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Background There is significant interest in personalised, risk-based breast cancer screening. This requires high quality risk assessment. The ‘Gail model’ risk assessment tool has been validated on over 40,000 BreastScreen Australia participants. We assess whether adding mammographic density (MD) information improves risk stratification on that cohort. Methods We used questionnaire data, baseline MD readings (using AutoDensity) and linked screening and cancer registry records from 40,158 BreastScreen Australia participants aged 50–69 years (via the lifepool cohort). We investigated incident invasive breast cancer rates by quintiles of Gail model scores, MD, and combinations of Gail and MD. Results Gail scores and MD values were weakly correlated (r≤0.02). Gail and MD were each strong predictors of incident breast cancer, but stronger predictors when used in combination. For example, the odds ratio for incident invasive breast cancer was 3.6 (95%CI 2.5-6.3) for the 17% of women in the upper two quintiles of both Gail and MD scores compared to the 17% of women in the lower two quintiles of both scores. In comparison, the odds ratio for breast cancer between same-size (each 17%) upper and lower groups for Gail score alone was 2.5 (95%CI 1.8-3.4), and for MD 1.9 (95%CI 1.2-2.9). Conclusions Combining Gail and MD categories improves risk stratification on BreastScreen Australia participants, compared to using Gail or MD alone. Key messages While questionnaire data and MD measures are each strong predictors of future invasive breast cancer among BreastScreen Australia participants, risk prediction is stronger when questionnaire and MD measures are combined.

Breast cancer (BC) diagnosed after a negative mammogram but prior to the next screening episode is termed an 'interval BC' (IBC). Understanding the molecular differences between IBC and screen-detected BCs (SDBC) could improve mammographic screening and management options. Therefore, we assessed both germline and somatic genomic aberrations in a prospective cohort. Utilising the Lifepool cohort of >54 000 women attending mammographic screening programs, 930 BC cases with screening status were identified (726 SDBC and 204 IBC). Clinico-pathological and family history information were recorded. Germline and tumour DNA were collected where available and sequenced for BC predisposition and driver gene mutations. Compared to SDBC, IBCs were significantly associated with a younger age at diagnosis and tumour characteristics associated with worse prognosis. Germline DNA assessment of BC cases that developed post-enrolment (276 SDBCs and 77 IBCs) for pathogenic mutations in 12 hereditary BC predisposition genes identified 8 carriers (2.27%). The germline mutation frequency was higher in IBC versus SDBC, although not statistically significant (3.90% versus 1.81%, p = 0.174). Comparing somatic genetic features of IBC and SDBC matched for grade, histological subtype and hormone receptor revealed no significant differences, with the exception of higher homologous recombination deficiency scores in IBC, and copy number changes on chromosome Xq in triple negative SDBCs. Our data demonstrates that while IBCs are clinically more aggressive than SDBC, when matched for confounding clinico-pathological features they do not represent a unique molecular class of invasive BC, but could be a consequence of timing of tumour initiation and mammographic screening. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Findings 5585 families with Lynch syndrome from 22 countries were eligible for the analysis. Of these, there were insufficient numbers to estimate penetrance for Asia and South America, and for those with EPCAM variants. Therefore, we used data (collected between July 11, 2014, and Dec 31, 2018) from 5255 families (1829 MLH1, 2179 MSH2, 798 MSH6, and 449 PMS2), comprising 79 809 relatives, recruited in 15 countries in North America, Europe, and Australasia. There was strong evidence of the existence of unknown familial risk factors modifying colorectal cancer risk for Lynch syndrome carriers (p 0 center dot 0001 for each of the three three continents). These familial risk factors resulted in a wide within-gene variation in the risk of colorectal cancer for men and women from each continent who all carried pathogenic variants in the same gene or the MSH2 c.942+3A T variant. The variation was especially prominent for MLH1 and MSH2 variant carriers, depending on gene, sex and continent, with 7-56% of carriers having a colorectal cancer penetrance of less than 20%, 9-44% having a penetrance of more than 80%, and onlyBackground Existing clinical practice guidelines for carriers of pathogenic variants of DNA mismatch repair genes (Lynch syndrome) are based on the mean age-specific cumulative risk (penetrance) of colorectal cancer for all carriers of pathogenic variants in the same gene. We aimed to estimate the variation in the penetrance of colorectal cancer between carriers of pathogenic variants in the same gene by sex and continent of residence. Methods In this retrospective cohort study, we sourced data from the International Mismatch Repair Consortium, which comprises 273 members from 122 research centres or clinics in 32 countries from six continents who are involved in Lynch syndrome research. Families with at least three members and at least one confirmed carrier of a pathogenic or likely pathogenic variant in a DNA mismatch repair gene (MLH1, MSH2, MSH6, or PMS2) were included. The families of probands with known de-novo pathogenic variants were excluded. Data were collected on the method of ascertainment of the family, sex, carrier status, cancer diagnoses, and ages at the time of pedigree collection and at last contact or death. We used a segregation analysis conditioned on ascertainment to estimate the mean penetrance of colorectal cancer and modelled unmeasured polygenic factors to estimate the variation in penetrance. The existence of unknown familial risk factors modifying colorectal cancer risk for Lynch syndrome carriers was tested by use of a Wald p value for the null hypothesis that the polygenic SD is zero. Findings 5585 families with Lynch syndrome from 22 countries were eligible for the analysis. Of these, there were insufficient numbers to estimate penetrance for Asia and South America, and for those with EPCAM variants. Therefore, we used data (collected between July 11, 2014, and Dec 31, 2018) from 5255 families (1829 MLH1, 2179 MSH2, 798 MSH6, and 449 PMS2), comprising 79 809 relatives, recruited in 15 countries in North America, Europe, and Australasia. There was strong evidence of the existence of unknown familial risk factors modifying colorectal cancer risk for Lynch syndrome carriers (pT variant. The variation was especially prominent for MLH1 and MSH2 variant carriers, depending on gene, sex and continent, with 7-56% of carriers having a colorectal cancer penetrance of less than 20%, 9-44% having a penetrance of more than 80%, and only 10-19% having a penetrance of 40-60%. Interpretation Our study findings highlight the important role of risk modifiers, which could lead to personalised risk assessments for precision prevention and early detection of colorectal cancer for people with Lynch syndrome. Funding National Health and Medical Research Council, Australia. Copyright (c) 2021 Elsevier Ltd. All rights reserved.Methods In this retrospective cohort study, we sourced data from the International Mismatch Repair Consortium, which comprises 273 members from 122 research centres or clinics in 32 countries from six continents who are involved in Lynch syndrome research. Families with at least three members and at least one confirmed carrier of a pathogenic or likely pathogenic variant in a DNA mismatch repair gene (MLH1, MSH2, MSH6, or PMS2) were included. The families of probands with known de-novo pathogenic variants were excluded. Data were collected on the method of ascertainment of the family, sex, carrier status, cancer diagnoses, and ages at the time of pedigree collection and at last contact or death. We used a segregation analysis conditioned on ascertainment to estimate the mean penetrance of colorectal cancer and modelled unmeasured polygenic factors to estimate the variation in penetrance. The existence of unknown familial risk factors modifying colorectal cancer risk for Lynch syndrome carriers was tested by use of a Wald p value for the null hypothesis that the polygenic SD is zero.

Mammographic density (MD) influences breast cancer risk, but how this is mediated is unknown. Molecular differences between breast cancers arising in the context of the lowest and highest quintiles of mammographic density may identify the mechanism through which MD drives breast cancer development. Women diagnosed with invasive or in situ breast cancer where MD measurement was also available (n = 842) were identified from the Lifepool cohort of >54,000 women participating in population-based mammographic screening. This group included 142 carcinomas in the lowest quintile of MD and 119 carcinomas in the highest quintile. Clinico-pathological and family history information were recorded. Tumor DNA was collected where available (n = 56) and sequenced for breast cancer predisposition and driver gene mutations, including copy number alterations. Compared to carcinomas from low-MD breasts, those from high-MD breasts were significantly associated with a younger age at diagnosis and features associated with poor prognosis. Low- and high-MD carcinomas matched for grade, histological subtype, and hormone receptor status were compared for somatic genetic features. Low-MD carcinomas had a significantly increased frequency of TP53 mutations, higher homologous recombination deficiency, higher fraction of the genome altered, and more copy number gains on chromosome 1q and losses on 17p. While high-MD carcinomas showed enrichment of tumor-infiltrating lymphocytes in the stroma. The data demonstrate that when tumors were matched for confounding clinico-pathological features, a proportion in the lowest quintile of MD appear biologically distinct, reflective of microenvironment differences between the lowest and highest quintiles of MD.

IntroductionFor women of the same age and body mass index, increased mammographic density is one of the strongest predictors of breast cancer risk. There are multiple methods of measuring mammographic density and other features in a mammogram that could potentially be used in a screening setting to identify and target women at high risk of developing breast cancer. However, it is unclear which measurement method provides the strongest predictor of breast cancer risk.Methods and analysisThe measurement challenge has been established as an international resource to offer a common set of anonymised mammogram images for measurement and analysis. To date, full field digital mammogram images and core data from 1650 cases and 1929 controls from five countries have been collated. The measurement challenge is an ongoing collaboration and we are continuing to expand the resource to include additional image sets across different populations (from contributors) and to compare additional measurement methods (by challengers). The intended use of the measurement challenge resource is for refinement and validation of new and existing mammographic measurement methods. The measurement challenge resource provides a standardised dataset of mammographic images and core data that enables investigators to directly compare methods of measuring mammographic density or other mammographic features in case/control sets of both raw and processed images, for the purposes of the comparing their predictions of breast cancer risk.Ethics and disseminationChallengers and contributors are required to enter a Research Collaboration Agreement with the University of Melbourne prior to participation in the measurement challenge. The Challenge database of collated data and images are stored in a secure data repository at the University of Melbourne. Ethics approval for the measurement challenge is held at University of Melbourne (HREC ID 0931343.3).

Background There is a growing interest in delivering more personalised, risk-based breast cancer screening protocols. This requires population-level validation of practical models that can stratify women into breast cancer risk groups. Few studies have evaluated the Gail model (NCI Breast Cancer Risk Assessment Tool) in a population screening setting; we validated this tool in a large, screened population. Methods We used data from 40,158 women aged 50–69 years (via the lifepool cohort) participating in Australia’s BreastScreen programme. We investigated the association between Gail scores and future invasive breast cancer, comparing observed and expected outcomes by Gail score ranked groups. We also used machine learning to rank Gail model input variables by importance and then assessed the incremental benefit in risk prediction obtained by adding variables in order of diminishing importance. Results Over a median of 4.3 years, the Gail model predicted 612 invasive breast cancers compared with 564 observed cancers (expected/observed (E/O) = 1.09, 95% confidence interval (CI) 1.00–1.18). There was good agreement across decile groups of Gail scores (χ2 = 7.1, p = 0.6) although there was some overestimation of cancer risk in the top decile of our study group (E/O = 1.65, 95% CI 1.33–2.07). Women in the highest quintile (Q5) of Gail scores had a 2.28-fold increased risk of breast cancer (95% CI 1.73–3.02, p

Background Vancomycin has historically been the mainstay of therapy for MRSA bacteremia, but severe infections due to vancomycin-intermediate Staphylococcus aureus have emerged. In vitro studies have shown that the combination of a β-lactam antibiotic, such as ceftaroline with daptomycin, was synergistic against MRSA. The purpose of this study was to compare outcomes in patients who received daptomycin and ceftaroline in combination vs. vancomycin for the treatment of MRSA bacteremia. Methods This was a retrospective exploratory cohort study approved by the institutional review board at Cooper University Hospital. Patients were included if they received daptomycin/ceftaroline (cases) or vancomycin (controls) for the treatment of MRSA bacteremia between November 2010 and March 2017. Cases were matched 1:1 with controls based on source of MRSA bacteremia, age within 10 years, and renal function. The primary endpoint was clinical cure, defined as the improvement of signs and symptoms of bacteremia. Secondary endpoints included microbiologic cure, time to sterilization of blood cultures, duration of hospital stay, overall mortality, and MRSA-related mortality. Results Forty-one cases were included. There was no statistical difference between the two groups in microbiologic cure, time to sterilization of blood cultures, overall mortality, or MRSA-related mortality. There were no significant differences between patients in each group including in those with ICU admissions and who required vasopressors. Cases were significantly more likely to have hardware compared with the control group (43.9% vs. 12.2%; P = 0.0014). Clinical cure was achieved in 27 patients (65.9%) in the case group and 26 patients (63.4%) in the control group (P = 0.8173). Patients in the case group had a statistically longer mean hospital duration (29 days vs. 21 days, respectively, P = 0.0206) and more secondary complications such as bone infection (P = 0.0076). Conclusion Time to sterilization of blood cultures and overall mortality were similar in both groups. Patients in the combination group had longer hospital stays compared with vancomycin monotherapy. Daptomycin/ceftaroline combination therapy is an option for complicated MRSA bacteremia. Larger studies should be conducted to further evaluate this combination. Disclosures All authors: No reported disclosures.

Aims: The International Mismatch Repair Consortium (IMRC) was formed in 2010 and comprises major worldwide consortia involved in the research and/or clinical treatment of Lynch syndrome (cancer predisposition caused by inherited mutations in mismatch repair (MMR) genes: MLH1, MSH2, MSH6, PMS2 and EPCAM); http://www.sphinx.org.au/imrc. The aim of this study was to determine cancer risks by geographic region. Methods: For each cancer, we estimated the age-specific cumulative risks (penetrance) and the hazard ratios compared to the average population risk. We used a modified segregation analysis and adjusted for any ascertainment of families given this is an analysis of prospective data. We estimated penetrance by: cancer sex, mismatch repair gene, type of mutation, and geographic region. Results: 43 investigators representing 53 different sites in 23 countries have submitted pedigree data. In total IMRC consists of 6,436 Lynch syndrome families (North America = 2,482, South America = 101, Europe = 3,307, Asia = 216, Australasia = 330). Of these, 2,214 were MLH1, 2,717 were MSH2, 1,118 were MSH6, 558 were PMS2, and 44 were EPCAM. The total number of distinct variants were 1,270 and the maximum size of families was 333 relatives. Of the distinct MMR variants submitted to the IMRC, 89% were classified as Class 4 (likely pathogenic) or 5 (pathogenic) by the InSiGHT Variant classification criteria (LOVD). Penetrance analyses were conducted only for the pathogenic or likely pathogenic variants. Preliminary analyses suggest that the risk of colorectal cancer to age 70 is highest for carriers in Australasia and North America and lowest for carriers in South America and Asia (Table 1). Conclusion: Preliminary results suggest that cancer risks for people with Lynch syndrome differ by geographic region, which is consistent with environmental modifiers for the disease and might justify region-specific screening guidelines. Risk (% to age 70) and hazard ratio (HR) of colorectal cancer by MMR gene and regionGeneRegionHR (95% CI)Risk MalesRisk FemalesMLH1Europe19 (14-26)50%32%MLH1Nth America32 (26-38)61%48%MLH1Australasia32 (22-46)68%55%MLH1Sth America6 (2-22)12%10%MLH1Asia7 (5-15)39%24%MSH2Europe14 (11-16)39%24%MSH2Nth America33 (28-40)61%50%MSH2Australasia36 (24-54)73%59%MSH2Sth America70 (10-490)82%75%MSH2Asia8 (5-17)21%15% Citation Format: Mark A. Jenkins, Jeanette Reece, Grant Lee, Aung K. Win, International Mismatch Repair Consortium. International comparison of cancer risks for Lynch syndrome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1238.

1526Background: Lynch syndrome is a cancer predisposition caused by inherited mutations in mismatch repair genes MLH1, MSH2, MSH6 and PMS2, or EPCAM. Accurate cancer risk estimates are required for...

Background There is debate as to whether deep inguinal lymph nodes should be removed with the superficial or femoral lymph nodes during sentinel lymph node biopsy for lower extremity melanoma, when both superficial and deep inguinal lymph nodes are identified by preoperative lymphoscintigraphy. This study evaluated the lymphatic drainage patterns in lower extremity melanoma to determine whether certain patterns could be used to limit the level of node removal and define the extent of dissection. Methods A retrospective outcomes review was performed of lower extremity melanoma patients with excision and sentinel lymph node biopsy from 1995 to 2010. Outcomes included location of sentinel lymph node drainage basins, sentinel lymph node-positivity, and disease-free and overall survival, with drainage patterns compared between above- and below-knee melanomas. Results Of 499 patients with lower extremity melanoma having sentinel lymph node biopsy, 356 had below-the-knee and 143 had above-the-knee melanoma. For below-knee melanoma, the node-positivity rate was 23 percent (63 of 271) for superficial inguinal, 0 percent (zero of three) for deep inguinal, and 50 percent (one of two) for popliteal basins. For above-knee melanoma, the positivity rate was 21 percent (24 of 113) for superficial inguinal, 33 percent (one of three) for deep inguinal basins, and 0 percent (zero of zero) for popliteal basins. Importantly, no patients with a negative superficial inguinal sentinel lymph node had a positive deep inguinal sentinel lymph node on final pathologic evaluation [corrected]. Conclusions A difference was noted in patterns of sentinel lymph node drainage from lower extremity melanoma below and above the knee. Biopsy for deep inguinal basins may be deferred if there is simultaneous drainage to the superficial inguinal basin by preoperative lymphoscintigraphy. Clinical question/level of evidence Risk, II.