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Mariana Chavez MacGregor, MD, MSc

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

Current Research

  • Seeking to improve breast cancer outcomes by preventing delays in treatment. 
  • A pilot study is conducted to determine if patient navigators can effectively reduce the time to treatment in an underserved population.
  • This study will help to improve outcomes in breast cancer patients by ensuring access to high-quality care.
Early stage breast cancer is treatable with chemotherapy, but recurrence after treatment remains a concern. When treatment is delayed, the risk of recurrence can result in poor outcomes. Dr. Chavez MacGregor is conducting an intervention study to reduce the time to treatment in a vulnerable population of breast cancer patients. 

Full Research Summary

Improvements in breast cancer treatment and early detection have resulted in an important decrease in mortality rates. Among patients with early stage breast cancer, the use of adjuvant chemotherapy significantly decreases the risk of recurrence and improves overall survival. However, patients who experience delays in the initiation of chemotherapy may not have the same improved survival, because of the treatment delays. 

In previous work, Dr. Chavez MacGregor found that patients who experienced delays in the intiation of treatment were more likely to die from their disease compared to those who received chemotherapy within 30 days after surgery. Her studies showed that delays are more likely to occur in patients with more comorbidities, those of Hispanic or African American race/ethnicity, patients without a partner, Medicare or Medicaid beneficiaries, and those belonging to a low socioeconomic status. Since patients that experience delays in the administration of chemotherapy are at an increased risk of death, every effort should be made to understand and remove barriers associated with treatment delays.

In her Conquer Cancer Foundation award supported by BCRF, Dr. Chavez MacGregor is testing a targeted intervention in a vulnerable population of breast cancer patients to reduce the time to breast cancer treatment and faciliate access to care.  She will randomize patients to a targeted intervention using patient navigators vs. routine clinical care. This is the first study to evaluate the effect of patient navigators and health promoters in reducing the time to chemotherapy  in breast cancer patients.

As part of the study Dr. Chavez MacGregor’s team will identify modifiable determinants where interventions would have great impact, increasing the potential to improve outcomes and reduce health disparities.


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