Table of contents
Ductal carcinoma in situ
DCIS of the breast is the proliferation of malignant epithelial cells within the mammary ductal system without involving the basement membrane or invasion into the surrounding stroma.
DCIS is caused mainly by chromosomal imbalances including loss of heterozygosity and overexpression of the HER2/neu proto-oncogene and mutation in the p53 tumor suppressor gene.
DCIS is clinically silent in most cases; however, a breast lump or bloody nipple discharge may be present. Progression may lead to invasive breast cancer.
Prognosis and risk of recurrence
DCIS is not associated with any excess risk of death, except in women aged < 50 years with a standard mortality ratio of 3.44 (95% CI 1.85-6.40).
The following summarized guidelines for the management of ductal carcinoma in situ are prepared by our editorial team based on guidelines from the American Society for Radiation Oncology (ASTRO/ASCO 2016).
Systemic therapy: as per ASCO 2016 guidelines, rates of ipsilateral breast tumor recurrence are reduced with endocrine therapy, but there is no evidence of an association between endocrine therapy and negative margin width.
Whole-breast radiation therapy
As per ASCO 2016 guidelines:
A positive margin, defined as ink on DCIS, is associated with a signicant increase in ipsilateral breast tumor recurrence; the use of whole breast radiotherapy does not nullify this increased risk.
Avoid choosing whole-breast radiotherapy delivery technique, fractionation, and boost dose on the basis of negative margin width.
Surgical excision: as per ASCO 2016 guidelines, higher rates of ipsilateral breast tumor recurrence are reported with treatment with excision alone, regardless of margin width, than treatment with excision and whole breast radiotherapy.