Retired Maj. Gen. Kathryn George Frost, who was the highest ranking woman in the Army when she stepped down last year after a 31-year career, died Friday of breast cancer. She was 57. Frost was commander of the Army and Air Force Exchange Service, or AAFES, which operates the commissaries and post and base exchanges on military installations nationally and overseas, including Afghanistan and Iraq. She worked in Berlin on the staff of then-Gen. Colin Powell when he was chairman of the Joint Chiefs of Staff. She also worked as a White House social aide during the administrations of President Reagan and the first President Bush. Mrs. Frost is noted in the obituary as earning a master's degree in counseling from Wayne State University while on active duty with the Army.