Meet the Lifestyle Medicine  Program's multidisciplinary team of clinicians.


Betsy O'Donnell

Elizabeth K. O’Donnell, MD
Meet Dr. O'Donnell (Video)

Dr. O’Donnell is the Director of Lifestyle Medicine and a medical oncologist in the Multiple Myeloma Disease Center at the Massachusetts General Hospital. Dr. O’Donnell’s interest in exercise intervention and lifestyle medicine is born out of her own passion for athletics and personal health. As an undergraduate at Yale University, Dr. O’Donnell was a Division I All-American in the sport of lacrosse. At MGH, she works to empower cancer patients to reach their optimal level of wellness before, during, and after cancer treatment. Her focus is on lifestyle interventions including regular physical activity and healthy diet to improve cancer outcomes.

Behavioral Medicine

Rachel Millstein

Rachel A. Millstein, PhD, MHS
Meet Dr. Millstein (Video)

Dr. Millstein is an Assistant Professor and clinical health psychologist with the MGH Behavioral Medicine Program. Her clinical work includes the use of mind-body approaches and evidence-based strategies for managing stress/anxiety, depression, weight, and health conditions. Her research focuses on developing physical activity and diet interventions for disease populations including cancer and prevention. She enjoys running, triathlons, dog walks, and hot yoga.

Medical Oncology

Betsy O'Donnell

Elizabeth K. O’Donnell, MD
Meet Dr. O'Donnell (Video)




Amy Comander, MD

Amy Comander, MD

Dr. Amy Comander is a breast oncologist at the Massachusetts General Hospital Cancer Center. She is Director of Breast Oncology and Cancer Survivorship at the Mass General Cancer Center in Waltham and at Newton Wellesley Hospital. She has a strong interest in cancer survivorship and lifestyle medicine, and she is dedicated to improving the quality of life and outcome of cancer patients through important lifestyle interventions, including exercise, diet, and mind/body interventions. She has completed board certification through the American College of Lifestyle Medicine. She promotes healthy lifestyles for both her active treatment patients as well as those in the survivorship phase of care. She practices what she preaches, having run 13 marathons, including 8 consecutive Boston Marathons for charitable causes, with the goal to develop cancer survivorship and wellness programs at the Massachusetts General Hospital Cancer Center. In collaboration with Dr Beth Frates, she has launched PAVING the Path to Wellness, a 12 week lifestyle medicine based survivorship program for women with breast cancer. She has co-authored the PAVING the Path to Wellness workbook, which is used by participants in the PAVING program.


Loren Winters

Loren N. Winters, ANP-BC, OCN, RYT, AHC
Meet Loren (Video)

Loren Winters is an oncology nurse practitioner in the MGH Center for Breast Cancer. She specializes in cancer survivorship particularly in healthy lifestyle behaviors and the use of integrative therapies for self-care. Loren is also an outdoor sports enthusiast, yoga teacher and an Ayurvedic Health Counselor.


Carol Sullivan

Carol E. Sullivan, MS, RD, CSO, LDN
Meet Carol (Video)

Carol is a Registered Dietitian with more than 15 years of experience in the field, including more than a decade practicing as a Certified Specialist in Oncology Nutrition at MGH as a Senior Clinical Dietitian. Her pragmatic and individualized approach to nutrition has helped many thrive through the challenges of cancer diagnosis and treatment and the often-confusing time after treatments. She is passionate about helping people feel better through eating healthy food and movement. Carol competed as a collegiate division I athlete and now enjoys yoga and the comradery of group running, having completed 13 marathons including 8 Boston Marathons, countless races and dabbling in the ultra-distance.


Samantha Bateman

Samantha Bateman, MS, RDN, CSO, LDN

Samantha Bateman is a board certified specialist in oncology nutrition. She has been with Mass General since March 2020. She enjoys providing evidence-based medical nutrition therapy and support to individuals with cancer and cancer survivors. Samantha follows patients in the main campus Cancer Center, pediatric patients in the Proton Center, and patients in the Boston Lifestyle Medicine Clinic.

Physical Medicine & Rehabilitation

Sasha Knowlton

Sasha E. Knowlton, MD
Meet Dr. Knowlton (Video)

Dr. Knowlton is the Assistant Director of Cancer Rehabilitation in the Department of Physical Medicine and Rehabilitation and sees patients at Massachusetts General Hospital and Spaulding Rehabilitation Hospital. She is a physiatrist specializing in cancer rehabilitation and treats patients at all stages of diagnosis, treatment and survivorship to address functional impairments, pain and quality of life. Dr. Knowlton is an avid skier and is passionate about improving fitness and functional independence in her patients.