Abstract P3-01-11: Sentinel lymph node (SLN) localization is highly successful after neoadjuvant chemotherapy (NCT) for breast cancer

Background: Recent multi-center trial results are concerning for the ability to identify SLNs after NCT. SLN localization was shown to be less successful (80%) after NCT when compared with no NCT (99%) (SENTINA), and the SLN identification rate in Z1071 in which all patients received NCT was 93%.

Purpose: To examine the effect of NCT, patient and disease characteristics, imaging and surgical technique on SLN localization rates in breast cancer patients undergoing chemotherapy.

Methods: Retrospective, single institution study was performed on patients who underwent surgery for breast cancer from January 2008 to December 2013. All patients who underwent SLN biopsy and either adjuvant chemotherapy (ACT) or NCT, were included. All patients underwent lymphoscintigraphy, and SLN biopsy was performed with the definitive breast surgery.

Results: 68 patients underwent NCT, and 133 underwent ACT. Our SLN localization rate was 198/201 (98.5%) overall; 98.6% (67 of 68) with NCT and 97.7% (130/133) with ACT (p=1.0). Compared with the NCT group, the ACT patients were significantly older, white, with more ER/PR positive tumors. The NCT group had more positive nodes on preop imaging (64% v. 20%, p<0.001), FNA (82% v. 22%, p<0.001), and a lower use of blue dye (37% v. 61%, p=0.05) but there were no differences in the number of SLN removed (1.43 v. 1.33 p=0.32), or nodes that were positive on intraoperative evaluation (30 v. 33%, p=0.75). Comparing the patients who had successful and failed SLN localization, there were no differences in demographics, tumor type, Stage, prior breast surgery, preoperative node positivity on imaging or FNA or timing of chemotherapy.

Conclusion: In this single institution series, SLN non-localization was a rare event and not associated with NCT. We were unable to identify any patient or disease characteristics, imaging or surgical techniques associated with SLN non-localization. The etiology of the lower SLN identification rates with NCT in multi-institutional trials remains to be elucidated.

Citation Format: Sugg S, Hayes R, Gbenon A, Lizarraga I, Erdahl L, Weigel R, Liao J, Menda Y, Scott-Conner C. Sentinel lymph node (SLN) localization is highly successful after neoadjuvant chemotherapy (NCT) for breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-01-11.

Delineation of interspecific epistasis on fiber quality traits in Gossypium hirsutum by ADAA analysis of intermated G. barbadense chromosome substitution lines

Genetic diversity is the foundation of any crop improvement program, but the most cultivated Upland cotton [Gossypium hirsutum L., 2n = 52, genomic formula 2(AD)(1)] has a very narrow gene pool resulting from its evolutionary origin and domestication history. Cultivars of this cotton species (G. hirsutum L.) are prized for their combination of exceptional yield, other agronomic traits, and good fiber properties, whereas the other cultivated 52-chromosome species, G. barbadense L. [2n = 52, genomic formula 2(AD)(2)], is widely regarded as having the opposite attributes. It has exceptionally good fiber qualities, but generally lower yield and less desirable agronomic traits. Breeders have long aspired to combine the best attributes of G. hirsutum and G. barbadense, but have had limited success. F(1) hybrids are readily created and largely fertile, so the limited success may be due to cryptic biological and technical challenges associated with the conventional methods of interspecific introgression. We have developed a complementary alternative approach for introgression based on chromosome substitution line, followed by increasingly sophisticated genetic analyses of chromosome-derived families to describe the inheritance and breeding values of the chromosome substitution lines. Here, we analyze fiber quality traits of progeny families from a partial diallel crossing scheme among selected chromosome substitution lines (CS-B lines). The results provide a more detailed and precise QTL dissection of fiber traits, and an opportunity to examine allelic interaction effects between two substituted chromosomes versus one substituted chromosome. This approach creates new germplasm based on pair wise combinations of quasi-isogenic chromosome substitutions. The relative genetic simplicity of two-chromosome interactions departs significantly from complex or RIL-based populations, in which huge numbers of loci are segregating in all 26 chromosome pairs. Data were analyzed according to the ADAA genetic model, which revealed significant additive, dominance, and additive-by-additive epistasis effects on all of the fiber quality traits associated with the substituted chromosome or chromosome arm of CS-B lines. Fiber of line 3-79, the donor parent for the substituted chromosomes, had the highest Upper Half Mean length (UHM), uniformity ratio, strength, elongation, and lowest micronaire among all parents and hybrids. CS-B16 and CS-B25 had significant additive effects for all fiber traits. Assuming a uniform genetic background of the CS-B lines, the comparative analysis of the double-heterozygous hybrid combinations (CS-B × CS-B) versus their respective single heterozygous combinations (CS-B × TM-1) demonstrated that interspecific epistatic effects between the genes in the chromosomes played a major role in most of the fiber quality traits. Results showed that fiber of several hybrids including CS-B16 × CS-B22Lo, CS-B16 × CS-B25 and CS-B16 × TM-1 had significantly greater dominance effects for elongation and hybrid CS-B16 × CS-B17 had higher fiber strength than their parental lines. Multiple antagonistic genetic effects were also present for fiber quality traits associated with most of the substituted chromosomes and chromosome arms. Results from this study highlight the vital importance of epistasis in fiber quality traits and detected novel effects of some cryptic beneficial alleles affecting fiber quality on the 3-79 chromosomes, whose effects were not detected in the 3-79 parental lines.

Increased risk of HIV-infection among school-attending orphans in rural Zimbabwe

In Zimbabwe around 1.1 million children have been orphaned due to AIDS. We conducted a survey among school-attending youth in rural south-eastern Zimbabwe in 2003, and examined the association between orphaning and risk of HIV. We enrolled 30 communities in three provinces. All students attending Year 2 of secondary school were eligible. Each completed a questionnaire and provided a finger-prick blood specimen for testing for HIV-1 and HSV-2 antibodies. Female participants were tested for pregnancy. Six thousand seven hundred and ninety-one participants were recruited (87% of eligible); 35% had lost one or both parents (20% of participants had lost their father; 6% their mother; and 9% both parents). Orphans were not poorer than non-orphans based on reported access to income, household structure and ownership of assets. There was strong evidence that orphans, and particularly those who had lost both parents, were at increased sexual risk, being more likely to have experienced early sexual debut; to have been forced to have sex; and less likely to have used condoms. Fifty-one students were HIV positive (0.75%). Orphans were three times more likely to be HIV infected than non-orphans (adjusted odds ratio = 3.4; 95% confidence interval: 1.8-6.6). Over 60% of those HIV positive were orphaned. Among school-going youth, the rates of orphaning were very high; there was a strong association between orphaning and increased risk of HIV, and evidence of greater sexual risk taking among orphans. It is essential that we understand the mechanisms by which orphaned children are at increased risk of HIV in order to target prevention and support appropriately.

Association of metabolic gene polymorphisms with alcohol consumption in controls

The objectives were to study the association between metabolic genes involved in alcohol metabolism (CYP2E1 RsaI, CYP2E1 DraI, ADH1C, NQO1) and alcohol consumption in a large sample of healthy controls. Healthy subjects were selected from the International Collaborative Study on Genetic Susceptibility to Environmental Carcinogens (GSEC). Subjects with information on both alcohol consumption and at least one of the studied polymorphisms were included in the analysis (n=2224). Information on the amount of alcohol consumption was available for a subset of subjects (n=844). None of the studied genes was significantly associated with drinking habits. A significant heterogeneity with age was observed when studying the association between CYP2E1 RsaI and alcohol drinking. CYP2E1 RsaI polymorphism was significantly associated with being a never drinker at older ages (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.2-4.8; at ages above 68 years), while the association was reversed at ages below 47 years (OR 0.5, 95% CI 0.2-1.4). For subjects with detailed information on alcohol intake, no association between alcohol quantity and polymorphisms in metabolic genes was observed; subjects carrying the NQO1 polymorphism tended to drink more than subjects carrying the wild-type alleles. Therefore, no significant association between CYP2E1 RsaI, CYP2E1 DraI, ADH1C, NQO1 polymorphisms and alcohol consumption was observed in healthy controls.

Alternatives to randomisation in the evaluation of public-health interventions: statistical analysis and causal inference

BACKGROUND

In non-randomised evaluations of public-health interventions, statistical methods to control confounding will usually be required. We review approaches to the control of confounding and discuss issues in drawing causal inference from these studies.

METHODS

Non-systematic review of literature and mathematical data-simulation.

RESULTS

Standard stratification and regression techniques will often be appropriate, but propensity scores may be useful where many confounders need to be controlled, and data are limited. All these techniques require that key putative confounders are measured accurately. Instrumental variables offer, in theory, a solution to the problem of unknown or unmeasured confounders, but identifying an instrument which meets the required conditions will often be challenging. Obtaining measurements of the outcome variable in both intervention and control groups before the intervention is introduced allows balance to be assessed, and these data may be used to help control confounding. However, imbalance in outcome measures at baseline poses challenges for the analysis and interpretation of the evaluation, highlighting the value of adopting a design strategy that maximises the likelihood of achieving balance. Finally, when it is not possible to have any concurrent control group, making multiple measures of outcome pre- and postintervention can enable the estimation of intervention effects with appropriate statistical models.

CONCLUSION

For non-randomised designs, careful statistical analysis can help reduce bias by confounding in estimating intervention effects. However, investigators must report their methods thoroughly and be conscious and critical of the assumptions they must make whenever they adopt these designs.

Bacterial vaginosis in female facility workers in north-western Tanzania: prevalence and risk factors

OBJECTIVES

To determine prevalence of, and risk factors for, bacterial vaginosis (BV) among herpes simplex virus (HSV) 2 seropositive Tanzanian women at enrollment into a randomised, placebo-controlled trial of HSV suppressive treatment.

METHODS

1305 HSV-2 seropositive women aged 16-35 years working in bars, guesthouses and similar facilities were interviewed, examined and tested for HIV, syphilis, Neisseria gonorrhoeae, Chlamydia trachomatis, BV, candidiasis and trichomoniasis. Factors associated with BV were analysed using logistic regression to estimate odds ratios and 95% confidence intervals.

RESULTS

BV prevalence was 62.9%; prevalence of Nugent score 9-10 was 16.1%. Independent risk factors for BV were work facility type, fewer dependents, increasing alcohol consumption, sex in the last week (adjusted OR 2.03; 95% CI 1.57 to 2.62), using cloths or cotton wool for menstrual hygiene, HIV (adjusted OR 1.41; 95% CI 1.09 to 1.83) and Trichomonas vaginalis infection. There was no association between BV and the frequency or method of vaginal cleansing. However, BV was less prevalent among women who reported inserting substances to dry the vagina for sex (adjusted OR 0.44; 95% CI 0.25 to 0.75).

CONCLUSION

BV was extremely prevalent among our study population of HSV-2 positive female facility workers in North-western Tanzania. Although recent sex was associated with increased BV prevalence, vaginal drying was associated with lower BV prevalence. Further studies of the effects of specific practices on vaginal flora are warranted.

Alternatives to randomisation in the evaluation of public health interventions: design challenges and solutions

BACKGROUND

There has been a recent increase in interest in alternatives to randomisation in the evaluation of public health interventions. We aim to describe specific scenarios in which randomised trials may not be possible and describe, exemplify and assess alternative strategies.

METHODS

Non-systematic exploratory review.

RESULTS

In many scenarios barriers are surmountable so that randomised trials (including stepped-wedge and crossover trials) are possible. It is possible to rank alternative designs but context will also determine which choices are preferable. Evidence from non-randomised designs is more convincing when confounders are well-understood, measured and controlled; there is evidence for causal pathways linking intervention and outcomes and/or against other pathways explaining outcomes; and effect sizes are large.

CONCLUSION

Non-randomised trials might provide adequate evidence to inform decisions when interventions are demonstrably feasible and acceptable, and where evidence suggests there is little potential for harm, but caution that such designs may not provide adequate evidence when intervention feasibility or acceptability is doubtful, and where existing evidence suggests benefits may be marginal and/or harms possible.

Sexual behaviour and HIV/sexually transmitted infection risk behaviours in the general population of Slovenia, a low HIV prevalence country in central Europe

Objectives:

To describe sexual and HIV/sexually transmitted infection (STI) risk behaviours in Slovenia.

Methods:

A nationally representative cross-sectional survey of the general population aged 18–49 years in 1999–2001 was conducted. The data were collected by face-to-face interviews and anonymous self-administered questionnaires. Statistical methods for complex survey data were used.

Results:

849 men and 903 women were interviewed. In the past 5 years, both men and women reported a median of one heterosexual partner (means 3.2, 1.5, respectively), concurrent heterosexual partnerships were reported by 24.4% of men and 8.2% of women, heterosexual sex with non-Slovenian partners by 12.6% of men and 12.2% of women, forced sex by 4.8% of women, paid heterosexual sex by 2.6% of men, sex with another man by 0.6% of men and heterosexual sex with an injecting drug user by 1.2% of men and 1.3% of women. In the past year, 22.7% of men and 9.5% of women reported forming at least one new heterosexual partnership. The mean numbers of episodes of heterosexual sex in the previous 4 weeks were 6.1 for men and 6.0 for women. Consistent and inconsistent condom use was reported more frequently among men reporting multiple female partners and those not married or cohabiting.

Conclusions:

Recent patterns of reported sexual behaviour are consistent with a low risk of HIV and STI transmission in Slovenia. The results will inform Slovenian sexual health policies including HIV/STI prevention, and are particularly valuable because population-based data on HIV/STI risk behaviour have not previously been available in low HIV prevalence countries of central Europe.

Complex physiological traits as biomarkers of the sub-lethal toxicological effects of pollutant exposure in fishes

Complex physiological traits, such as routine aerobic metabolic rate or exercise performance, are indicators of the functional integrity of fish that can reveal sub-lethal toxicological effects of aquatic pollutants. These traits have proved valuable in laboratory investigations of the sub-lethal effects of heavy metals, ammonia and various xenobiotics. It is not known, however, whether they can also function as biomarkers of the complex potential range of effects upon overall functional integrity caused by exposure to mixtures of chemicals in polluted natural environments. The current study used portable swimming respirometers to compare exercise performance and respiratory metabolism of fish exposed in cages for three weeks to either clean or polluted sites on three urban European river systems: the river Lambro, Milan, Italy; the rivers Blythe, Cole and Tame, Birmingham, UK; and the river Amstel, Amsterdam, The Netherlands. The UK and Italian rivers were variously polluted with high levels of both bioavailable heavy metals and organics, and the Amstel by mixtures of bioavailable organics at high concentrations. In both the UK and Italy, indigenous chub (Leuciscus cephalus) exposed to clean or polluted sites swam equally well in an initial performance test, but the chub from polluted sites could not repeat this performance after a brief recovery interval. These animals were unable to raise the metabolic rate and allocate oxygen towards exercise in the second trial, an effect confirmed in successive campaigns in Italy. Swimming performance was therefore a biomarker indicator of pollutant exposure in chub exposed at these sites. Exposure to polluted sites on the river Amstel did not affect the repeat swimming performance of cultured cloned carp (Cyprinus carpio), indicating either a species-specific tolerance or relative absence of heavy metals. However, measurements of oxygen uptake during swimming revealed increased rates of routine aerobic metabolism in both chub and carp at polluted sites in all of the rivers studied, indicating a sub-lethal metabolic loading effect. Therefore, the physiological traits of exercise performance and metabolic rate have potential as biomarkers of the overall sub-lethal toxic effects of exposure to complex mixtures of pollutants in rivers, and may also provide insight into why fish do not colonize some polluted environments.

The cardiovascular and pharmacokinetic profile of dofetilide in conscious telemetered beagle dogs and cynomolgus monkeys

BACKGROUND AND PURPOSE

The effects of dofetilide were studied in monkeys and dogs. Pharmacokinetic data were generated together with the monitoring of cardiovascular changes in order to compare effects relative to human exposure.

EXPERIMENTAL APPROACH

Beagle dogs and cynomolgus monkeys were telemetered to collect arterial blood pressure, heart rate and ECG for 6 h after selected oral doses of dofetilide. Pharmacokinetic parameters were determined for each dose.

KEY RESULTS

Dogs: increases in the QT(c) interval reached 56 ms in dogs dosed with 0.3 mg kg(-1) of dofetilide. Premature ventricular contractions and right bundle branch block were evident at this dose, without changes in cardiovascular parameters. The mean C(max) values were 3.35 and 60.15 ng mL(-1) at doses of 0.03 and 0.3 mg kg(-1), respectively. Monkeys: increases in QT(c) intervals reached 40-50 ms after 0.03 mg kg(-1). T-wave changes were observed after 0.03 mg kg(-1) without changes in cardiovascular parameters. The mean C(max) values following oral doses of 0.01 and 0.03 mg kg(-1) were 0.919 ng mL(-1) and 1.85 ng mL(-1), respectively.

CONCLUSIONS AND IMPLICATIONS

Despite dofetilide exposure comparable to that in humans, QT(c) responses in dogs were greater than those reported in humans. A comparable human dose used in the monkey achieved only half of the exposure but was associated with twofold greater increases in QT(c). Our data support the view that safety risk assessments of new drugs in animal models should ensure that the clinical therapeutic range of exposure is achieved and any untoward effects interpreted accordingly.

Comparison of multiple-locus variable-number tandem repeat analysis and pulsed-field gel electrophoresis in a setting of polyclonal endemicity of vancomycin-resistant Enterococcus faecium

In order to assess whether multiple-locus-variable number tandem repeat analysis (MLVA) could replace pulsed-field gel electrophoresis (PFGE) for genotyping vancomycin-resistant isolates of Enterococcus faecium (VREF), this study compared the typeability, discriminatory power, concordance and costs of these methods for VREF isolates obtained from patients, environmental samples and the hands of healthcare workers (HCWs) in a medical intensive care unit (ICU) where VREF was endemic. Over a 58-day period, 393 VREF isolates (373 vanA, one vanA/B, 19 vanB) were cultured from patient rectal swabs (n = 76), the environment (n = 270) and the hands of HCWs (n = 47). PFGE was able to divide 358 (91.1%) isolates into 19 PFGE types (>six bands different) and 24 subtypes (one to three bands different). MLVA was able to type 391 (99.5%) isolates into 11 genotypes. The discriminatory power of PFGE subtypes was 83%, as compared to 68% for MLVA. Concordance between the two methods, based on matched or mismatched MLVA types and PFGE types or subtypes, was 67.5% and 82.8%, respectively. Using PFGE, 13 isolates could be genotyped in 3 days; MLVA genotyped 94 isolates in 2 days. For both methods, the estimated costs were Euro 7 ($10)/isolate. PFGE and MLVA produced highly concordant results when assigning genotypes to nosocomial VREF isolates. MLVA was faster, but PFGE subtyping was more discriminatory.