ST. CLOUD — An internal investigation has found that some patients at the CentraCare Health Coborn Cancer Center received improper doses of radiation, leading to discipline and firings of some employees.

CentraCare President and CEO Ken Holmen said the errors affected a small group of patients. He wouldn’t give a number but said they’ve all been contacted. He also would not say how many employees have been disciplined or fired.

He said most of the affected patients didn’t get enough radiation, meaning a small increase in the chance of a recurrence of their cancer.

But some received doses that caused serious complications. Seventy-nine-year-old Betty Zollner of Paynesville suffered partial paralysis after the radiation damaged a healthy section of spine near her tumor.