Introduction: Ductal Carcinoma in situ


The term "carcinoma in situ" refers to the proliferation of malignant cells confined to the tissue of origin. Ductal carcinoma in situ (DCIS) consists of malignant epithelial cells confined to the milk ducts of the breast. These cells have the microscopic appearance of cancer cells but have not yet obtained the ability to breach the basement membrane surrounding the duct. There is general consensus that DCIS represents an intermediate step between normal breast tissue and invasive breast cancer. If left untreated, even the lowest grade DCIS lesions have a greater than 30% risk of becoming invasive breast cancer over a lifetime.

Prior to the institution of routine mammography, most lesions were found by palpation or were symptomatic. Today the average DCIS lesion is small (1-1.5 cm) and is rarely detected by manual breast examination. Approximately 80-85% of DCIS is diagnosed by mammography. DCIS often appears on mammography as linear or multiple clusters of fine granular calcifications with a branching-type pattern. Unfortunately mammography cannot differentiate lesions which will soon become invasive. Diagnosis and tumor grading is usually confirmed with a vaccum assisted large bore needle biopsy or surgical excision.

The risk factors for DCIS and invasive breast cancer are similar. The diagnosis of DCIS is rare in women younger than 30 years, it is low in women younger than 40 years but increases steadily from age 40 to 50 years. diagnosis increases much more slowly after age 50 years and plateaus after age 60 years. The prevalence of DCIS is greater in white women than in African American, Asian and women of other ethnicities.

When treated with currently available therapies, DCIS is a associated with high rates of long-term, disease-free survival (96%–98%). In 2005, an estimated one-half million U.S. women were living with a diagnosis of DCIS. Assuming constant incidence and survival rates, it is estimated that by 2020 more than 1 million living U.S. women will have a diagnosis of DCIS.

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