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Mariana Chavez MacGregor, MD

MD Anderson Cancer Center
Houston, Texas

Titles and Affiliations

Associate Professor, Department of Breast Medical Oncology and Department of Health Services Research

Research area

Investigating factors that influence the rate of breast cancer treatment completion in underrepresented or understudied populations.


There are several factors that influence whether a breast cancer patient completes their treatment plan. In order to enhance the quality of cancer care, identify areas of greater need, and ultimately improve outcomes and reduce disparities, a better understanding of the patterns of treatment completion is fundamental. Dr. Chavez MacGregor is evaluating the rates of treatment completion, the incidence of treatment-related toxicities, and access to care in underrepresented or understudied populations, including racial/ethnic minorities and older patients. Her team hopes to gain new insights that will help identify areas of need and inform the design of specific interventions. The results of these studies will potentially improve care, influence policy, and address some of the challenges that breast cancer patients in underrepresented populations experience.

Progress Thus Far

With funding from BCRF, Dr. Chavez MacGregor conducted an important study evaluating the impact of Medicaid access on adjuvant chemotherapy initiation. She observed that among patients with early-stage breast cancer treated with adjuvant chemotherapy, those with access to Medicaid had fewer delays in the start of treatment. In addition, this Medicaid access had an impact on reducing racial disparities by decreasing the gap in the proportion of Black and Hispanic patients experiencing delays in chemotherapy initiation. Access to Medicaid also reduced the time to surgery in this vulnerable population. Together, these important findings highlight the relevance of increasing access to healthcare by implementing policies aimed at eliminating barriers and increasing access to care for all.

What’s Next

Building on prior investigations, her team is evaluating how parameters such as the number of emergency room visits or hospitalizations, societal-level factors including socioeconomic deprivation, insurance coverage, and financial toxicity, are associated with the rates of treatment non-completion. Dr. Chavez MacGregor and her colleagues are also evaluating whether treatment non-completion is more frequent among underrepresented and understudied patient populations and how this contributes to adverse outcomes. Her team is leveraging existing large cancer registries and databases to obtain real world evidence to address these questions. Understanding how these factors influence cancer care delivery for patients with breast cancer is essential for addressing disparities and enables the identification of areas where improvements are needed to enhance the quality of cancer care. In turn, these results can lead to tailored strategies that result in better outcomes, reduced disparities, and an improved quality of life for patients.


Mariana Chavez MacGregor, MD is a tenured associate professor in the Health Services Research Department and the Breast Medical Oncology Department of MD Anderson Cancer Center. She received a master’s degree in Clinical Epidemiology at the Netherlands Institute for Health and Sciences with comprehensive training in study design for conducting large cohort studies and data analysis. And completed a Medical Oncology fellowship at the University of Texas MD Anderson Cancer Center prior to joining the faculty there.

Dr. Chavez MacGregor pursues an academic career in breast cancer research and as a medical oncologist devotes her clinical practice to caring for breast cancer patients. Her research focuses on evaluating patterns of care, adherence, toxicities, and complications of cancer treatment, particularly among vulnerable populations. She has significant experience in the design of high-quality observational studies to answer clinically relevant questions including those pertaining to cancer care delivery and utilization. In addition, Dr. Chavez MacGregor has been deeply involved in guideline methodology and the development of national and international treatment guidelines.

BCRF Investigator Since


Donor Recognition

The Estée Lauder Companies' Employee Fundraising Award

Areas of Focus

Survivorship Treatment