Mandi Schwartz ’11, the women’s hockey player who battled cancer for more than two years, died Sunday morning, the News has learned. She was 23.

Diagnosed with acute myeloid leukemia in December 2008, Schwartz fought courageously against cancer while her struggle gripped campus, the hockey world, the national media, and thousands of strangers across the continent.

Schwartz enrolled at Yale with the class of 2010, but left campus for the first time during the winter of her junior year. Typically the cheeriest, hardest-working player on the ice, Schwartz had felt ill for weeks leading up to her Dec. 8, 2008 diagnosis, but had attributed her fatigue to the everyday wear-and-tear of classes and varsity athletics.

“I was sick all semester, and I didn’t know why,” Schwartz, a native of Saskatchewan, Canada, told the News in January 2010. “I thought I was anemic or something … I just felt really weird, and I didn’t know what it was — just infection and illnesses all the time. Toward the end, my body got really sore, and I thought it was just from working out.”

Though an initial diagnosis showed that Schwartz tested positive for anemia, the life-changing news came three days later: she had leukemia.

Schwartz left campus for Canada on Dec. 9, 2008, and began a 130-day stretch of hospitalization. It would be her first of many such hospital stays and chemotherapy treatments.

Throughout her battle with cancer, Schwartz had one brief return to her former life as a Yale student in January 2010. She geared up for practice and attended classes for just four months before learning in April — a few days before the second University-wide bone marrow drive was held in her honor — that her cancer had returned.

Schwartz’s cause entered the national spotlight shortly after the hockey player departed campus for the second time.

That summer, Schwartz’s friends, family, and teammates spent months raising awareness and funds for her cause. Doctors had determined that Schwartz needed a bone marrow or stem cell transplant to survive, and her supporters worked to organize drives in hopes of finding an appropriate match. Schwartz’s story appeared on ESPN, ABC News, CBS News, and in other major media outlets.

The media blitz and donor search seemed to pay off when Schwartz’s caregivers announced in early August that two stem cell matches had been found, and she received a transplant at the Seattle Cancer Care Alliance on Sept. 22, 2010. Though she spent weeks recuperating, battling a weak immune system and a high susceptibility to disease in the process, the procedure appeared successful.

But Schwartz learned in December 2010 that she had relapsed once more, approximately 85 days after her transplant. She briefly resumed treatment, but Schwartz’s family announced in early January that she would not continue curative chemotherapy.

Since then, Schwartz had undergone outpatient palliative chemotherapy — treatment aimed at reducing symptoms, not reversing or curing the disease — in her hometown of Wilcox in Regina, Saskatchewan.

A Facebook message was sent by the group “Become Mandi’s Hero” Sunday afternoon, explaining that Schwartz has passed away at 10:35 a.m. Pacific Standard Time. According to the message, she was with family, friends, and her fiancé, Kaylem Prefontaine, at the time.

She is survived by her parents, Rick and Carol Schwartz, and two brothers, Rylan and Jaden.

Correction: April 3, 2011

An earlier version of this article misstated the year in which Schwartz returned to campus. It was 2010 not 2009.