Sex differences in associations between creatinine and cystatin C-based kidney function measures with stroke and major bleeding.

PURPOSE: We sought to explore whether adding kidney function biomarkers based on creatinine (eGFRCr), cystatin C (eGFRCys) or a combination of the two (eGFRCr-Cys) could improve risk stratification for stroke and major bleeding, and whether there were sex differences in any additive value of kidney function biomarkers. METHOD: We included participants from the UK Biobank who had not had a previous ischaemic or haemorrhagic stroke or major bleeding episode, and who had kidney function measures available at baseline. Cause-specific Cox proportional hazards models tested associations between eGFRCr, eGFRCys and eGFRCr-Cys (mL/min/1.73 m2) with ischaemic and haemorrhagic stroke, major bleeding (gastrointestinal or intracranial, including haemorrhagic stroke) and all-cause mortality. FINDINGS: Among 452,879 eligible participants, 246,244 (54.4%) were women. Over 11.5 (IQR 10.8-12.2) years, there were 3706 ischaemic strokes, 795 haemorrhagic strokes, 26,025 major bleeding events and 28,851 deaths. eGFRCys was more strongly associated with ischaemic stroke than eGFRCr: an effect that was more pronounced in women (men - HR: 1.16, 95% CI: 1.12-1.19; female to male comparison - HR: 1.11, 95% CI: 1.05-1.16, per 10 mL/min/1.73 m2 decline in eGFRCys). This interaction effect was also demonstrated for eGFRCr-Cys, but not eGFRCr. eGFRCys and eGFRCr-Cys were more strongly associated with major bleeding and all-cause mortality than eGFRCr in both men and women. Event numbers were small for haemorrhagic stroke. DISCUSSION: To a greater degree than is seen in men, eGFRCr underestimates risk of ischaemic stroke and major bleeding in women compared to eGFRCys. The difference between measures is likely explained by non-GFR biology of creatinine and cystatin C. CONCLUSION: Enhanced measurement of cystatin C may improve risk stratification for ischaemic stroke and major bleeding and clinical treatment decisions in a general population setting, particularly for women.

Cost-effectiveness of Interventions to Increase Utilization of Kidneys From Deceased Donors With Primary Brain Malignancy in an Australian Setting.

Kidneys from potential deceased donors with brain cancer are often foregone due to concerns of cancer transmission risk to recipients. There may be uncertainty around donors' medical history and their absolute transmission risk or risk-averse decision-making among clinicians. However, brain cancer transmissions are rare, and prolonging waiting time for recipients is harmful. Methods: We assessed the cost-effectiveness of increasing utilization of potential deceased donors with brain cancer using a Markov model simulation of 1500 patients waitlisted for a kidney transplant, based on linked transplant registry data and with a payer perspective (Australian government). We estimated costs and quality-adjusted life-years (QALYs) for three interventions: decision support for clinicians in assessing donor risk, improved cancer classification accuracy with real-time data-linkage to hospital records and cancer registries, and increased risk tolerance to allow intermediate-risk donors (up to 6.4% potential transmission risk). Results: Compared with current practice, decision support provided 0.3% more donors with an average transmission risk of 2%. Real-time data-linkage provided 0.6% more donors (1.1% average transmission risk) and increasing risk tolerance (accepting intermediate-risk 6.4%) provided 2.1% more donors (4.9% average transmission risk). Interventions were dominant (improved QALYs and saved costs) in 78%, 80%, and 87% of simulations, respectively. The largest benefit was from increasing risk tolerance (mean +18.6 QALYs and AU$2.2 million [US$1.6 million] cost-savings). Conclusions: Despite the additional risk of cancer transmission, accepting intermediate-risk donors with brain cancer is likely to increase the number of donor kidneys available for transplant, improve patient outcomes, and reduce overall healthcare expenditure.

Potential organ donors with primary brain tumours: missed opportunities for donation and transplantation identified in Australian cohort study 2010-2015.

BACKGROUND: Potential organ donors with primary brain tumours (PBT) frequently donate, however some may be declined due to uncertainty about tumour classification or transmission risk to transplant recipients. We sought to describe transmission risk and donation outcome of potential donors with PBT, including identifying missed opportunities for transplantation, and any PBT transmission events. METHODS: We undertook a population-based cohort study in NSW of all potential donors 2010-2015. PBT potential donors were characterized according to tumour grade and transmission risk, and whether they donated organs. Data linkage was used to determine agreement of risk assessment of potential donors to that in the Biovigilance Register, and to identify any PBT transmissions. RESULTS: Of 2957 potential donors, 76 (3%) had PBTs. There was agreement of risk assessment in 44 (58%) cases. PBT potential donors had fewer comorbidities (1.6 vs. 2.1, P = 0.006) than non-PBT potential donors. Forty-eight (63%) potential donors were declined for non-PBT reasons, 18 (24%) were declined because of perceived PBT transmission risk and 10 (13%) donated. All PBT donors had WHO-I or -II tumours, and none had a ventriculo-pertioneal shunt. No transmission events occurred. CONCLUSION: Donors with WHO-I/II PBT appear to have minimal risk of tumour transmission in solid organ transplantation; it is reassuring that no PBT transmission occurred. There is evidence of risk aversion to referrals with WHO-III/IV tumours. There exists opportunity to improve potential donor risk assessment at the time of referral using integrated data sets, and to increase organ donation and transplantation rates through greater utilization of PBT referrals.

Notifiable Infectious Diseases Among Organ Transplant Recipients: A Data-Linked Cohort Study, 2000-2015.

Background: Infections, including common communicable infections such as influenza, frequently cause disease after organ transplantation, although the quantitative extent of infection and disease remains uncertain. Methods: A cohort study was conducted to define the burden of notifiable infectious diseases among all solid organ recipients transplanted in New South Wales, Australia, 2000-2015. Data linkage was used to connect transplant registers to hospital admissions, notifiable diseases, and the death register. Standardized incidence ratios (SIRs) were calculated relative to general population notification rates, accounting for age, sex, and calendar year. Infection-related hospitalizations and deaths were identified. Results: Among 4858 solid organ recipients followed for 39 183 person-years (PY), there were 792 notifications. Influenza was the most common infection (532 cases; incidence, 1358 [95% CI, 1247-1478] per 100 000 PY), highest within 3 months posttransplant. Next most common was salmonellosis (46 cases; incidence, 117 [95% CI, 87-156] per 100 000 PY), then pertussis (38 cases; incidence, 97 [95% CI, 71-133] per 100 000 PY). Influenza and invasive pneumococcal disease (IPD) showed significant excess cases compared with the general population (influenza SIR, 8.5 [95% CI, 7.8-9.2]; IPD SIR, 9.8 [95% CI, 6.9-13.9]), with high hospitalization rates (47% influenza cases, 68% IPD cases) and some mortality (4 influenza and 1 IPD deaths). By 10 years posttransplant, cumulative incidence of any vaccine-preventable disease was 12%, generally similar by transplanted organ, except higher among lung recipients. Gastrointestinal diseases, tuberculosis, and legionellosis had excess cases among transplant recipients, although there were few sexually transmitted infections and vector-borne diseases. Conclusions: There is potential to avoid preventable infections among transplant recipients with improved vaccination programs, health education, and pretransplant donor and recipient screening.

Cancer Mortality in People Receiving Dialysis for Kidney Failure: An Australian and New Zealand Cohort Study, 1980-2013.

RATIONALE & OBJECTIVE: Cancer is a significant cause of morbidity in the population with kidney failure; however, cancer mortality in people undergoing dialysis has not been well described. We sought to compare cancer mortality in people on dialysis for kidney failure with cancer mortality in the general population. STUDY DESIGN: A retrospective cohort study using linked health-administrative and dialysis registry data. SETTING & PARTICIPANTS: All people receiving dialysis represented in the Australian and New Zealand Dialysis and Transplantation Registry, 1980-2013. EXPOSURE: Dialysis; hemodialysis (HD) and peritoneal dialysis (PD). OUTCOME: Death and underlying cause of death ascertained using health administrative data and classified using International Classification of Diseases, Tenth Revision, Australian Modification (ICD-10-AM) codes. ANALYTICAL APPROACH: Indirect standardization on age at death, sex, year, and country to estimate standardized mortality ratios (SMR). RESULTS: Over 269,598 person years of observation, 34,100 deaths occurred among 59,648 people on dialysis, including 3,677 cancer deaths. The relative risk of all-site cancer death in dialysis was twice (SMR, 2.4 [95% CI, 2.33-2.49]) that of the general population and highest for oral and pharynx cancers (SMR, 24.3 [95% CI, 18.0-31.5]) and multiple myeloma (SMR, 22.5 [95% CI, 20.3-23.9]). Women on dialysis had a significantly higher risk of all-site cancer mortality (SMR, 2.7 [95% CI, 2.59-2.89]) compared with men (SMR, 2.3 [95% CI, 2.17-2.36]) (P < 0.001). People on HD (SMR, 2.2 [95% CI, 2.11-2.30]) experienced greater excess deaths from all-site cancer compared with people on PD (SMR, 1.3 [95% CI, 1.23-1.44]). Excess deaths have gradually decreased over time for all-site, multiple myeloma, and kidney cancers (P < 0.001) but have not kept up with improvements in the general population. By contrast, among people receiving dialysis, excess deaths increased for colorectal and lung cancers (P < 0.001). LIMITATIONS: Confirmation of cancer diagnoses and population incidence data were not available; inability to exclude pre-existing cancers. CONCLUSIONS: People on dialysis experience excess all-site and site-specific cancer mortality compared with the general population. Mortality differs by modality type, age, and sex. Understanding the role of kidney failure and other morbidities in the treatment of cancer is important for shared decision-making regarding cancer treatments and identifying potential approaches to improve outcomes.

Perceived Versus Verified Cancer History and Missed Opportunities for Donation in an Australian Cohort of Potential Deceased Solid Organ Donors.

BACKGROUND: There is an imperative to maximize donation opportunities given ongoing organ shortages, but donor suitability assessments can be challenging. METHODS: We analyzed an Australian cohort of potential deceased donors 2010 to 2013 to explore misclassification of cancer risk and potential strategies for improvement (decision support, real-time data linkage to existing data sets, and increasing risk tolerance). Cancer history perceived at referral was compared with verified cancer history in linked health records. Transmission risks were based on clinical guidelines. Potential donors declined due to cancer but verified low risk were missed opportunities; those accepted but verified high risk were excess-risk donors. RESULTS: Among 472 potentially suitable donor referrals, 132 (28%) were declined because of perceived transmission risk and 340 (72%) donated. Assuming a low-risk threshold, there were 38/132 (29%) missed opportunities and 5/340 (1%) excess-risk donors. With decision support, there would have been 5 (13%) fewer missed opportunities and 2 (40%) more excess-risk donors; with real-time data linkage, 6 (16%) fewer missed opportunities and 2 (40%) fewer excess-risk donors; and with increased risk tolerance, 6 (16%) fewer missed opportunities and 11 (220%) more excess-risk donors. CONCLUSIONS: Potential donors' cancer history is typically incomplete at referral. There are missed opportunities where decision support or more accurate cancer history could safely increase organ donors.

Characteristics and Donation Outcomes of Potential Organ Donors Perceived to Be at Increased Risk for Blood-borne Virus Transmission: An Australian Cohort Study 2010-2018.

BACKGROUND: Safely increasing organ donation to meet need is a priority. Potential donors may be declined because of perceived blood-borne virus (BBV) transmission risk. With hepatitis C (HCV) curative therapy, more potential donors may now be suitable. We sought to describe potential deceased donors with increased BBV transmission risk. METHODS: We conducted a cohort study of all potential organ donors referred in NSW, Australia, 2010-2018. We compared baseline risk potential donors to potential donors with increased BBV transmission risk, due to history of HIV, HCV or hepatitis B, and/or behavioral risk factors. RESULTS: There were 624 of 5749 potential donors (10.9%) perceived to have increased BBV transmission risk. This included 298 of 5749 (5.2%) with HCV (including HBV coinfections) and 239 of 5749 (4.2%) with increased risk behaviors (no known BBV). Potential donors with HCV and those with increased risk behaviors were younger and had fewer comorbidities than baseline risk potential donors (P < 0.001). Many potential donors (82 with HCV, 38 with risk behaviors) were declined for donation purely because of perceived BBV transmission risk. Most were excluded before BBV testing. When potential donors with HCV did donate, they donated fewer organs than baseline risk donors (median 1 versus 3, P < 0.01), especially kidneys (odds ratio 0.08, P < 0.001) and lungs (odds ratio 0.11, P = 0.006). CONCLUSIONS: Many potential donors were not accepted because of perceived increased BBV transmission risk, without viral testing, and despite otherwise favorable characteristics. Transplantation could be increased from potential donors with HCV and/or increased risk behaviors.

Prevalence of anal cytological abnormalities and high-risk human papillomavirus prevalence in kidney transplant recipients: A cross-sectional study.

BACKGROUND: Transplant recipients are at high-risk of anal squamous cell cancer. We aimed to estimate the prevalence of high-risk human papillomavirus (HPV) and high-grade squamous intraepithelial lesion (HSIL) and assess characteristics associated with results METHODS: We recruited kidney transplant recipients in a single-center, 2015-2018. Participants completed a clinical questionnaire and received an anal-swab sent for HPV-DNA and cytological testing RESULTS: A total of 97 (74%) of 125 recipients approached consented to participate. Participants were median 47 (IQR 40-55) years, 60% male and median 4.5 (IQR .9-13) months-since-transplant. Of 86 assessable samples, at least one HPV genotype was detected in 15 (17%) participants; 1 (1%) HPV16, 8 (9%) other high-risk HPV. Of 76 assessable cytology samples, 9 (12%) showed evidence of abnormality; 1 (1%) HSIL, 1 (1%) atypical-squamous-cells, cannot exclude HSIL. Both HSIL recipients had high-risk HPV and biopsy confirmed HSIL. High-risk HPV was detected in six (9%) recipients with normal cytology. History of sexually transmitted infection, and abnormal cervical pap smear in women, was associated with high-risk HPV and HSIL CONCLUSIONS: High-risk HPV and HSIL testing may identify kidney transplant recipients at higher risk of anal cancer. Longitudinal studies are needed to describe the natural history of anal cancer in transplant recipients.

Cancer transmissions and non-transmissions from solid organ transplantation in an Australian cohort of deceased and living organ donors.

Evidence on cancer transmission from organ transplantation is poor. We sought to identify cases of cancer transmission or non-transmission from transplantation in an Australian cohort of donors and recipients. We included NSW solid organ deceased donors 2000-2012 and living donors 2004-2012 in a retrospective cohort using linked data from the NSW Biovigilance Register (SAFEBOD). Central Cancer Registry (CCR) data 1972-2013 provided a minimum one-year post-transplant follow-up. We identified cancers in donors and recipients. For each donor-recipient pair, the transmission was judged likely, possible, unlikely, or excluded using categorization from international guidelines. In our analysis, transmissions included those judged likely, while those judged possible, unlikely, or excluded were non-transmissions. In our cohort, there were 2502 recipients and 1431 donors (715 deceased, 716 living). There were 2544 transplant procedures, including 1828 (72%) deceased and 716 (28%) living donor transplants. Among 1431 donors, 38 (3%) had past or current cancer and they donated to 68 recipients (median 6.7-year follow-up). There were 64 (94%) non-transmissions, and 4 (6%) transmissions from two living and two deceased donors (all kidney cancers discovered during organ recovery). Donor transmitted cancers are rare, and selected donors with a past or current cancer may be safe for transplantation.

New blood-borne virus infections among organ transplant recipients: An Australian data-linked cohort study examining donor transmissions and other HIV, hepatitis C and hepatitis B notifications, 2000-2015.

BACKGROUND: Blood-borne viral infections can complicate organ transplantation. Systematic monitoring to distinguish donor-transmitted infections from other new infections post transplant is challenging. Administrative health data can be informative. We aimed to quantify post-transplant viral infections, specifically those transmitted by donors and those reactivating or arising new in recipients. METHODS: We linked transplant registries with administrative health data for all solid organ donor-recipient pairs in New South Wales, Australia, 2000-2015. All new recipient notifications of hepatitis B (HBV), C (HCV), or human immunodeficiency virus (HIV) after transplant were identified. Proven/probable donor transmissions within 12 months of transplant were classified using an international algorithm. RESULTS: Of 2120 organ donors, there were 72 with a viral infection (9/72 active, 63/72 past). These 72 donors donated to 173 recipients, of whom 24/173 already had the same infection as their donor, and 149/173 did not, so were at risk of donor transmission. Among those at risk, 3/149 recipients had proven/probable viral transmissions (1 HCV, 2 HBV); none were unrecognized by donation services. There were no deaths from transmissions. There were no donor transmissions from donors without known blood-borne viruses. An additional 68 recipients had new virus notifications, of whom 2/68 died, due to HBV infection. CONCLUSION: This work confirms the safety of organ donation in an Australian cohort, with no unrecognized viral transmissions and most donors with viral infections not transmitting the virus. This may support targeted increases in donation from donors with viral infections. However, other new virus notifications post transplant were substantial and are preventable. Data linkage can enhance current biovigilance systems.

Effect of language and country of birth on the consent process and medical suitability of potential organ donors; a linked-data cohort study 2010-2015.

PURPOSE: Australia has unmet need for transplantation. We sought to assess the impact of cultural and linguistic diversity (CALD) on family consent and medical suitability for organ donation. METHOD: Cohort study of New South Wales donor referrals, 2010-2015. Logistic regression estimated effects of primary language other than English and birthplace outside Australia (odds ratios OR, with 95% confidence intervals, 95%CI). Outcomes were whether families were asked for consent to donation, provided consent for donation, and whether the referral was medically suitable for donation. RESULTS: Of 2977 organ donor referrals, a similar proportion of families had consent for donation was sought between non-English speakers and English speakers (p = .07), and between overseas-born compared to Australian-born referrals (p = .3). However, consent was less likely to be given for both non-English speakers than English speakers (OR 0.44, 95%CI:0.29-0.67), and those overseas-born than Australian-born (OR 0.54, 95%CI:0.41-0.72). For referrals both overseas-born and non-English speaking, families were both less likely to be asked for consent (OR 0.67; 95%CI:0.49-0.91) or give consent (OR 0.24; 95%CI0.16-0.37). There was no difference in medical suitability between English speakers and non-English speakers (p = .6), or between Australian-born and overseas-born referrals (p = .6). CONCLUSION: Intervention to improve consent rates from CALD families may increase donation.

Cancer mortality in kidney transplant recipients: An Australian and New Zealand population-based cohort study, 1980-2013.

Cancer burden is increasing in kidney transplant recipients, but differences in mortality compared to the general population remain unclear. We sought to compare cancer mortality in paediatric and adult kidney transplant recipients with the general population and describe any differences, by site, age and sex, country and over time. We included kidney transplant recipients from the Australian and New Zealand Dialysis and Transplantation Registry, 1980-2013. Date of death and underlying cause of death were ascertained by data-linkage and classified using ICD10AM codes. Indirect standardisation was used to estimate standardised mortality ratios (SMR). There were 5,284 deaths in 17,628 kidney transplant recipients over 175,084 person-years of observation, including 1,061 (20%) cancer deaths. Relative cancer mortality was higher than the general population for all-site (SMR 2.9, 95% CI 2.7-3.1) cancer and highest for nonmelanoma skin cancer (SMR 50.9, 95% CI 43.5-59.6) and lymphoma (SMR 42.2, 95% CI 35.3-50.5). Relative cancer mortality decreased with increasing age in men (p < 0.001) and women (p = 0.001) but never reached parity with the general population. Relative mortality did not change with age for skin and lip, or colorectal cancers (p-value >0.1). Only relative colorectal cancer mortality increased over time (p = 0.002). Our study shows cancer mortality in kidney transplant recipients was higher than expected in the general population. The magnitude of excess mortality varied by cancer site, age and sex. Further evidence is needed to identify whether this variation is due to differences at diagnosis or access and effectiveness of cancer treatments in this population.

Epidemiology and Comorbidity Burden of Organ Donor Referrals in Australia: Cohort Study 2010-2015.

Increasing organ donation rates in Australia have been exceeded by a rise in potential donor referrals not proceeding to donate. Referral evaluation is resource-intensive. We sought to characterize organ donor referrals in New South Wales, Australia, and identify predictors of referrals not proceeding to donation. METHODS: We performed a cohort study of NSW Organ and Tissue Donation Service logs 2010-2015, describing the prevalence and impact of comorbidities on referral outcome. Logistic regression was used to identify comorbidities influencing outcome and predict probability of donation. RESULTS: Of 2977 referrals, 669 (22%) donated and 2308 (78%) did not. Despite increasing donation rates, the proportion proceeding to donate declined 2010-2015. Among referrals, the prevalence of all comorbidities except cerebrovascular disease increased and was higher among nondonors. History of cardiac disease, ≥65 years of age, chronic kidney or liver disease, malignancy, and absence of cerebrovascular disease were all significantly (P < 0.01) associated with non donation. Hypertension and diabetes did not significantly impact outcome. Predicted probability of donation varied from <1% to 54% depending on comorbidity burden of the referral. CONCLUSIONS: Comorbidity burden among donor referrals is increasing. The presence of particular comorbidities may significantly impact referral outcome. A better understanding of referral characteristics associated with non donation may improve the efficiency of the referral process in the context of encouraging routine referrals.

Weekend effect: analysing temporal trends in solid organ donation.

BACKGROUND: Research suggests patients treated over weekends experience poorer outcomes. Only one US-based study explored this weekend effect in organ donation, specifically the kidney discard rate. In Australia potential donors are referred to a donation service, and donation proceeds if family consent is granted and the donor is deemed medically suitable to donate. Organ procurement occurs when utilization is almost certain hence discard rates are much lower than in the USA. We aimed to characterize the effect of weekend referral on organ donation in Australia. METHODS: We retrospectively reviewed all New South Wales Organ and Tissue Donation Service logs from 2010 to 2016. Our primary outcome was progression to organ procurement, and secondary outcomes were family consent and meeting medical suitability thresholds. We used logistic regression with random effects adjusting for clustering of referral hospitals. RESULTS: Of 3496 potential donors referred for consideration, 694 (20%) progressed to organ procurement. There were fewer referrals on weekends (average 415 versus 588 for weekdays). However, donation rates were no lower for weekend compared to weekday referrals (adjusted OR 1.17; 95% CI 0.95, 1.44). Family consent (adjusted OR 1.20; 95% CI 1.00, 1.44) and medical suitability (adjusted OR 1.15; 95% CI 0.96, 1.38) were not lower for weekend compared to weekday referrals. Similar results were found for all sensitivity analyses conducted. CONCLUSIONS: In Australia, the donation pathway operates consistently throughout the week, with donation no less likely to proceed on weekends and holidays. This finding contrasts with findings in the USA.

Mutation Analysis of Cell-Free DNA and Single Circulating Tumor Cells in Metastatic Breast Cancer Patients with High Circulating Tumor Cell Counts.

PURPOSE: The purpose of this study was to directly compare mutation profiles in multiple single circulating tumor cells (CTC) and cell-free DNA (cfDNA) isolated from the same blood samples taken from patients with metastatic breast cancer (MBC). We aimed to determine whether cfDNA would reflect the heterogeneity observed in 40 single CTCs. EXPERIMENTAL DESIGN: CTCs were enumerated by CELLSEARCH. CTC count was compared with the quantity of matched cfDNA and serum CA15-3 and alkaline phosphatase (ALP) in 112 patients with MBC. In 5 patients with ≥100 CTCs, multiple individual EpCAM-positive CTCs were isolated by DEPArray and compared with matched cfDNA and primary tumor tissue by targeted next-generation sequencing (NGS) of about 2,200 mutations in 50 cancer genes. RESULTS: In the whole cohort, total cfDNA levels and cell counts (≥5 CTCs) were both significantly associated with overall survival, unlike CA15-3 and ALP. NGS analysis of 40 individual EpCAM-positive CTCs from 5 patients with MBC revealed mutational heterogeneity in PIK3CA, TP53, ESR1, and KRAS genes between individual CTCs. In all 5 patients, cfDNA profiles provided an accurate reflection of mutations seen in individual CTCs. ESR1 and KRAS gene mutations were absent from primary tumor tissue and therefore likely either reflect a minor subclonal mutation or were acquired with disease progression. CONCLUSIONS: Our results demonstrate that cfDNA reflects persisting EpCAM-positive CTCs in patients with high CTC counts and therefore may enable monitoring of the metastatic burden for clinical decision-making. Clin Cancer Res; 23(1); 88-96. ©2016 AACR.

Next Generation Sequencing of Circulating Cell-Free DNA for Evaluating Mutations and Gene Amplification in Metastatic Breast Cancer.

BACKGROUND: Breast cancer tissues are heterogeneous and show diverse somatic mutations and somatic copy number alterations (CNAs). We used a novel targeted next generation sequencing (NGS) panel to examine cell-free DNA (cfDNA) to detect somatic mutations and gene amplification in women with metastatic breast cancer (MBC). METHODS: cfDNA from pretreated patients (n = 42) and 9 healthy controls were compared with matched lymphocyte DNA by NGS, using a custom 158 amplicon panel covering hot-spot mutations and CNAs in 16 genes, with further validation of results by droplet digital PCR. RESULTS: No mutations were identified in cfDNA of healthy controls, whereas exactly half the patients with metastatic breast cancer had at least one mutation or amplification in cfDNA (mean 2, range 1-6) across a total of 13 genes. Longitudinal follow up showed dynamic changes to mutations and gene amplification in cfDNA indicating clonal and subclonal response to treatment that was more dynamic than cancer antigen 15-3 (CA15-3). Interestingly, at the time of blood sampling disease progression was occurring in 7 patients with erb-b2 receptor tyrosine kinase 2 (ERBB2) gene amplification in their cfDNA and 3 of these patients were human epidermal growth factor receptor 2 (HER2) negative at diagnosis, suggesting clonal evolution to a more aggressive phenotype. Lastly, 6 patients harbored estrogen receptor 1 (ESR1) mutations in cfDNA, suggesting resistance to endocrine therapy. Overall 9 of 42 patients (21%) had alterations in cfDNA that could herald a change in treatment. CONCLUSIONS: Targeted NGS of cfDNA has potential for monitoring response to targeted therapies through both mutations and gene amplification, for analysis of dynamic tumor heterogeneity and stratification to targeted therapy.