GRAND RAPIDS, Mich. (WOOD) — A Spectrum Health orthopedic surgeon is suing the health care giant, saying she was fired while she was on leave battling breast cancer.

Dr. Susan Day, 53, is claiming she was fired because of her concerns about billing and because a colleague wanted to steal her patients. In her lawsuit, she also says she was the victim of sexual discrimination and ageism, and her firing violated the Americans with Disabilities Act.

Spectrum Health denies the allegations.

Day started working at Blodgett Hospital in 1997 after graduating from Michigan State University. She’s also taught at MSU and Grand Valley State University.

Day had offices at 4100 Lake Drive SE and performed surgeries on the Blodgett campus.

Spectrum Health employees 24 Hour News 8 talked to would not go on the record, but said Day was known for being an exceptionally prolific surgeon who was respected by her patients.

“Sometimes they’re afraid to talk to us because they’re afraid that our first recommendation is going to be a surgical one. That’s not always the case; there are lots of things we can do besides operate,” Day says in a promotional video for Spectrum Health that has since been taken down from its website.

In a lawsuit filed in Grand Rapids Federal Court last month, Day claims she discovered problems with Spectrum Medical Health Group’s use of physician assistants and Medicare billings in October 2016. But after reporting the problems, Day said she was diagnosed with breast cancer, which led to a double mastectomy and months of chemotherapy.

Day said she was the target of a “sham peer review” as she was fighting for her life.

During her leave, Day claims some of her fellow doctors – specifically department head Dr. Peter Jebson and Dr. Charles Sherry — started going through her patient files.

It was determined by her peers and the administration that there was not enough proof that more than a dozen surgeries she performed were necessary. Spectrum Health says it repaid several of Day’s patients.

Day was suspended while the internal investigation took place. When she was medically cleared to return to work in April, she was unable to resume her practice.

In the lawsuit, Day says she was unable to defend herself in person, and being suspended during the investigation is not how the medical group has treated other male doctors in similar situations.

Day is asking for her job back, lost wages and an undetermined amount of punitive damages.

Spectrum Health would not comment on the specifics of the lawsuit, but issued the following statement:

“While it is not our practice to comment on pending or active litigation, we deny the allegations of this lawsuit and will vigorously defend against these untrue claims. Spectrum Health does not tolerate or engage in discrimination, harassment or retaliatory behavior and strives to maintain compliance with all federal and state laws, including those pertaining to patient billing. Our Code of Excellence requires our employees to follow good business practices to avoid fraud, waste and abuse and to conduct themselves in accordance with only the highest ethical standards.”

Spectrum has until March 19 to respond to the lawsuit.

24 Hour News 8 spoke to Day’s attorney who declined an on-camera interview for herself or her client.