Vexed surgeons, perplexed patients, and breast cancers which may not be cancer.

In situ cancer of the breast is being diagnosed with increasing frequency due to the widespread use of mammography and heightened awareness of these lesions among pathologists. Treatment of these preinvasive cancers is controversial in light of recent data supporting breast-conserving therapy for small invasive cancers. Therapy for in situ breast cancer is discussed with attention to known risk factors for recurrence and breast cancer-related mortality. The controversies surrounding treatment of ductal and lobular carcinoma in situ compel the conscientious oncologist to seek fully informed consent and to respect the individual patient's feelings about cosmesis and breast cancer risk. Hopefully, prospective randomized studies such as the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-17 trial will relieve the oncology community of much of its confusion about the natural history and optimal therapy for these diseases.