Marisa C. Weiss, M.D.

Chief Medical Officer & Founder

Marisa C. Weiss, M.D. is the founder and chief medical officer of Breastcancer.org, the world’s leading online resource for expert medical and personal information on breast health and breast cancer — reaching 130 million people globally over the past 19 years.

A breast oncologist with more than 30 years of active practice in the Philadelphia region, Dr. Weiss is regarded as a visionary advocate for her innovative and steadfast approach to informing and empowering individuals to protect their breast health and overcome the challenges of breast cancer.

Dr. Weiss is the author of four critically acclaimed books on breast cancer and breast health: Living Beyond Breast Cancer and Living Well Beyond Breast Cancer, coauthored with her mother, Ellen Weiss (1998, 2010); Taking Care of Your “Girls:” A Breast Health Guide for Girls, Teens, and In-Betweens, coauthored with her daughter, Isabel Friedman (2008); and 7 Minutes!: How to Get the Most from Your Doctor Visit (2007).

A renowned leader in the field of breast cancer, Dr. Weiss is frequently called on by the media as a subject matter expert and respected voice of breast cancer patients. She has been a repeat guest on NBC’s TODAY Show, NPR, CNN’s medical features, The Dr. Oz Show and more. Dr. Weiss is a member of the Center for Disease Control’s Federal Advisory Committee on Breast Cancer in Young Women.

Dr. Weiss currently practices at Lankenau Medical Center, part of Main Line Health, a five-hospital health system in the suburbs of Philadelphia, where she serves as director of breast radiation oncology and director of breast health outreach. She also served on the National Cancer Institute Director’s Consumer Liaison Group for seven years.

In 2019, Dr. Weiss was honored by the Main Line Chamber of Commerce with the Helena Devereux Women in Leadership Award for her outstanding work in the areas of business excellence, community service, exceptional leadership, and the advancement of all people.