The commissioner may cancel the repayment of a loan received by a person who earns a professional doctor of medicine degree or a doctorate of psychology and who is employed by the Texas Youth Council, the State Department of Public Welfare, the Texas Department of Corrections, or the Department of Mental Health and Mental Retardation. Such cancellation shall be in compliance with a contract to be entered between the commissioner and the eligible person as provided in the Texas Education Code, §52.40.