A hero in the breast cancer community passed away on Tuesday at the age of 57.

Dr. Jerri Nielsen made headlines in 1999 after she diagnosed herself with breast cancer while working as the only doctor at the Amundsen-Scott South Pole Research Station. While marooned there during the brutal Antarctic winter, Nielsen found a lump in her breast and performed a biopsy on herself. She then began self-administering chemotherapy treatments the U.S. Air Force had parachuted to her at the station. When the climate warmed up several months later, Nielsen was able to fly to her home state for further treatment. Her cancer went into remission, but returned in 2005 and spread to her bones, liver and, later, her brain.

Nielsen’s self-diagnosis and treatment, achievements and struggles are chronicled in her bestselling book, Ice Bound. 

Watch this video about Nielsen’s remarkable story via the Associated Press: