Noninvasive Breast Cancer

Abstract

Noninvasive breast cancer includes ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS). Phyllodes tumors are rare stromal tumors whose histology and behavior vary from benign to malignant. In both DCIS and LCIS, abnormal cells are present within the lining of the duct or lobule but have not invaded through the basement membrane. These lesions have different behaviors and different demographic profiles. Neither DCIS nor LCIS has potential for metastases. The majority of in situ breast cancers are DCIS. DCIS represents a premalignant marker for invasive breast cancer risk in the ipsilateral breast, whereas LCIS confers an increased risk for the development of invasive breast cancer in both breasts. The majority of DCIS are found radiographically, while the majority of LCIS are found incidentally on biopsy. Immunohistochemical staining with E-cadherin allows differentiation of DCIS and LCIS. Identification of histologic subtypes of DCIS allows for prognostication and aids management decisions. The treatment and prevention goals are more aggressive for DCIS compared to LCIS. When possible, breast conservation with wide excision to negative margins is generally followed by postoperative radiation. Unlike DCIS, clear margins (except for the pleomorphic subtype) are not required for excision of LCIS, and ipsilateral mastectomy and radiation are not indicated. Women with estrogen receptor-positive DCIS benefit from adjuvant endocrine therapy, and trials suggest that women with LCIS may benefit from tamoxifen or raloxifene. Phyllodes tumors are mostly benign lesions with malignant potential. Surgical treatment for the majority of phyllodes tumors is wide local excision. Adjuvant radiotherapy may be beneficial for malignant and borderline phyllodes tumors treated with breast-conserving surgery.