DETROIT, MI -- An oncology expert's review of medical records for 100 former patients of disgraced cancer doctor Farid Fata revealed thousands of unnecessary, physically taxing drug dosages.

Harvard Medical School professor of hematologic oncology David Steensma counted 2,770 medically unnecessary chemotherapy drug dosages prescribed to patients who had, or were misdiagnosed with myelodysplastic syndromes, multiple myeloma and acute myelogenous leukemia.

There were abnormal drug combinations, strange dosage levels, extraordinarily extended chemotherapy periods and outpatient treatments for people who should have been watched closely as inpatients, Steensma said.

"I had difficulty recognizing the regimens that were given," he said in Fata's federal court case Wednesday.

"They were given in combinations that just didn't make much sense... I've never seen anything like this."

Fata pleaded guilty in September 2014 to 13 counts of health care fraud, two money laundering counts and one count of conspiracy to pay or receive kickbacks.

The Michigan doctor and his lawyers concede that there was mistreatment of some form in 553 of his cases.

Steensma also found a total of 3,556 questionable dosages of intense drugs used during chemotherapy to prevent infections and treat nausea, anemia, diarrhea, immunoglobulin deficiency, iron deficiency and iron toxicity.

"If he wasn't giving the chemo, then there would be no need for supportive care," Steensma said in the third day of Fata's sentencing hearing before U.S. District Judge Paul Borman in Detroit.

Former Patient Robert Sobieray is left with one tooth in his mouth after being misdiagnosed with multiple myeloma and treated with chemotherapy under Fata's care.

He spoke in court Tuesday turning to Fata and demanding he look at what's left of his mouth. (Related: Victims face disgraced cancer doctor: 'Farid Fata, I hate you')

"I don't know what I've done to you, what my family has done to you," Sobieray said to Fata before turning to the judge. "I get so upset, your honor, thinking about him... I do hope you give him life, the maximum sentence you can give him by law."

Prosecutors have asked Borman to issue a 175-year federal prison sentence.

Fata's lawyers have asked for 25 years.

While not denying there were many instances of mistreatment, defense lawyers have sought to characterize some of them as mistakes made by a doctor with aggressive cancer-fighting technique.

"People can make mistakes, and there is support in this bone marrow biopsy for treating MDS," said defense attorney Mark Kriger while cross-examining Steensa on a misdiagnosis of myelodysplastic syndrome.

"One doesn't look at a single test in isolation," responded Steensa.

"In your opinion, it was malpractice?" asked Kriger.

"I don't know what the legal definition of malpractice was. It was inappropriate treatment," said Steensa.

The government has also asked Borman to order the doctor to pay back $17.6 million paid by Medicare and Blue Cross/Blue Shield of Michigan for fraudulent treatments. The figure doesn't include patient co-pays or coinsurance contributions, according to court documents.

A decision is likely to come Thursday or Friday.

Fata ran Michigan Hematology Oncology Centers with offices in the Detroit area and Lapeer County until his arrest in August 2013, which came after a series of FBI interviews with employees.

He's been held behind bars since.