to the performance of a N-WDM system. We show that the modified transmitter reduces the required guard band between the N-WDM channels. We also simulate a simpler scheme using an unchirped finite-impulse response filter of similar size, which directly creates truncated-sinc pulses without needing a DF. This gives better system performance than either chirped scheme.

Widely-tunable low-phase-noise coherent receiver using an optical Wadley loop

The Wadley Loop is a method of down-converting RF signals over a wide frequency range using a low-quality widely-tunable oscillator and a high-stability frequency comb reference. Together the widely tunable oscillator and high-stability comb source provide a widely-tunable high-stability receiver. In this paper, we demonstrate an electro-optic version of the Wadley Loop that is able to provide a widely-tunable, high phase stability coherent receiver. This could have applications in Quadrature Amplitude Modulation (QAM) receivers with high constellation sizes, optical OFDM receivers with long symbol durations, and wide-range high spectral resolution optical spectrum analysers.

All-optical generation of DFT-S-OFDM superchannels using periodic sinc pulses

Discrete-Fourier-transform spread (DFT-S) optical Orthogonal Frequency Division Multiplexed (OFDM) signals offer improved nonlinearity performance in long haul optical communications systems, and can be used to form superchannels. In this paper we propose how DFT-S-OFDM superchannels can be generated and demultiplexed using all-optical techniques, and demonstrate the feasibility using numerical simulations. We also discuss how each wavelength channel is similar to recently proposed Orthogonally Time-Division Multiplexed (OrthTDM) systems using periodic-sinc pulses from, for example, a Nyquist laser. The key difference between OrthTDM and DFT-S-OFDM is the synchronization of the symbol boundaries of every modulation tributary; because of this we show that OrthTDM cannot be formed into superchannels that can be demultiplexed without penalties, but DFT-S-OFDM can be.

All-optical DAC using counter-propagating optical and electrical pulses in a Mach-Zehnder modulator

A novel method of converting binary-level electrical pulses into multi-level optical pulses using only a conventional traveling-wave optical modulator is presented. The method provides low inter-pulse interference due to the counter-propagating pulses, low amplitude noise, and a timing jitter determined chiefly by the quality of the optical pulse source. The method only requires one electrical drive per modulator and provides low-jitter variable-amplitude optical pulses that are suitable for shaping into a wide variety of modulation formats using a programmable optical filter.

Postmastectomy radiotherapy: indications and implications

BACKGROUND

Although breast conservation surgery, when combined with radiotherapy, has been shown to provide excellent locoregional control for breast cancer, approximately one third of women with breast cancer require mastectomy. Many of these women are offered immediate reconstruction. Postmastectomy radiotherapy (PMRT) is indicated in some cases, but is associated with side-effects, including its impact on the reconstructed breast.

OBJECTIVE

To review the pertinent issues surrounding PMRT, including patient selection for radiotherapy and the effect of radiotherapy on reconstructive decisions.

METHODS

A literature review was performed using the Medline database.

CONCLUSIONS

PMRT is indicated in patients who are deemed to have a high risk of loco-regional recurrence. Although PMRT is strongly recommended for patients with four or more positive lymphnodes, other indications for PMRT remain controversial. Immediate reconstruction post mastectomy has been shown to have favorable outcomes. However, PMRT may increase the need for revision surgery post immediate reconstruction. There are few randomized trials looking at these key issues, and the evidence is largely derived from observational retrospective studies. Patients should be carefully counseled before a decision is made to proceed with immediate reconstruction, where there is a high chance that PMRT may be indicated.

Flexible all-optical frequency allocation of OFDM subcarriers

We investigate the underlying mechanism that allows OFDM subcarriers in an all-optical OFDM system to be assigned to any optical frequency using an optical filter, even if that frequency is not generated by the comb-line source feeding the filters. We confirm our analysis using simulations, and present experimental results from a 252-subcarrier system that uses a mode-locked laser (MLL) as the comb source and a wavelength selective switch. The experimental results show that there is no correlation between the programmed frequency offset between a subcarrier and nearest comb line, and the received signal quality. Thus, subcarriers could be inserted into unused portions of an optical transmission system's spectrum without restriction on their particular center frequencies. Any percentage of cyclic prefix can be added to the OFDM symbol simply by reprogramming the optical filter to give wider subcarrier frequency spacing than the comb line spacing, which is useful for tailoring the CP to the dispersion of various optical transmission paths, to maximize the spectral efficiency. Finally, the MLL's center frequency need not be locked to a system reference.

Breast clinic referrals: can mastalgia be managed in primary care?

BACKGROUND

Centralisation of breast cancer services in Ireland has resulted in a significant increase in the number of patients attending symptomatic breast units (SBU). A considerable proportion of patients referred to SBU present with non-suspicious symptoms and fall into a "low-risk" category for breast cancer. It has been proposed that consideration be given to a primary care-delivered service for these patients.

AIM

To evaluate SBU attendances and correlate with diagnosis to identify a cohort of patients who may be suitable for management in the primary care setting.

METHODS

Data were collected from a prospectively maintained database on patients attending SBU at two tertiary referral centres (Beaumont Hospital and University College Hospital Galway) from January 2011 to 2012. Reasons for attendance, outcome of triple-assessment and incidence of malignancy were analysed.

RESULTS

14,325 patients underwent triple assessment at the SBU in this time period. 5,841 patients were referred with mastalgia, of whom 3,331 (57 %) reported mastalgia as the only symptom. The incidence of breast cancer in patients presenting with mastalgia alone was 1.2 %. All patients diagnosed with breast cancer in this cohort were over 35 years of age.

CONCLUSION

The incidence of breast cancer in patients referred to SBU with mastalgia as an isolated symptom is extremely low. Patients under 35 years of age, with mastalgia as an isolated symptom do not require breast imaging and have a sufficiently low risk of breast cancer that they may be suitable for management in the primary care setting.

Abstract P2-18-05: Axillary nodal burden in patients with a positive pre-operative ultrasound guided fine needle aspiration cytology

Introduction

Recent years have seen a dramatic shift to more conservative management of the axilla and the presence of a positive sentinel lymph node biopsy does not now automatically mandate an axillary clearance. This is based largely on data from the American College of Surgeons Oncology Group (ACOSOG) Z11 study, which failed to demonstrate a difference in local recurrence or overall survival when an axillary clearance was omitted in a highly selective group of patients with a positive sentinel lymph node. However, the presence of a positive pre-operative ultrasound guided axillary FNAC(Fine Needle Aspiration Cytology) may be representative of a higher burden of axillary disease.

Aim

Therefore, the aims of this study were firstly to quantify the actual nodal burden in breast cancer patients with a positive pre-operative ultrasound guided axillary FNAC and secondly to identify the number of patients who may have been spared an axillary clearance based on Z11 eligibility criteria.

Methods

A retrospective review of a prospectively maintained database within a tertiary breast cancer referral centre was performed. All patients with a positive pre-operative axillary FNAC were identified within a five year period (2007 – 2011). Demographic, tumour and biological characteristics and final nodal status were analysed. Eligibility for randomisation according to the Z11 criteria was assessed based on the final pathology and the number of patients who could have been spared an axillary clearance was identified.

Results

A total of 360 patients were identified with a positive axillary ultrasound guided FNAC. Sixty-three patients had no axillary surgery and three patients had recurrent disease, leaving a total of 294 for analysis. The mean age was 56 years (range 22 – 87). The mean size of the tumour was 31.3mm (range 4mm – 132mm) and the majority were an invasive grade 3 (57%) ductal carcinoma (84%). Luminal A (63%) was the commonest sub-type. The mean number of nodes removed at axillary clearance was 24 (range 7 – 58) while the mean number of positive nodes excised was 6 (range 0 – 47). Of these, the mean number of level I positive nodes was 4, level II was 1 and level III nodes was &lt;1.

Overall a total of 78 patients had less than three positive nodes identified in the axilla and potentially may have been eligible for the Z11 study. However, when patients who had a mastectomy, neo-adjuvant chemotherapy were excluded and the presence of extra-capsular nodal involvement was accounted for only 19 (6.4%) patients may have been spared an axillary clearance.

Conclusions

The presence of nodal positivity on a pre-operative FNAC is associated with a higher burden of axillary disease. Only a minority of these patients would be able to avoid an axillary clearance in the setting of the recent Z11 study. Performing an axillary ultrasound and FNAC of suspicious nodes allows patients to avoid an unnecessary sentinel lymph node biopsy and proceed directly to an axillary clearance.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-18-05.

Paediatric surgery--a general hospital experience

Plans to centralise paediatric surgery in Ireland have potentially significant implications for service provision and surgical training. study assesses the workload of paediatric surgery in a district hospital over a five-year period. Paediatric surgical admissions and procedures at Mayo General Hospital from January 2006 - December 2010 were reviewed. Data was obtained from the Hospital inpatient enquiry (HIPE) systems and theatre logbooks. 4,255 surgical procedures were performed in 3981 paediatric patients, accounting for 7.4% of the total surgical workload. 2,578 (65%) of cases were elective and 1403 (35%) of paediatric surgery was performed in the emergency setting; paediatric appendicectomy was the most commonly performed procedure (n = 554) with a complication rate of 2.5%. There were no paediatric surgery related mortalities. Paediatric surgery represents a significant part of the surgical workload. There is a continued need for general paediatric surgical provision in this regional setting, supported by access to specialist centres for complicated paediatric surgery.

Management of the acute appendix mass: a survey of surgical practice

Management of the appendix mass is controversial with no consensus in the literature. Traditionally, the approach has been conservative followed by interval appendicectomy. A survey was distributed to 117 surgeons (100 consultants and 17 final year specialist registrars) to determine how the appendix mass is currently treated in Ireland. In total, 70 surgeons responded. 51 (73%) adopt a conservative approach initially. 48 (68%) favoured interval appendicectomy at six weeks after a period of successful conservative management. 34 (49%) gave risk of recurrence as the reason for performing interval appendicectomy and 16 (22%) would perform interval appendicectomy in order to obtain histological analysis to outrule caecal or appendiceal neoplasm. 44 (63%) opted for a laparoscopic rather than an open approach for interval appendicectomy. No consensus exists in Ireland for management of the appendix mass presenting acutely. The present series demonstrates a trend towards conservative approach initially followed by interval appendicectomy.

Successful introduction of ring-fenced inpatient surgical beds in a general hospital setting

This study aimed to assess the impact of ring-fenced inpatient general surgical beds on day of surgery (DOS) admission, duration of elective inpatient stay (DEIS), and cancellation rates over a 6 month period. In June 2010 17 of 60 surgical inpatient beds were decommissioned. The remainder (43) were ring-fenced for general surgery patients only. Comparative analysis examining admission rates, cancellation rates, and theatre activity was performed between a reference period (January-June 2010) and the study period (July-December 2010). Complexity of all operations was graded according to an index schedule of procedures. There was no difference between the reference and study periods in volumes of elective admissions (472 [53.03%] vs. 418 [4797%]) and emergency admissions (928 [50.03%] vs. 927 [49.97%]). DOS admissions increased 5-fold during the study period (38 [8.1%] vs. 190 [45.5%], P < 0.001). Average duration of elective inpatient stay reduced from 4.3 days to 3.06 days in the study period (P < 0.001). No difference was observed in volume of operations performed at all levels of complexity. There were 78 (58.2%) cancellations during the reference period and 56 (41.8%) during the study period with patient non-attendance the most common cause for cancellation in both periods. Ring-fenced surgical beds facilitated higher DOS admission rates and shorter duration of elective inpatient stay, leading to more efficient use of hospital resources.

Inserting a cyclic prefix using Arrayed-Waveguide Grating Routers in all-optical OFDM transmitters

Arrayed-Waveguide Grating Routers (AWGR) can be used as multiplexers and demultiplexers in optical OFDM systems, as they provide both the serial-to-parallel converter and the optical Fourier transform in one component. This paper shows how the design of the AWGR at the transmitter can be modified to insert a cyclic prefix or postfix (CP). We use simulations of a 4-subcarrier system to compare systems without the CP, with a guard-interval, and with a CP. We show that the CP greatly improves the orthogonality of the subcarriers and resilience to timing errors. Furthermore, the CP allows for uncompensated fiber dispersion, especially if the relative timing of the subcarriers upon transmission is adjusted.

All-optical OFDM transmitter design using AWGRs and low-bandwidth modulators

An Arrayed-Waveguide Grating Router (AWGR) can be used as a demultiplexer for an optical OFDM system, as it provides both the serial-to-parallel converter and the optical Fourier transform (FT) in one component. Because an inverse FT is topologically identical to a Fourier transform, the AWGR can also be used as a FT in an OFDM transmitter. In most all-optical OFDM systems the optical modulators are fed with CW tones; however, the subcarriers (SC) will only be perfectly orthogonal if the bandwidth of the data modulators is similar to the total bandwidth of all subcarriers. Using simulations, this paper investigates the reduction in modulator bandwidth that could be achieved if the modulators are placed before an AWGR designed as a FT. This arrangement also allows the complex (IQ) modulators to be replaced with simpler and more-compact phase modulators. We show that these design improvements enable 7.5-GHz bandwidth modulators to be used in a 4 × 10 Gsymbol/s (80 Gbit/s) per polarization per wavelength system.

NCCP breast cancer referral guidelines--are breast cancer patients prioritised?

Following centralisation of breast cancer services, the National Cancer Control Programme (NCCP) introduced referral guidelines indicating which patients require urgent, early and routine review. This study prospectively analysed referrals to a symptomatic breast unit over 3 months to measure Primary Care Physician (GP) uptake of the NCCP referral guidelines, compare triage patterns of GP and consultant breast surgeon and evaluate the efficacy of the guidelines at identifying patients with breast cancer. 1044 consecutive referrals were categorised according to NCCP guidelines. 637 (61%) were referred using the NCCP form. GP referrals correlated well with consultant breast surgeon for patients requiring urgent review (r = 0.71, p < 0.001; Pearson). Patients categorised as "urgent" were more likely to have a breast biopsy compared to those categorised as "routine" (p < 0.0001; Chi2). The overall cancer incidence was 34 (3.3%) and significantly higher in the "urgent" group at 10.5%. NCCP guidelines were 91% sensitive for triaging breast cancer patients into the correct (urgent) category. The NCCP guidelines are accurate and should be considered the gold-standard for referral to the symptomatic breast service. Consideration should be given to a GP-delivered service to patients outside the "urgent" category.

Design of Arrayed-Waveguide Grating Routers for use as optical OFDM demultiplexers

All-optical OFDM uses optical techniques to multiplex together several modulated lightsources, to form a band of subcarriers that can be considered as one wavelength channel. The subcarriers have a frequency separation equal to their modulation rate. This means that they can be demultiplexed without any cross-talk between them, usually with a Discrete Fourier Transform (DFT), implemented optically or electronically. Previous work has proposed networks of optical couplers to implement the DFT. This work shows that the topology of an Arrayed Grating Waveguide Router (AWGR) can be used to perform the demultiplexing, and that the AWGR can be considered as a serial-to-parallel converter followed by a DFT. The simulations show that the electrical bandwidths of the transmitter and receiver are critical to orthogonal demultiplexing, and give insight into how crosstalk occurs in all-optical OFDM and coherent-WDM systems using waveforms and spectra along the system. Design specifications for the AWGR are developed, and show that non-uniformity will lead to crosstalk. The compensation of dispersion and the applications of these techniques to 'coherent WDM' systems using Non-Return to Zero modulation is discussed.

Experimental demonstration of a flexible and stable semiconductor laser linewidth emulator

We propose and demonstrate experimentally a laser source whose linewidth is adjustable independently of its other characteristics. This source can be used to test whether a particular laser would be suitable in a system, without the need to purchase several different lasers. It also has the advantage that the linewidth is generated digitally so it is extremely stable over time. We demonstrate a dialed-linewidth emulator between 256 kHz to 150 MHz. The narrowest linewidth shown by this technique is the original linewidth of the semiconductor laser source used in the setup. We also investigate the effect of driving our modulator into its nonlinear range.

Amplified-spontaneous noise limit of optical OFDM lightwave systems

Optical Orthogonal Frequency Division Multiplexing (O-OFDM) systems use electronic digital computation to provide dispersion compensation that can be rapidly adapted to changes in the optical link or optical network. Recent demonstrations have shown compensation of several thousand kilometers. Earlier simulations and analysis showed better sensitivities than non-return to zero systems; however, they assumed optical filters with very narrow bandwidths and narrow-linewidth lasers. This paper explores the effect of the optical filter bandwidths and laser linewidths for both coherent and direct-detection systems using analysis and simulations.