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Mariana Chavez MacGregor, MD

Associate Professor
The University of Texas MD Anderson Cancer Center
Houston, Texas
Conquer Cancer, the ASCO Foundation

Current Research

Goal: To improve breast cancer outcomes by preventing delays in treatment.

Impact: Dr. MacGregor has identified populations that are less likely to receive prompt treatment, which will help her and her team design interventions specific to these patients’ needs and challenges.

What’s next: Her team will continue analyzing patient data derived from her studies. The results will inform our understanding of specific barriers to care in underserved populations and help to identify which of these challenges could be modified to reduce time to treatment.

Treatment with chemotherapy can reduce the risk of recurrence and improve overall survival in patients with early-stage breast cancer. Delays in treatment are associated with poor outcomes. Having identified several groups of patients that are more likely to experience delays in the initiation of chemotherapy, Dr. MacGregor is working to develop personalized ways to overcome barriers to care in these populations and improve outcomes. 

Full Research Summary

Research area: Pursuing ways to reduce the time to breast cancer treatment and to facilitate access to care for vulnerable patients. 

Impact: The use of chemotherapy improves the outcomes of patients with early-stage breast cancer. Despite this benefit, several studies have shown that a delay in chemotherapy is associated with worse clinical outcomes for these patients. The reasons for delays are complex and not clearly understood. Dr. MacGregor is determining why those delays occur with the goal of designing interventions to overcome these barriers and improve timely treatment and outcomes for patients. 

Current investigation: Identifying and assessing the barriers to and facilitators of initiating chemotherapy by conducting extensive qualitative interviews of breast cancer patients who experienced treatment delays.

What she’s learned so far: In her Conquer Cancer, the ASCO Foundation project supported by BCRF, Dr. McGregor has developed and tested a comprehensive bilingual interview guide. She and her team have identified that Hispanic and African American patients, Medicare, and Medicaid beneficiaries, and those with more comorbidities or of low socioeconomic status are at higher risk of experiencing delays. The team has recruited a large cohort of patients and found when discussing their initiation of chemotherapy, patients describe barriers and facilitators at different levels – personal, family and community related, financial, and communication with the medical team. Explicit insight into chemotherapy delay was rare but engaging women in the treatment process at multiple levels appears to facilitate chemotherapy initiation. 

What’s next: Dr. MacGregor and her team, in partnership with one of the top data analytic teams in the country, will continue to analyze the data from her studies. The results will be presented - in a talk entitled, “Treatment differences and consequences” - at the 2020 San Antonio Breast Cancer Symposium, “The Disparity Crisis in Breast Cancer” Educational Session. 


Dr. Mariana Chavez MacGregor is a medical oncologist with a clinical practice dedicated to the care of patients with breast cancer. After finishing medical school at the Universidad Nacional Autónoma de México, she obtained a Master in Sciences degree in Clinical Epidemiology at the Netherlands Institute of Health and Sciences. She completed her Clinical Residency in Internal Medicine at Barnes-Jewish Hospital/Washington University School of Medicine followed by a Clinical Fellowship in Medical Oncology at The University of Texas MD Anderson Cancer Center. She is an Associate Professor at The University of MD Anderson Cancer Center, holding a primary appointment in the Health Services Research Department, and a joint appointment in the Breast Medical Oncology Department.

In addition to a busy clinical practice, Dr. Chavez MacGregor is committed to an academic career, conducting research focused on breast cancer outcomes and disparities. She has extensive experience evaluating patterns of care, toxicities and complications of cancer treatment. In addition, she has been involved in the planning, design and implementation of clinical trials and is an active member of the global research community SWOG. She has received a number of awards including the SWOG Young investigator award and the Multinational Association of supportive Care in Cancer (MASCC) Young Investigator Award. She received the Achievement in Clinical Research Award and was recently honored with the MD Anderson Faculty Scholar Award. She holds leadership positions within ASCO, currently serving as the chair-elect of the Clinical Practice Guidelines Committee. Dr. Chavez MacGregor has written more than 100 articles, review articles, invited commentaries, and book chapters on breast cancer

Large Researcher Headshot - Mac Gergor Mariana

BCRF Investigator Since


Donor Recognition

The Estée Lauder Companies' Employee Fundraising Award

Area(s) of Focus