- Pittsburgh, Pennsylvania, United States
Stewart Anderson
University of Pittsburgh, Biostatistics, Faculty Member
Research Interests:
BackgroundBlack race is associated with worse outcome in patients with breast cancer. We evaluated distant relapse-free survival (DRFS) between Black and White women with localized breast cancer who participated in NCI-sponsored clinical... more
BackgroundBlack race is associated with worse outcome in patients with breast cancer. We evaluated distant relapse-free survival (DRFS) between Black and White women with localized breast cancer who participated in NCI-sponsored clinical trials.MethodsWe analyzed pooled data from eight National Surgical Adjuvant Breast and Bowel Project (NSABP) trials including 9,702 women with localized breast cancer treated with adjuvant chemotherapy (AC, n=7,485) or neoadjuvant chemotherapy (NAC, n=2,217), who self-reported as Black (n=1,070) or White (n=8,632). The association between race and DRFS was analyzed using log-rank tests and multivariate Cox regression.ResultsAfter adjustment for covariates including age, tumor size, nodal status, body mass index and taxane use, and treatment (AC vs. NAC), Black race was associated with an inferior DRFS in ER-positive (HR 1.24 [95% CI 1.05-1.46], p=0.01), but not in ER-negative disease (HR 0.97 [95% CI 0.83-1.14], p=0.73), and significant interaction ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Research Design, Psychotherapy, Mental Health, Depression, Medicine, and 14 moreProblem Solving, Population, Humans, Major Depressive Disorder, Female, Male, Clinical Sciences, Aged, Public health systems and services research, Randomized Controlled Trial, Home Care Services, Psychiatric Status Rating Scales, Disability Evaluation, and Patient selection
Bisphosphonates have profound effects on bone physiology, and could modify the process of metastasis. We undertook collaborative meta-analyses to clarify the risks and benefits of adjuvant bisphosphonate treatment in breast cancer. We... more
Bisphosphonates have profound effects on bone physiology, and could modify the process of metastasis. We undertook collaborative meta-analyses to clarify the risks and benefits of adjuvant bisphosphonate treatment in breast cancer. We sought individual patient data from all unconfounded trials in early breast cancer that randomised between bisphosphonate and control. Primary outcomes were recurrence, distant recurrence, and breast cancer mortality. Primary subgroup investigations were site of first distant recurrence (bone or other), menopausal status (postmenopausal [combining natural and artificial] or not), and bisphosphonate class (aminobisphosphonate [eg, zoledronic acid, ibandronate, pamidronate] or other [ie, clodronate]). Intention-to-treat log-rank methods yielded bisphosphonate versus control first-event rate ratios (RRs). We received data on 18,766 women (18,206 [97%] in trials of 2-5 years of bisphosphonate) with median follow-up 5·6 woman-years, 3453 first recurrences, ...
Research Interests:
Gait speed is as an important predictor of mortality, volume of medical care, hospitalization, onset of activities of daily living (ADL) disability, and nursing home placement. We examined associations between change in gait speed and... more
Gait speed is as an important predictor of mortality, volume of medical care, hospitalization, onset of activities of daily living (ADL) disability, and nursing home placement. We examined associations between change in gait speed and change in observed performance in the instrumental ADL (IADL) in a sample of mild-to-moderately disabled older adults. Participants in the Sources of Independence in the Elderly project (n = 375) were approached to complete a 4-m gait assessment and a performance test of IADL competency at three points over 2 years. IADL competency was assessed by occupational therapists, who rated participants using the Assessment of Motor and Process Skills (AMPS) and who also made a global rating of need for help or supervision. Linear mixed models were developed to assess change in motor AMPS score relative to baseline status and change in gait speed and AMPS process scores. Baseline gait and change in gait were significant correlates of change in the AMPS motor ab...
Research Interests: Ergonomics, Human Factors, Cognition, Aging, Injury Prevention, and 15 moreMedicine, Physical Medicine and Rehabilitation, Activities of Daily Living, Gait, Humans, New York City, Female, Male, Clinical Sciences, Aged, Occupational Safety, Geriatric Assessment, Motor Skills, Disabled Persons, and Disability Evaluation
Research Interests: Oncology, Evidence Based Medicine, Breast Cancer, Survival Analysis, Medicine, and 15 moreProspective studies, Humans, Internal Medicine, Female, Clinical Sciences, Aged, Middle Aged, Adult, Randomized Controlled Trial, Odds ratio, Prognosis, Lumpectomy, Cumulative Incidence, Breast Neoplasms, and hazard ratio
Research Interests:
Research Interests: Oncology, Breast Cancer, Medicine, England, Occult, and 15 moreHumans, Female, Clinical Sciences, Middle Aged, Prognosis, Axilla, Cohort Studies, Lymph nodes, Breast Neoplasms, Disease Free Survival, Treatment Failure, Sentinel lymph node biopsy, Sentinel node, Medical and Health Sciences, and Sentinel Lymph Node
We describe the development of an intervention strategy for the indicated prevention of depression in older adults living in Goa, India. Of particular novelty, the intervention is deliverable by lay health counselors and is grounded in... more
We describe the development of an intervention strategy for the indicated prevention of depression in older adults living in Goa, India. Of particular novelty, the intervention is deliverable by lay health counselors and is grounded in problem solving therapy for primary care and brief behavioral treatment for insomnia. We have named the intervention “DIL” (the Hindi word for “heart” and an acronym for “depression in late life.”) Additional DIL strategies include psychoeducation in self-management of co-occurring medical disorders such as diabetes mellitus, together with assistance in navigation to needed social and economic resources. We present the results of a preliminary open-trial case series involving 21 participants with subsyndromal symptoms of depression, demonstrating feasibility, acceptability, and benefit to participants. We then present the design of a larger confirmatory trial into which 181 participants have been enrolled. “DIL” is a novel and large depression prevent...
Research Interests:
We used two models to simulate a proposed noninferiority trial of radiotherapy (RT) omission in low-risk invasive breast cancer to illustrate how modeling could be used to predict the trial's outcomes, inform trial design, and... more
We used two models to simulate a proposed noninferiority trial of radiotherapy (RT) omission in low-risk invasive breast cancer to illustrate how modeling could be used to predict the trial's outcomes, inform trial design, and contribute to practice debates. The proposed trial was a prospective randomized trial of no-RT vs RT in women age 40 to 74 years undergoing lumpectomy and endocrine therapy for hormone receptor-positive, human epidermal growth factor receptor 2-negative, stage I breast cancer with an Oncotype DX score of 18 or lower. The primary endpoint was recurrence-free interval (RFI), including locoregional recurrence, distant recurrence, and breast cancer death. Noninferiority required the two-sided 90% confidence interval of the RFI hazard ratio (HR) for no-RT vs RT to be entirely below 1.7. Model inputs included published data. The trial was simulated 1000 times, and results were summarized as percent concluding noninferiority and mean (standard deviation) of hazar...
Research Interests:
Research Interests: Psychology, Medicine, Comorbidity, Humans, Major Depressive Disorder, and 14 moreFemale, Male, Regression Analysis, Young Adult, Grief, Aged, Middle Aged, Adult, Age Factors, Psychotropic Drugs, Psychiatric, Severity of Illness Index, Psychology and Cognitive Sciences, and Medical and Health Sciences
To determine the acceptability of clinical interventions for depression prevention, identification of clinical characteristics associated with intervention engagement is needed. The purpose of this study is to describe levels and... more
To determine the acceptability of clinical interventions for depression prevention, identification of clinical characteristics associated with intervention engagement is needed. The purpose of this study is to describe levels and correlates of participant engagement in Problem Solving Therapy (PST) in adults 60 and older with subthreshold depression. As part of a clinical trial to prevent depression among older adults with subthreshold depression, participants who were randomized to receive PST completed 6-8 sessions in which they learned skills to solve self-selected problems that were contributing to stress and reduced quality of life. To measure participants' engagement with PST, interventionists completed 3 scales that rated participants' level of participation in problem solving activities, understanding of the multistep process of PST, and between-session homework effort. Using logistic regression, we examined whether physical health, level of cognitive function, gait ...
Research Interests:
More than 50% of older adults with late-life major depressive disorder fail to respond to initial treatment with first-line pharmacological therapy. To assess typical patterns of response to an open-label trial of extended-release... more
More than 50% of older adults with late-life major depressive disorder fail to respond to initial treatment with first-line pharmacological therapy. To assess typical patterns of response to an open-label trial of extended-release venlafaxine hydrochloride (venlafaxine XR) for late-life depression and to evaluate which clinical factors are associated with the identified longitudinal response patterns. Group-based trajectory modeling was applied to data from a 12-week open-label pharmacological trial conducted in specialty care as part of the Incomplete Response in Late Life: Getting to Remission Study. Clinical prognostic factors, including domain-specific cognitive performance and individual depression symptoms, were examined in relation to response trajectories. Participants included 453 adults aged 60 years or older with current major depressive disorder. The study was conducted between August 2009 and August 2014. Open-label venlafaxine XR (titrated up to 300 mg/d) for 12 weeks....
Research Interests: Psychology, Treatment Outcome, Medicine, Linear models, Humans, and 14 moreMajor Depressive Disorder, Female, Male, Guilt, Rating Scale, Aged, Middle Aged, Prognosis, Disease Progression, Bayes Theorem, Late Life Depression, Venlafaxine, Antidepressive agents, and Sleep initiation and maintenance disorders
Research Interests: Psychology, Clinical Psychology, Psychiatry, Primary Health Care, Medicine, and 15 moreDistress, Anxiety, Problem Solving, Humans, Female, Male, Depressive Disorder, Beck Depression Inventory, African Americans, Aged, Middle Aged, ANXIETY, Psychiatric Status Rating Scales, Affective symptoms, and Medical and Health Sciences
Late-life depression (LLD, major depression occurring in an adult 60 years or older) is a common condition that frequently presents with cognitive impairment. Up to half of individuals with LLD are estimated to have cognitive impairment... more
Late-life depression (LLD, major depression occurring in an adult 60 years or older) is a common condition that frequently presents with cognitive impairment. Up to half of individuals with LLD are estimated to have cognitive impairment greater than that of age- and education-matched comparators, with impairments of episodic memory, speed of information processing, executive functioning, and visuospatial ability being most common. To inform our understanding of the state- versus trait-effects of depression on neuropsychological functioning, and to overcome limitations of previous studies, we utilized baseline data from the longitudinal Pathways study to compare differences in single time point performance on a broad-based neuropsychological battery across three diagnostic groups of older adults, each comprised of unique participants (n = 438): currently depressed (n = 120), previously depressed but currently euthymic (n = 190), and never-depressed (n = 128). Consistent with our hypo...
Research Interests: Clinical Psychology, Cognitive Science, Neuropsychology, Depression, Cognition, and 15 moreAttention, Medicine, Episodic Memory, Executive Function, Humans, Female, Male, Executive Functions, Clinical Sciences, Aged, Longitudinal Studies, Late Life Depression, Cognition disorders, Case Control Studies, and Neuropsychological Tests
BackgroundWhile bipolar disorder (BD) is a leading cause of disability, and an important contributor to disability in BD is cognitive impairment, there is little systematic research on the longitudinal course of cognitive function and... more
BackgroundWhile bipolar disorder (BD) is a leading cause of disability, and an important contributor to disability in BD is cognitive impairment, there is little systematic research on the longitudinal course of cognitive function and instrumental activities of daily living (IADLs) in late-life. In this report, we characterize the 2-year course of cognitive function and IADLs in older adults with BD.MethodWe recruited non-demented individuals 50 years and older with BD I or BD II (n = 47) from out-patient clinics or treatment studies at the University of Pittsburgh. Comparator subjects (‘controls’) were 22 individuals of comparable age and education with no psychiatric or neurologic history, but similar levels of cardiovascular disease. We assessed cognitive function and IADLs at baseline, 1- and 2-year time-points. The neuropsychological evaluation comprised 21 well-established and validated tests assessing multiple cognitive domains. We assessed IADLs using a criterion-referenced,...
Research Interests: Psychology, Neuropsychology, Bipolar Disorder, Cognition, Aging, and 15 moreMedicine, Linear models, Psychological Medicine, Activities of Daily Living, Humans, Female, Male, Aged, Middle Aged, Longitudinal Studies, Disease Progression, Neurosciences, Cognition disorders, Case Control Studies, and Neuropsychological Tests
Research Interests: Psychotherapy, Primary Health Care, Depression, Treatment Outcome, Medicine, and 15 moreProblem Solving, Population, Humans, Major Depressive Disorder, Female, Male, Psychological Intervention, African Americans, Aged, Middle Aged, Public health systems and services research, Randomized Controlled Trial, Psychiatric Services, European Continental Ancestry Group, and Depressive Symptoms
Research Interests: Depression, Mild Cognitive Impairment, Medicine, Linear models, Pathophysiology, and 15 moreHumans, Internal Medicine, Placebo, Female, Male, Donepezil, Aged, Longitudinal Studies, Cognitive Decline, Late Life Depression, Enzyme Linked Immunosorbent Assay, Piperidines, Indans, Medical and Health Sciences, and Antidepressive agents
Research Interests:
Research Interests:
Research Interests:
Purpose To assess patterns of locoregional failure (LRF) in lymph node–positive (LN+) breast cancer patients treated with mastectomy and adjuvant chemotherapy (± tamoxifen) and without postmastectomy radiotherapy (PMRT) in five National... more
Purpose To assess patterns of locoregional failure (LRF) in lymph node–positive (LN+) breast cancer patients treated with mastectomy and adjuvant chemotherapy (± tamoxifen) and without postmastectomy radiotherapy (PMRT) in five National Surgical Adjuvant Breast and Bowel Project trials. Patients and Methods We examined 5,758 patients enrolled onto the B-15, B-16, B-18, B-22, and B-25 trials. Median follow-up time was 11.1 years. Distribution of pathologic tumor size was ≤ 2 cm, 2.1 to 5 cm, and more than 5 cm in 30%, 52%, and 11% of patients, respectively. Distribution of the number of LN+ was one to three, four to nine, and ≥ 10 in 51%, 32%, and 16% of patients, respectively. Ninety percent of patients received doxorubicin-based chemotherapy. Results The overall 10-year cumulative incidences of isolated LRF, LRF with or without distant failure (DF), and DF alone as first event were 12.2%, 19.8%, and 43.3%, respectively. Cumulative incidences for LRF as first event with or without D...
Research Interests: Breast Cancer, Chemotherapy, Radiation Therapy, Survival Analysis, Medicine, and 15 moreHumans, Female, Clinical, Clinical oncology, Mastectomy, Aged, Middle Aged, Doxorubicin, Adult, Methotrexate, Cyclophosphamide, Proportional Hazards Models, Combined Modality Therapy, Breast Neoplasms, and fluorouracil
Purpose National Surgical Adjuvant Breast and Bowel Project (NSABP) Protocol B-18 was designed to determine whether four cycles of doxorubicin and cyclophosphamide (AC) administered preoperatively improved breast cancer disease-free... more
Purpose National Surgical Adjuvant Breast and Bowel Project (NSABP) Protocol B-18 was designed to determine whether four cycles of doxorubicin and cyclophosphamide (AC) administered preoperatively improved breast cancer disease-free survival (DFS) and overall survival (OS) compared with AC administered postoperatively. Protocol B-27 was designed to determine the effect of adding docetaxel (T) to preoperative AC on tumor response rates, DFS, and OS. Patients and Methods Analyses were limited to eligible patients. In B-18, 751 patients were assigned to receive preoperative AC, and 742 patients were assigned to receive postoperative AC. In B-27, 784 patients were assigned to receive preoperative AC followed by surgery, 783 patients were assigned to AC followed by T and surgery, and 777 patients were assigned to AC followed by surgery and then T. Results Results from B-18 show no statistically significant differences in DFS and OS between the two groups. However, there were trends in fa...
Research Interests:
Research Interests:
Randomized trials for selective and indicated prevention of depression in both mixed-aged and older adult samples, conducted in high-income countries (HICs), show that rates of incident depression can be reduced by 20–25% over 1–2 years... more
Randomized trials for selective and indicated prevention of depression in both mixed-aged and older adult samples, conducted in high-income countries (HICs), show that rates of incident depression can be reduced by 20–25% over 1–2 years through the use of psychoeducational and psychological interventions designed to increase protective factors. Recurrence of major depression can also be substantially reduced through both psychological and psychopharmacological strategies. Additional research is needed, however, to address the specific issues of depression prevention in older adults in low- and middle-income countries (LMICs). The growing number of older adults globally, as well as workforce issues and the expense of interventions, makes it important to develop rational, targeted, and cost-effective risk-reduction strategies. In our opinion, one strategy to address these issues entails the use of lay health counselors (LHCs), a form of task shifting already shown to be effective in t...
Research Interests: Early Intervention, Mental Health, Global Health, Developing Countries, Medicine, and 15 morePrevention, Community Health Workers, Humans, Major Depressive Disorder, Cost effectiveness, Common Mental Disorders, Mental health services, Aged, Developed Countries, Major Depression, Low and Middle Income Countries, Older Adult, Cost of Illness, Preventive Health Services, and Antidepressive agents
Research Interests:
Research Interests: Oncology, Breast Cancer, Medicine, Humans, Female, and 14 moreRegression Analysis, Mastectomy, Lancet, Middle Aged, Proportional hazards model, Survival Rate, Proportional Hazards Models, Lumpectomy, Life tables, Combined Modality Therapy, Breast Neoplasms, The Lancet, Neoplasm metastasis, and Medical and Health Sciences
Research Interests:
Research Interests:
In this phase III, multinational, randomized trial, the International Breast Cancer Study Group, Breast International Group, and the National Surgical Adjuvant Breast and Bowel Project will attempt to define the effectiveness of cytotoxic... more
In this phase III, multinational, randomized trial, the International Breast Cancer Study Group, Breast International Group, and the National Surgical Adjuvant Breast and Bowel Project will attempt to define the effectiveness of cytotoxic therapy for patients with locoregional recurrence of breast cancer. We will evaluate whether chemotherapy prolongs disease-free survival and, secondarily, whether its use improves overall survival and systemic disease-free survival. Quality of life measurements will be monitored during the first 12 months of the study. Women who have had a previous diagnosis of invasive breast cancer treated by mastectomy or breast-conserving surgery and who have undergone complete surgical excision of all macroscopic disease but who subsequently develop isolated local and/or regional ipsilateral invasive recurrence are eligible. Patients are randomized to observation/no adjuvant chemotherapy or to adjuvant chemotherapy; all suitable patients receive radiation, hor...
Research has shown that in mixed effect longitudinal models, influential observations can have a large effect on the estimates of subject-specific parameters. Furthermore, they cannot always be detected by the classical Cook’s distance... more
Research has shown that in mixed effect longitudinal models, influential observations can have a large effect on the estimates of subject-specific parameters. Furthermore, they cannot always be detected by the classical Cook’s distance due to potentially large between subject variation. Thus, influential observations should be approached by conditioning on the subjects. However, no rigorous approach has been developed for influential observation detection for multivariate longitudinal mixed models where more than one response is measured for each subject at each time point. We propose a multivariate conditional Cook’s distance for this more general situation. Examples are given to illustrate how the influential observation in one characteristic changes the effects of both characteristics.
Research Interests:
We investigated the association between longitudinally measured depression scores and survival times simultaneously for paired spouse data from the Cardiovascular Health Study (CHS). We propose a joint model incorporating within pair... more
We investigated the association between longitudinally measured depression scores and survival times simultaneously for paired spouse data from the Cardiovascular Health Study (CHS). We propose a joint model incorporating within pair correlations, both in the longitudinal and survival processes. We use bivariate linear mixed-effects models for the longitudinal processes, where the random effects are used to model the temporal correlation within each subject and the correlation across outcomes between subjects. For the survival processes, we incorporate gamma frailties into Weibull proportional hazards models to account for the correlation between survival times within pairs. The two sub-models are then linked through shared random effects, where the longitudinal and survival processes are conditionally independent given the random effects. Parameter estimates are obtained via the EM algorithm by maximizing the joint likelihood for the bivariate longitudinal and bivariate survival da...
Research Interests:
508 Background: Preclinical studies report that T can boost RT effectiveness. The primary aim of this trial assessed the efficacy of concurrent T + RT vs RT alone in preventing recurrence of ipsilateral breast cancer, ipsilateral skin... more
508 Background: Preclinical studies report that T can boost RT effectiveness. The primary aim of this trial assessed the efficacy of concurrent T + RT vs RT alone in preventing recurrence of ipsilateral breast cancer, ipsilateral skin cancer, or ipsilateral DCIS (IBTR) in women with DCIS. Methods: Eligibility: Women ≥18 yrs, ECOG performance status 0 or 1, DCIS resected by lumpectomy, and clear margins. Whole-breast RT after randomization was with 25+ fractions or accelerated with 16-17 fractions. RT boost was allowed. Centralized HER2 testing and ER and/or PR were required before entry. Stratification was by menopausal status, adjuvant endocrine therapy plan, and nuclear grade. T was given at 8 mg/kg IV within 1 wk before and 5 days after RT began (Dose 1) and at 6 mg/kg IV 3 wks after Dose 1 (Dose 2). Definitive intent-to-treat primary analysis was to be conducted when either 163 IBTR events were recorded or when all accrued pts were on study for ≥5 yrs. Results: 2014 pts were ran...
Research Interests:
1000 Background: NSABP B-32, the largest surgical prospective randomized phase III trial was designed to compare overall survival (OS), disease-free survival (DFS), and morbidity between SNR alone vs SNR + AD in SN negative (-) pts. We... more
1000 Background: NSABP B-32, the largest surgical prospective randomized phase III trial was designed to compare overall survival (OS), disease-free survival (DFS), and morbidity between SNR alone vs SNR + AD in SN negative (-) pts. We present 10 yr outcome data for primary endpoints as well as updated data on the effect of occult metastases, found later in the SN by central, detailed pathologic analysis. Methods: 5,611 women with operable, clinically N0, invasive breast cancer were randomized to SNR + AD (Group [Grp] 1) or to SNR alone with AD only if SNs were positive (Grp2). 3,989 (71.1%) of 5,611 pts were SN-. 3,986 (99.9%) of these SN- pts had follow-up information: Grp 1: 1,975, Grp 2:2,011. Median time on study was 9.4 yrs. Cox proportional hazard models adjusting for study stratification variables were used to compare OS and DFS between the two groups. Two-sided p values were used. HR values > 1 indicate a more favorable outcome in Grp 1 Results: At 10 yrs, there continue...
Research Interests:
TPS657 Background: Asignificant amount of DCIS is ER negative and/or overexpresses HER2. This provides an opportunity to test molecular therapy in DCIS. In xenograft models and cell lines, T boosts RT effectiveness. In T-treated HER2+... more
TPS657 Background: Asignificant amount of DCIS is ER negative and/or overexpresses HER2. This provides an opportunity to test molecular therapy in DCIS. In xenograft models and cell lines, T boosts RT effectiveness. In T-treated HER2+ patients, apoptosis occurs within 1 wk of single agent T use, with T found in ductal aspirates. Ample safety evidence for T exists. T given during whole breast irradiation (WBI) may improve results for Lx-resected HER2+ DCIS. A trial to examine this question will enhance the understanding of breast tumor biology and the prevention of such tumors and could possibly extend breast-conserving surgery benefits for women with DCIS. Methods: After Lx for pure DCIS, each patient’s DCIS lesion is centrally tested for HER2 by IHC analysis. HER2 2+ tumors undergo FISH analysis. HER2 3+ or FISH+ patients can be randomly assigned to 2 doses of T, 3 weeks apart during WBI or to WBI alone. Women ≥18 yrs. with a margin-clear Lx for pure DCIS, with ECOG status 0/1 who ...
Research Interests:
Preface Review of Topics in Probability and Statistics Introduction to Probability Conditional Probability Random Variables The Uniform distribution The Normal distribution The Binomial Distribution The Poisson Distribution The... more
Preface Review of Topics in Probability and Statistics Introduction to Probability Conditional Probability Random Variables The Uniform distribution The Normal distribution The Binomial Distribution The Poisson Distribution The Chi-Squared Distribution Student's t-distribution The F-distribution The Hypergeometric Distribution The Exponential Distribution Exercises Use of Simulation Techniques Introduction What can we accomplish with simulations? How to employ a simple simulation strategy Generation of Pseudorandom Numbers Generating Discrete and Continuous random variables Testing Random Number Generators A Brief Note on the Efficiency of Simulation Algorithms Exercises The Central Limit Theorem Introduction The Strong Law of Large Numbers The Central Limit Theorem Summary of the Inferential Properties of the Sample Mean Appendix: Program Listings Exercises Correlation and Regression Introduction Pearson's Correlation Coefficient Simple Linear Regression Multiple Regression Visualization of Data Model Assessment and Related Topics Polynomial Regression Smoothing Techniques Appendix: A Short Tutorial in Matrix Algebra Exercises Analysis of Variance Introduction One-Way Analysis of Variance General Contrast Multiple Comparisons Procedures Gabriel's method Dunnett's Procedure Two-Way Analysis of Variance: Factorial Design Two-Way Analysis of Variance: Randomized Complete Blocks Analysis of Covariance Exercises DiscreteMeasures of Risk Introduction Odds Ratio (OR) and Relative Risk (RR) Calculating risk in the presence of confounding Logistic Regression Using SAS and R for Logistic Regression Comparison of Proportions for Paired Data Exercises Multivariate Analysis The Multivariate Normal Distribution One and Two Sample Multivariate Inference Multivariate Analysis of Variance Multivariate Regression Analysis Classification Methods Exercises Analysis of Repeated Measures Data Introduction Plotting Repeated Measures Data Univariate Approaches for the Analysis of Repeated Measures Data Covariance Pattern Models Multivariate Approaches Modern Approaches for the Analysis of Repeated Measures Data Analysis of Incomplete Repeated Measures Data Exercises NonparametricMethods Introduction Comparing Paired Distributions Comparing Two Independent Distributions Kruskal-Wallis Test Spearman's rho The Bootstrap Exercises Analysis of Time to Event Data Incidence Density (ID) Introduction to Survival Analysis Estimation of the Survival Curve Estimating the Hazard Function Comparing Survival in Two Groups Cox Proportional Hazards Model Cumulative Incidence Exercises Sample size and power calculations Sample sizes and power for tests of normally distributed data Sample size and power for Repeated Measures Data Sample size and power for survival analysis Constructing Power Curves Exercises Appendix A: Using SAS Introduction Data input in SAS Some Graphical Procdures: PROC PLOT and PROC CHART Some Simple Data Analysis Procedures Diagnosing errors in SAS programs Exercises Appendix B: Using R Introduction Getting started Input/Output Some Simple Data Analysis Procedures Using R for plots Comparing an R-session to a SAS session Diagnosing problems in R programs Exercises References Index
513 Background: ILRR is associated with a high risk of developing breast cancer distant metastases and death. The CALOR trial (NCT00074152) investigated the effectiveness of CT following local therapy for ILRR. Previously reported results... more
513 Background: ILRR is associated with a high risk of developing breast cancer distant metastases and death. The CALOR trial (NCT00074152) investigated the effectiveness of CT following local therapy for ILRR. Previously reported results at 5-yrs median follow-up (MFU) showed significant benefit of CT for ER- ILRR, but further follow-up was required in ER+ ILRR. This report presents results at 8.8 yrs MFU within ER status cohorts. Methods: CALOR is an open-label, randomized trial for patients with completely excised ILRR after unilateral breast cancer. Eligible patients were randomized to CT (selected by the investigator; multidrug for at least 3 months recommended) or No-CT, and stratified by prior CT, hormone-receptor (ER, PR) status, and location of ILRR. Patients with ER and/or PR positive ILRR received adjuvant endocrine therapy. Radiation therapy was mandated for patients with microscopically involved margins, and anti-HER2 therapy was optional. Endpoints are disease-free sur...
Research Interests:
Research Interests: Statistics and Biometrics
Down syndrome (DS) predisposes individuals to early Alzheimer's disease (AD). Using Pittsburgh Compound B ([C]PiB), a pattern of striatal amyloid beta (Aβ) that is elevated relative to neocortical binding has been reported,... more
Down syndrome (DS) predisposes individuals to early Alzheimer's disease (AD). Using Pittsburgh Compound B ([C]PiB), a pattern of striatal amyloid beta (Aβ) that is elevated relative to neocortical binding has been reported, similar to that of nondemented autosomal dominant AD mutation carriers. However, it is not known whether changes in striatal and neocortical [C]PiB retention differ over time in a nondemented DS population when compared to changes in a nondemented elderly (NDE) population. The purpose of this work was to assess longitudinal changes in trajectories of Aβ in a nondemented DS compared to an NDE cohort. The regional trajectories for anterior ventral striatum (AVS), frontal cortex, and precuneus [C]PiB retention were explored over time using linear mixed effects models with fixed effects of time, cohort, and time-by-cohort interactions and subject as random effects. Significant differences between DS and NDE cohort trajectories for all 3 region of interests were observed (p < 0.05), with the DS cohort showing a faster accumulation in the AVS and slower accumulation in the frontal cortex and precuneus compared to the NDE cohort. These data add to the previously reported distinct pattern of early striatal deposition not commonly seen in sporadic AD by demonstrating that individuals with DS may also accumulate Aβ at a rate faster in the AVS when compared to NDE subjects.
Research Interests:
Radiotherapy after breast conservation has become the standard of care. Prior meta-analyses on effects of radiotherapy predated availability of gene expression profiling (GEP) to assess recurrence risk and/or did not include all relevant... more
Radiotherapy after breast conservation has become the standard of care. Prior meta-analyses on effects of radiotherapy predated availability of gene expression profiling (GEP) to assess recurrence risk and/or did not include all relevant outcomes. This analysis used GEP information with pooled individual-level data to evaluate the impact of omitting radiotherapy on recurrence and mortality. We considered trials that evaluated or administered radiotherapy after lumpectomy in women with low-risk breast cancer. Women included had undergone lumpectomy and were treated with hormonal therapy for stage I, ER+ and/or PR+, HER2- breast cancer with Oncotype scores no greater than 18. Recurrence-free interval (RFI), type of RFI (locoregional or distant), and breast cancer-specific and overall survival were compared between no radiotherapy and radiotherapy using adjusted Cox models. All statistical tests were two-sided. The final sample included 1778 women from seven trials. Omission of radioth...
Research Interests:
Several studies have reported a high risk of local disease recurrence (LR) and locoregional disease recurrence (LRR) in patients with breast cancer after neoadjuvant chemotherapy (NCT) and breast-conserving therapy (BCT). The objective of... more
Several studies have reported a high risk of local disease recurrence (LR) and locoregional disease recurrence (LRR) in patients with breast cancer after neoadjuvant chemotherapy (NCT) and breast-conserving therapy (BCT). The objective of the current study was to identify potential risk factors for LR and LRR after NCT and BCT. Individual patient data sets from 9 studies were pooled. The outcomes of interest were the occurrence of LR and/or LRR. A 1-stage meta-analytic approach was used. Cox proportional hazards regression models were applied to identify factors that were predictive of LR and LRR, respectively. A total of 9 studies (4125 patients) provided their data sets. The 10-year LR rate was 6.5%, whereas the 10-year LRR rate was 10.3%. Four factors were found to be associated with a higher risk of LR: 1) estrogen receptor-negative disease; 2) cN + disease; 3) a lack of pathologic complete response in axilla (pN0); and 4) pN2 to pN3 disease. The predictive score for LR determin...
Research Interests:
Purpose Isolated locoregional recurrence (ILRR) predicts a high risk of developing breast cancer distant metastases and death. The Chemotherapy as Adjuvant for LOcally Recurrent breast cancer (CALOR) trial investigated the effectiveness... more
Purpose Isolated locoregional recurrence (ILRR) predicts a high risk of developing breast cancer distant metastases and death. The Chemotherapy as Adjuvant for LOcally Recurrent breast cancer (CALOR) trial investigated the effectiveness of chemotherapy (CT) after local therapy for ILRR. A report at 5 years of median follow-up showed significant benefit of CT for estrogen receptor (ER)-negative ILRR, but additional follow-up was required in ER-positive ILRR. Patients and Methods CALOR was an open-label, randomized trial for patients with completely excised ILRR after unilateral breast cancer. Eligible patients were randomly assigned to receive CT or no CT and stratified by prior CT, hormone receptor status, and location of ILRR. Patients with hormone receptor-positive ILRR received adjuvant endocrine therapy. Radiation therapy was mandated for patients with microscopically involved margins, and anti-human epidermal growth factor receptor 2 therapy was optional. End points were diseas...