Biologic variables and prognosis in patients with ductal carcinoma in situof the breast

Ductal carcinoma in situ of the breast is a heterogeneous group of lesions with diverse malignant potential. It is the most rapidly growing subgroup w ithin the breast cancer family with more than 42 000 new cases diagnosed in the USA during 2000. Most new cases are nonpalpable and discovered mammogr aphically. Treatment is controversial and ranges from excision only, to exc ision with radiation therapy, to mastectomy. Prospective randomized trials reveal an approximate 50% reduction in local recurrence rate overall, but t he published prospective data do not allow the selection of subgroups in wh om the benefit from radiation therapy is so small that its risks outweigh i ts benefits. Nonrandomized single-facility series suggest that nuclear grad e, comedonecrosis, tumour size and margin width are all important factors i n predicting local recurrence and that one or more of these factors could b e used to select subgroups of patients who do not benefit sufficiently from radiation therapy to merit its use. When conservative treatment fails., ap proximately 50% of all local recurrences are invasive breast cancer. In spi te of this, the mortality rate following invasive local recurrence is relat ively low, about 12% with 8 years of actuarial follow-up. When all patients with ductal carcinoma in situ are considered, the overall mortality from b reast cancer is extremely low, only about 1-2%. Genetic changes routinely p recede morphologic evidence of malignant transformation. Medicine must lear n how to recognize these genetic changes, exploit them, and in the future, prevent them. (C) 2001 Harcourt Publishers Ltd.