Aged Aged, 80 and over Cause of Death Centralized Hospital Services--organization & administration Colectomy--methods Databases, Factual Disease-Free Survival Elective Surgical Procedures--statistics & numerical data Emergency Treatment--statistics & numerical data Female Hospitals, High-Volume Humans Male Middle Aged New York Prognosis Program Evaluation Quality Improvement Rectal Neoplasms--mortality Rectum--surgery Retrospective Studies Risk Assessment Survival Rate