With ghostwriter Maryanne Vollers, Nielsen's story was told in the autobiographical book Ice Bound: A Doctor's Incredible Story of Survival at the South Pole, which relates the story of her discovery by self-examination that she had developed breast cancer while serving at the Amundsen-Scott South Pole Station during the Antarctic winter of 1999.

Nielsen's saga began in 1999, when she took a year's sabbatical at the Amundsen-Scott South Pole Station on Antarctica. This perilous region experiences almost total darkness for six months of the year, and winter temperatures can plummet to 100 degrees below zero.

In the course of her work at the research station, Nielsen discovered a lump in her breast. After consulting U.S. physicians via email, she performed a biopsy upon herself, and later began self-administered chemotherapy treatments using supplies from a risky July cargo drop to ensure her survival until conditions permitted her rescue several months later. She was picked up in an equally dangerous mid-October landing.

Nielsen's account of her dilemma also details a personal journey that led her to fall in love with the forbidding region of Antarctica. Ice Bound became a New York Times bestseller; and in 2001, Dr. Nielsen was interviewed by popular TV talk-show host Rosie O'Donnell. In 2003 CBS released Ice Bound as a made-for-TV movie starring Susan Sarandon.

In 2003, Nielsen was selected as Irish-American of the Year.[citation needed] She is divorced.[citation needed] Nielsen is from Ohio.