Nehmat Houssami

University of Sydney, Sydney, New South Wales, Australia

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Publications (169)1081.85 Total impact

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    ABSTRACT: Earlier detection of second breast cancers after primary breast cancer (PBC) treatment improves survival, yet mammography is less accurate in women with prior breast cancer. The purpose of this study was to examine women presenting clinically with second breast cancers after negative surveillance mammography (interval cancers), and to estimate the five-year risk of interval-invasive second cancers for women with varying risk profiles. We evaluated a prospective cohort of 15 114 women with 47 717 surveillance mammograms diagnosed with stage 0-II unilateral PBC from 1996 through 2008 at facilities in the Breast Cancer Surveillance Consortium. We used discrete time survival models to estimate the association between odds of an interval-invasive second breast cancer and candidate predictors, including demographic, PBC, and imaging characteristics. All statistical tests were two-sided. The cumulative incidence of second breast cancers after five years was 54.4 per 1000 women, with 325 surveillance-detected and 138 interval-invasive second breast cancers. The five-year risk of interval-invasive second cancer for women with referent category characteristics was 0.60%. For women with the most and least favorable profiles, the five-year risk ranged from 0.07% to 6.11%. Multivariable modeling identified grade II PBC (odds ratio [OR] = 1.95, 95% confidence interval [CI] = 1.15 to 3.31), treatment with lumpectomy without radiation (OR = 3.27, 95% CI = 1.91 to 5.62), interval PBC presentation (OR = 2.01, 95% CI 1.28 to 3.16), and heterogeneously dense breasts on mammography (OR = 1.54, 95% CI = 1.01 to 2.36) as independent predictors of interval-invasive second breast cancers. PBC diagnosis and treatment characteristics contribute to variation in subsequent-interval second breast cancer risk. Consideration of these factors may be useful in developing tailored post-treatment imaging surveillance plans. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
    CancerSpectrum Knowledge Environment 07/2015; 107(7). DOI:10.1093/jnci/djv109 · 15.16 Impact Factor
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    ABSTRACT: Early assessment of response to neoadjuvant chemotherapy (NAC) for breast cancer allows therapy to be tailored; however, optimal response assessment methods have not been established. We estimated the accuracy of ultrasound (US) to predict pathologic complete response (pCR) using common response criteria and pCR definitions, and estimated incremental accuracy over known prognostic variables. Participants undergoing US after two cycles in the GeparTrio trial randomised to no change in NAC were eligible. US response by World Health Organisation (WHO) criteria (1D or 2D) and Response Evaluation Criteria In Solid Tumors (RECIST) was assessed. Four pCR definitions were applied. Sensitivity (correct prediction of pCR), specificity (correct prediction of no-pCR), and diagnostic odds ratios (DORs) were calculated. Areas under the curve (AUCs) were derived from logistic regression including patient variables with and without US. In 832 patients, DORs decreased as pCR definitions became less stringent (p=0.01). For WHO-2D, DORs were: 4.07 (ypT0,ypN0), 3.75 (ypT0/is,ypN0), 3.14 (ypT0/is,ypN+/-), 2.65 (ypT0/is/1a,ypN+/-). DORs did not differ between US criteria (p=0.60). High sensitivity and lower specificity were found for WHO-2D and RECIST; WHO-1D was highly specific with low sensitivity. Sensitivity was highest for WHO-2D predicting ypT0,ypN0 (sensitivity=81.7% specificity=47.6%; vs. 42.3% and 80.4% for WHO-1D). Adding US to models including patient variables (age, T-stage, histology, subtype) improved AUCs for predicting pCR by 2-3%. In conclusion, US accuracy is highest for predicting ypT0,ypN0, shown to be most prognostic of long term survival. WHO-2D and RECIST maximise sensitivity; WHO-1D maximises specificity. US modestly improves the prediction of pCR by patient characteristics. © 2014 Wiley Periodicals, Inc.
    International Journal of Cancer 06/2015; 136(11). DOI:10.1002/ijc.29323 · 5.01 Impact Factor
  • Nehmat Houssami
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    ABSTRACT: The evidence on digital breast tomosynthesis (DBT), or quasi-3D-mammography, for population breast screening has emerged rapidly: two prospective and several retrospective studies provide convincing evidence that mammography with DBT improves screening detection measures compared with standard mammography. Based on population screening studies (which have used various methodologies), adjunct DBT’s incremental breast cancer detection is in the range of 0.5–2.7/1000 screens, and the absolute false recall reduction attributed to DBT is in the range of 0.8–3.6%. Randomized controlled trials assessing the impact of DBT on interval cancer rates as a surrogate for screening benefit would provide critical evidence to underpin population screening policy and practice, and could be designed to also address existing evidence gaps including cost–effectiveness of DBT.
    Expert Review of Medical Devices 05/2015; DOI:10.1586/17434440.2015.1028362 · 1.78 Impact Factor
  • Alberto Tagliafico, Nehmat Houssami
    Radiology 05/2015; 275(2):618-9. DOI:10.1148/radiol.2015142752 · 6.21 Impact Factor
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    T M Svahn, N Houssami
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    ABSTRACT: Three reconstruction algorithms for digital breast tomosynthesis were compared in this article: filtered back-projection (FBP), iterative adapted FBP and maximum likelihood-convex iterative algorithms. Quality metrics such as signal-difference-to-noise ratio, normalised line-profiles and artefact-spread function were used for evaluation of reconstructed tomosynthesis images. The iterative-based methods offered increased image quality in terms of higher detectability and reduced artefacts, which will be further examined in clinical images. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    Radiation Protection Dosimetry 04/2015; DOI:10.1093/rpd/ncv079 · 0.86 Impact Factor
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    T M Svahn, N Houssami
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    ABSTRACT: Clinical studies using different imaging protocols to perform digital breast tomosynthesis (DBT) were reviewed (2008-14) to assess interpretive accuracy. Descriptive pooled statistics were used to estimate and summarise accuracy measures for each type of imaging protocol in relation to that of two-view full-field digital mammography (FFDM). In studies comparing multiple DBT imaging protocols, a trend of increased performance was often seen when including both the mediolateral oblique and craniocaudal views for DBT alone and even more so for DBT adjunct to FFDM. Overall, the average ΔAUC (%; sd) across studies for stand-alone DBT (relative to FFDM), in one and in two views, were 2.2 (±3.7) and 5.9 (±4.6), and when used together with FFDM, 3.9 (±2.0) and 6.7 (±0.9). With respect to individual studies, improvements in accuracy using DBT were present for different types of imaging protocols although the magnitude of the impact varied between studies, and some studies did not show significant improvements in comparison with FFDM. The most consistent effect of improvement in breast cancer detection was seen across studies for two-view DBT with FFDM. These summary findings may depend on the sampling constraints present in tomosynthesis imaging and on other factors discussed in this paper. In order to investigate these effects more thoroughly and how they might impact outcomes, comparative or randomized-controlled trials are warranted. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    Radiation Protection Dosimetry 04/2015; DOI:10.1093/rpd/ncv078 · 0.86 Impact Factor
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    ABSTRACT: We examined geographic patterns in breast cancer survival over time using population-based data for breast cancer diagnosed between 1987 and 2007 in New South Wales, Australia. We found that five-year relative survival increased during the entire study period. Multivariable analysis indicated that there was little geographic variation in 1992-1996, but in 1997-2001 and 2002-2007 geographic variation was statistically significant (P < 0.01), with women living in rural areas having higher risk of death from breast cancer. The underlying reasons for this widening survival disparity must be identified so that appropriately targeted interventions can be implemented and the disparity reduced. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Breast (Edinburgh, Scotland) 04/2015; DOI:10.1016/j.breast.2015.03.006 · 2.58 Impact Factor
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    ABSTRACT: Preoperative breast magnetic resonance (MR) often generates additional suspicious findings needing further investigations. Targeted breast ultrasound (US) is the standard tool to characterize MR additional lesions. The purpose of this study is to evaluate the potential role of digital breast tomosynthesis (DBT) to characterize MR detected additional findings, unidentified at targeted breast US. This prospective study included women who a) had biopsy-proven, newly diagnosed breast cancers detected at conventional 2D mammography and/or US, referred to breast MR for tumour staging; and b) had DBT if additional MR findings were not detected at targeted ('second look') US. In 520 patients, MR identified 164 (in 114 women, 22 %) additional enhancing lesions. Targeted US identified 114/164 (69.5 %) of these, whereas 50/164 (30.5 %) remained unidentified. DBT identified 32/50 of these cases, increasing the overall characterization of MR detected additional findings to 89.0 % (146/164). Using DBT the identified lesions were significantly more likely to be malignant than benign MR-detected additional lesions (p = 0.04). DBT improves the characterization of additional MR findings not identified at targeted breast US in preoperative breast cancer staging. • Targeted US identified 114 of 164 (69.5 %) additional enhancing lesions at preoperative breast MRI. • DBT identified a further 32 of the 50 lesions unidentified on targeted US. • DBT improved the characterization of additional MR findings for breast cancer staging.
    European Radiology 03/2015; DOI:10.1007/s00330-015-3669-4 · 4.34 Impact Factor
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    ABSTRACT: Background: Mammography screening can reduce breast cancer mortality. However, most women are unaware that inconsequential disease can also be detected by screening, leading to overdiagnosis and overtreatment. We aimed to investigate whether including information about overdetection of breast cancer in a decision aid would help women aged around 50 years to make an informed choice about breast screening. Methods: We did a community-based, parallel-group, randomised controlled trial in New South Wales, Australia, using a random cohort of women aged 48-50 years. Recruitment to the study was done by telephone; women were eligible if they had not had mammography in the past 2 years and did not have a personal or strong family history of breast cancer. With a computer program, we randomly assigned 879 participants to either the intervention decision aid (comprising evidence-based explanatory and quantitative information on overdetection, breast cancer mortality reduction, and false positives) or a control decision aid (including information on breast cancer mortality reduction and false positives). Participants and interviewers were masked to group assignment. The primary outcome was informed choice (defined as adequate knowledge and consistency between attitudes and screening intentions), which we assessed by telephone interview about 3 weeks after random allocation. The primary outcome was analysed in all women who completed the relevant follow-up interview questions fully. This trial is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12613001035718. Findings: Between January, 2014, and July, 2014, 440 women were allocated to the intervention group and 439 were assigned to the control group. 21 women in the intervention group and 20 controls were lost to follow-up; a further ten women assigned to the intervention and 11 controls did not answer all questions on attitudes. Therefore, 409 women in the intervention group and 408 controls were analysed for the primary outcome. 99 (24%) of 409 women in the intervention group made an informed choice compared with 63 (15%) of 408 in the control group (difference 9%, 95% CI 3-14; p=0·0017). Compared with controls, more women in the intervention group met the threshold for adequate overall knowledge (122/419 [29%] vs 71/419 [17%]; difference 12%, 95% CI 6-18; p<0·0001), fewer women expressed positive attitudes towards screening (282/409 [69%] vs 340/408 [83%]; 14%, 9-20; p<0·0001), and fewer women intended to be screened (308/419 [74%] vs 363/419 [87%]; 13%, 8-19; p<0·0001). When conceptual knowledge alone was considered, 203 (50%) of 409 women in the intervention group made an informed choice compared with 79 (19%) of 408 in the control group (p<0·0001). Interpretation: Information on overdetection of breast cancer provided within a decision aid increased the number of women making an informed choice about breast screening. Becoming better informed might mean women are less likely to choose screening. Funding: Australian National Health and Medical Research Council. Copyright © 2015 Elsevier Ltd. All rights reserved.
    The Lancet 02/2015; 385(9978). DOI:10.1016/S0140-6736(15)60123-4 · 45.22 Impact Factor
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    ABSTRACT: We examined how radiation dose levels in digital breast tomosynthesis (DBT) differ from those used in 2-view full-field digital mammography (FFDM). Acquisition parameter settings and information on the average absorbed dose to the glandular tissues within the breasts were reviewed based on clinical studies that evaluated DBT and FFDM. Dose ratios (DDBT/DFFDM) were derived from imaging protocols, which included tomosynthesis in 1- or 2-views alone, and as an adjunct technique to FFDM. Stand-alone DBT was associated with a much lower to a slightly higher radiation dose compared to that of comparable FFDM units, as summarized in dose ratio ranges of 0.34-1.0 for 1-view DBT, and 0.68-1.17 for 2-view DBT. One of the lowest reported dose estimates was obtained using a photon-counting DBT unit (avg. 0.70 mGy/scan; range: 0.28-1.26 mGy). Breast doses for DBT combined with FFDM are summarized in dose ratio ranges of 1.03-1.5 for 1-view DBT plus FFDM, and 2.0-2.23 for 2-view DBT plus FFDM. In the latter of these settings, the dose was reduced by ∼45% when 2D-views, reconstructed from the DBT images ("synthetic 2D images"), were used as a substitute for FFDM. Stand-alone DBT operated at lower to slightly higher radiation doses in comparison to FFDM. For DBT combined with FFDM, radiation doses were elevated, at maximum by a factor ∼2 1/4 of that of FFDM alone. In this setting, a replacement of FFDM with synthetic 2D-views reduced the breast dose approximately by half, which has substantial implications for population screening programs. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Breast (Edinburgh, Scotland) 12/2014; 24(2). DOI:10.1016/j.breast.2014.12.002 · 2.58 Impact Factor
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    ABSTRACT: There is no consensus on whether magnetic resonance imaging (MRI) should be included in breast screening protocols for women with BRCA1/2 mutations age ≥ 50 years. Therefore, we investigated the evidence on age-related screening accuracy in women with BRCA1/2 mutations using individual patient data (IPD) meta-analysis. IPD were pooled from six high-risk screening trials including women with BRCA1/2 mutations who had completed at least one screening round with both MRI and mammography. A generalized linear mixed model with repeated measurements and a random effect of studies estimated sensitivity and specificity of MRI, mammography, and the combination in all women and specifically in those age ≥ 50 years. Pooled analysis showed that in women age ≥ 50 years, screening sensitivity was not different from that in women age < 50 years, whereas screening specificity was. In women age ≥ 50 years, combining MRI and mammography significantly increased screening sensitivity compared with mammography alone (94.1%; 95% CI, 77.7% to 98.7% v 38.1%; 95% CI, 22.4% to 56.7%; P < .001). The combination was not significantly more sensitive than MRI alone (94.1%; 95% CI, 77.7% to 98.7% v 84.4%; 95% CI, 61.8% to 94.8%; P = .28). Combining MRI and mammography in women age ≥ 50 years resulted in sensitivity similar to that in women age < 50 years (94.1%; 95% CI, 77.7% to 98.7% v 93.2%; 95% CI, 79.3% to 98%; P = .79). Addition of MRI to mammography for screening BRCA1/2 mutation carriers age ≥ 50 years improves screening sensitivity by a magnitude similar to that observed in younger women. Limiting screening MRI in BRCA1/2 carriers age ≥ 50 years should be reconsidered. © 2014 by American Society of Clinical Oncology.
    Journal of Clinical Oncology 12/2014; 33(4). DOI:10.1200/JCO.2014.56.6232 · 18.43 Impact Factor
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    ABSTRACT: Background Breast cancer places a heavy burden on the Australian healthcare system, but information about the actual number of women living with breast cancer and their current or future health service needs is limited. We used existing population-based data and innovative statistical methods to address this critical research question in a well-defined geographic region. Methods Breast cancer data from the New South Wales (NSW) Central Cancer Registry and PIAMOD (Prevalence and Incidence Analysis MODel) software were used to project future breast cancer prevalence in NSW. Parametric models were fitted to incidence and survival data, and the modelled incidence and survival estimates were then used to estimate current and future prevalence. To estimate future healthcare requirements the projected prevalence was then divided into phases of care according to the different stages of the survivorship trajectory. Results The number of women in NSW living with a breast cancer diagnosis had increased from 19,305 in 1990 to 48,754 in 2007. This number is projected to increase further to 68,620 by 2017. The majority of these breast cancer survivors will require continued monitoring (31,974) or will be long-term survivors (29,785). About 9% will require active treatment (either initial therapy, or treatment for subsequent metastases or second cancer) and 1% will need end of life care due to breast cancer. Conclusions Extrapolating these projections to the national Australian population would equate to 209,200 women living with breast cancer in Australia in 2017, many of whom will require active treatment or post-treatment monitoring. Thus, careful planning and development of a healthcare system able to respond to this increased demand is required.
    BMC Cancer 12/2014; 2014, 14:936(1):936. DOI:10.1186/1471-2407-14-936 · 3.32 Impact Factor
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    The Breast 09/2014; 23(5):489-502. DOI:10.1016/j.breast.2014.08.009. · 2.58 Impact Factor
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    Annals of Oncology 09/2014; 25(10):871-88. DOI:10.1093/annonc/mdu385 · 6.58 Impact Factor
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    ABSTRACT: To develop, pilot and refine a decision aid (ahead of a randomised trial evaluation) for women around age 50 facing their initial decision about whether to undergo mammography screening.
    BMJ Open 09/2014; 4(9):e006016. DOI:10.1136/bmjopen-2014-006016 · 2.06 Impact Factor
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    ABSTRACT: Objectives To compare DBT and FFDM in the classification of microcalcification clusters (MCs) using BI-RADS. Methods This Institutional Review Board-approved study was undertaken in three centres. A total of 107 MCs evaluated with both DBT and FFDM were randomised for prospective reading by six experienced breast radiologists and classified using BI-RADS. Results The benign/malignant ratio of MC was 66/41. Of 11/107 discordant results, DBT classified MCs as R2 whereas FFDM classified them as R3 in 9 and R4 in 2. Three of these (3/107 = 2.8 %) were malignant; 8 (7.5 %) were nonmalignant and were correctly classified as R2 on DBT but incorrectly classified as R3 on FFDM. Estimated sensitivity and specificity, respectively, were 100 % (95 % CI: 91 % to 100 %) and 94.6 % (95 % CI: 86.7 % to 98.5 %) for FFDM and 91.1 % (95 % CI: 78.8 % to 97.5 %) and 100 % (95 % CI: 94.8 % to 100 %) for DBT. Overall intra- and interobserver agreements were 0.75 (95 % CI: 0.61-0.84) and 0.73 (95 % CI: 0.62-0.78). Conclusions Most MCs are scored similarly on FFDM and DBT. Although a minority (11/107) of MCs are classified differently on FFDM (benign MC classified as R3) and DBT (malignant MC classified as R2), this may have clinical relevance. Key Points • The BI-RADS classification of MC differs for FFDM and DBT in 11/107 cases • DBT assigned lower BI-RADS classes compared to FFDM in 11 clusters • In 4/107 DBT may have missed some malignant and high-risk lesions • In 7/107 the ‘underclassification’ on DBT was correct, potentially avoiding unnecessary biopsies • DBT may miss a small proportion of malignant lesions
    European Radiology 08/2014; 25(1). DOI:10.1007/s00330-014-3402-8 · 4.34 Impact Factor
  • Archives of pathology & laboratory medicine 08/2014; 139(5). DOI:10.5858/arpa.2014-0384-ED · 2.88 Impact Factor
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    ABSTRACT: Debate about the extent of breast cancer over-diagnosis due to mammography screening has continued for over a decade, without consensus. Estimates range from 0-54%, but many studies have been criticized for having flawed methodology. In this study we used a novel study design to estimate over-diagnosis due to organised mammography screening in South Australia (SA). To estimate breast cancer incidence at and following screening we used a population-based, age-matched case-control design involving 4931 breast cancer cases and 22914 controls to obtain OR for yearly time intervals since women’s last screening mammogram. The level of over-diagnosis was estimated by comparing the cumulative breast cancer incidence with and without screening. The former was derived by applying OR for each time window to incidence rates in the absence of screening, and the latter, by projecting pre-screening incidence rates. Sensitivity analyses were undertaken to assess potential biases. Over-diagnosis was estimated to be 8% (95%CI 2-14%) and 14% (95%CI 8-19%) among SA women aged 45-85 years from 2006-2010, for invasive breast cancer and all breast cancer respectively. These estimates were robust when applying various sensitivity analyses, except for adjustment for potential confounding assuming higher risk among screened than non-screened women, which reduced levels of over-diagnosis to 1% (95%CI -5 -7%) and 8% (95%CI 2-14%) respectively when incidence rates for screening participants were adjusted by 10%. Our results indicate that the level of over-diagnosis due to mammography screening is modest and considerably lower than many previous estimates, including other for Australia. © 2014 Wiley Periodicals, Inc.
    International Journal of Cancer 08/2014; 136(6). DOI:10.1002/ijc.29124 · 5.01 Impact Factor
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    ABSTRACT: IntroductionThis study aimed to evaluate the accuracy of radiographers’ screen-reading mammograms. Currently, radiologist workforce shortages may be compromising the BreastScreen Australia screening program goal to detect early breast cancer. The solution to a similar problem in the United Kingdom has successfully encouraged radiographers to take on the role as one of two screen-readers. Prior to consideration of this strategy in Australia, educational and experiential differences between radiographers in the United Kingdom and Australia emphasise the need for an investigation of Australian radiographers’ screen-reading accuracy.Methods Ten radiographers employed by the Westmead Breast Cancer Institute with a range of radiographic (median = 28 years), mammographic (median = 13 years) and BreastScreen (median = 8 years) experience were recruited to blindly and independently screen-read an image test set of 500 mammograms, without formal training. The radiographers indicated the presence of an abnormality using BI-RADS®. Accuracy was determined by comparison with the gold standard of known outcomes of pathology results, interval matching and client 6-year follow-up.ResultsIndividual sensitivity and specificity levels ranged between 76.0% and 92.0%, and 74.8% and 96.2% respectively. Pooled screen-reader accuracy across the radiographers estimated sensitivity as 82.2% and specificity as 89.5%. Areas under the reading operating characteristic curve ranged between 0.842 and 0.923.Conclusions This sample of radiographers in an Australian setting have adequate accuracy levels when screen-reading mammograms. It is expected that with formal screen-reading training, accuracy levels will improve, and with support, radiographers have the potential to be one of the two screen-readers in the BreastScreen Australia program, contributing to timeliness and improved program outcomes.
    08/2014; 62(1). DOI:10.1002/jmrs.59
  • International journal of radiation oncology, biology, physics 08/2014; 89(5):1139–1141. DOI:10.1016/j.ijrobp.2014.04.032 · 4.18 Impact Factor

Publication Stats

4k Citations
1,081.85 Total Impact Points

Institutions

  • 2002–2015
    • University of Sydney
      • School of Public Health
      Sydney, New South Wales, Australia
  • 2005–2009
    • Westmead Hospital
      Sydney, New South Wales, Australia
    • Breast Cancer Prevention Institute
      Somerville, New Jersey, United States
  • 2005–2008
    • Istituto per lo Studio e la Prevenzione Oncologica (ISPO)
      Florens, Tuscany, Italy
  • 2005–2006
    • Westmead Breast Cancer Institute NSW
      Sydney, New South Wales, Australia
  • 1998–2004
    • Sydney Breast Clinic
      Sydney, New South Wales, Australia