Professor Mary O'Brien

Consultant Medical Oncologist MD FRCP

Specialism: Breast, Lung

Available at: Cavendish, Sutton

Special interests:

  • chemotherapy for lung cancer
  • biological therapy for lung cancer
  • chemotherapy for breast cancer
  • endocrine therapy for breast cancer


Dr O'Brien has both a private and an NHS practice at The Royal Marsden. She was born in Northern Ireland and studied medicine at Trinity College Dublin. She works as a medical oncologist at The Royal Marsden in Sutton, Surrey, and until October 2003, also worked at the Kent Oncology Centre in Maidstone.

Dr O’Brien treats breast and lung cancer including mesothelioma. She is currently Head of the Lung Unit, past chair of the SWL lung cancer tumour working group, chair of the EORTC lung cancer group and principal investigator of a number of European trials.

For lung and breast cancer she is interested in all aspects of treatment development through clinical trials. She is also interested in the supportive treatment of cancer patients including the use of acupuncture for breathlessness.

Clinical units