Diagnosis, clinical staging, and treatment of breast cancer: a retrospective multiyear study of a large controlled population.

This study compares diagnosis, staging, and treatment of newly diagnosed breast cancer cases over a several-year period. The study design was a retrospective, multiyear comparison between new breast cancer cases diagnosed in 1995 (n = 827) and 1997 (n = 815). Cases were identified through claims data, and medical record abstraction was used to verify each case and to identify clinical staging and type of treatment.