She was diagnosed with metastatic breast cancer at age 37, and began to document her experiences with the terminal illness using illustrations and essays. Her works were compiled into a graphic novel called In-Between Days. The book was a finalist for the 2016 Governor General's Award for English-language non-fiction, and put Harrison on the list of 16 Torontonians to Watch. She has written for The Walrus and has been featured in the Globe and Mail, Creative Mornings, HuffPost Canada, Kirkus Reviews, The New York Times, and WNYC. She has also spoken on CBC Radio about her experience. She died on April 27, 2019 at her Toronto home at age 42.